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A semi-trailer is a trailer without a front axle. A large proportion of its weight is supported by a road tractor, a detachable front axle assembly known as a dolly, or the tail of another trailer. A semi-trailer is normally equipped with landing gear (legs which can be lowered) to support it when it is uncoupled. A road tractor coupled to a semi-trailer is often called a semi-trailer truck or semi in the US and an articulated lorry or artic in the UK. The fifth wheel on a truck connects to a semi trailer Kingpin. Kingpins come in many guises, however the most common within the UK market is the 2.0" (50.8mm) EEC approved type. This Kingpin is fully interchangeable and, given a strict maintenance schedule, it should last the life of a trailer. In Australian English, the tractor unit is usually referred to as a prime-mover; and the combination of a prime-mover and trailer is known as a semi-trailer or semi. Semi-trailers with two trailer units are called B-Doubles (or in American English often just doubles), and in some cases (especially when there are three or more trailers), road trains. A B-double consists of a prime mover towing two semi-trailers, where the first semi-trailer is connected to the prime mover by a fifth wheel coupling and the second semi-trailer is connected to the first semi-trailer by a fifth wheel coupling. A road train means a combination, other than a B-Double, consisting of a motor vehicle towing at least two trailers (counting as a single trailer a converter dolly supporting a semi-trailer).][ In road haulage, semi-trailers predominate over full-trailers because of their flexibility. There are two types of couplings: fifth wheel coupling and automatic. In some applications, no separable coupling is fitted, and the trailer is bolted to the tractor unit, using a bearing and rocker feet as are used under a fifth wheel skid plate. The towing vehicle has a wide coupling plate known as a fifth wheel coupling bolted onto its chassis on which the semi-trailer rests and pivots. As the tractor reverses under the trailer, a king-pin under the front of the trailer slides into a slot in the skidplate, and the jaws of the fifth wheel close on to it. The driver has to raise the trailer legs manually, and couple the airbrake lines and electrical cables. Many years ago, automatic couplings predominated][ but are now quite rare. Automatic couplings were generally used for payloads of 12 tons][ or less, e.g. on the Scammell Mechanical Horse. There is no coupling plate on the tractor. There is a turntable permanently fixed to the underside of the trailer. This locks to the chassis of the tractor. When the tractor reverses under the trailer, its legs rise and the brake and electrical connections are made automatically. Almost the entire coupling and uncoupling procedure is operated by the driver from inside the cab, except that he or she has to descend to release (or apply) the trailer parking brake.][ Different types of semi-trailers are designed to haul different cargoes. Common widths are 8 feet (2.44 m), and 2.6 metres (8 ft 6.4 in).
A semi-trailer truck is a large vehicle that consists of a towing engine, known as a tractor in the United States and truck in many other places, attached to one or more semi-trailers to carry freight. It is also known as a transport in Canada; prime mover in Australia; semi, tractor-trailer, big rig, or 18-wheeler in the United States; and articulated lorry, abbreviated artic, in Britain and Ireland. A semi-trailer does not trail completely behind the towing vehicle, but is attached at a point that is just forward of the rear-most axle of the towing unit. This is done so that a large portion of the weight of the trailer is carried by the prime mover. This arrangement means that both tractor and semi-trailer will have a distinctly different design than a rigid truck and trailer. In North America, the combination vehicles made up of a powered truck and one or more detachable trailers, are known as "semi-tractor-trailers", "tractor-trailers", "semis", "big rigs" or "eighteen-wheelers". The "tractors", or powered trucks, have two or three axles; those built for hauling heavy-duty commercial-construction machinery may have as many as four or five axles, some often being lift axles. The most common tractor-cab layout has a forward engine, one steering axle, and two drive axles. The "fifth-wheel" trailer coupling on most tractor trucks is movable fore and aft, to allow adjustment in the weight distribution over its rear axle(s). Ubiquitous in Europe, but less common in the USA since the 1990s, is the cabover configuration, where the driver sits next to, or over the engine. With changes in the US to the maximum length of the combined vehicle, the cabover was mostly phased out of North-American "over-the-road" or "long-haul" service by 2007. Cabovers were notorious for being difficult to service, as the cab could not be lifted on its hinges to a full 90-degree forward tilt, and this severely limited access to the front part of the engine. Trucks average between 4 and 8 miles per gallon, with fuel economy standards requiring more than 7 miles per gallon efficiency by 2014. The cargo trailer usually has a "tandem" axle pair at the rear, each of which has dual wheels, or eight wheels on the trailer, four per axle. Many trailers are equipped with a movable tandem to allow adjusting the weight distribution. The combination of eight tires on the trailer and ten tires on the tractor is what led to the moniker "eighteen wheeler". The United States also allows two-axle tractors to pull two single-axle 28.5 ft (8.7 m) semi-trailers, known officially as STAA doubles, and colloquially as doubles, a set, or a set of joints, on all highways that are part of the national network. To connect the second of a set of doubles to the first trailer, and to support the front half of the second trailer, a converter gear, also known as a con-gear or dolly is used. This apparatus has one or two axles, a fifth-wheel coupling for the rear trailer, and a tongue with a ring-hitch coupling for the forward trailer. Individual states may further allow longer vehicles, known as "longer combination vehicles" or LCVs), and may allow them to operate on roads other than those that are part of the national network. LCV types include: Regulations on LCVs vary widely from one state or province to another. None allows more than three trailers without a special permit. Reasons for limiting the legal trailer configurations include both safety concerns and the impracticality of designing and constructing roads that can accommodate the larger wheelbase of these vehicles and the larger minimum turning radii associated with them. Most states restrict operation of larger tandem trailer setups such as triple units, "turnpike doubles" and "Rocky-Mountain doubles". In general, these configurations are restricted to turnpikes. Except for these units, tandem setups are not restricted to certain roads any more than a single setup. They are also not restricted by weather conditions or "difficulty of operation". The Canadian province of Ontario, however, does have weather-related operating restrictions for larger tandem trailer setups. In the United States, 80,000 pounds (36,287 kg) is the maximum allowable legal gross vehicle weight without a permit. The axle-weight breakdown is:
Over-length and overweight permits are issued by each individual state whose roads will be traveled. The permits are usually issued in advance, for a specific period of time, over a specific route, with a specific load. Most over-length loads require escorts. An escort is an accompanying automobile and its driver, who communicates with the driver of the payload vehicle regarding the position of the load in relation to the road and shoulder, and about other situational considerations. A trailer's dimensions can vary greatly, depending on the amount and type of cargo it is designed to haul. In the United States, they are normally limited to 8.5 feet (2.6 m) in width. (See types of trailers under Construction, below.) Although dual wheels are the most common, use of two single, wider tires, known as "super singles", on each axle is becoming popular among bulk cargo carriers and other weight-sensitive operators. With increased efforts to reduce greenhouse gas emissions, the use of the super-single tire is gaining popularity. There are several advantages to this configuration. The first of these is that super singles reduce fuel consumption. In 1999, tests on an oval track showed a 10% fuel savings when super singles were used. These savings are realized because less energy is wasted flexing fewer tire sidewalls. Second, the lighter overall tire weight allows a truck to be loaded with more freight. The third advantage is that the single wheel covers less of the brake unit, which allows faster cooling and reduces brake fade. One of the major disadvantages of the super singles is that they are currently not as widely available as a standard tire. In addition, if a tire should become deflated or be destroyed, there isn't another tire attached to the same hub to maintain the dynamic stability of the vehicle, as would be the case with dual wheels. With dual wheels, the remaining tire may be overloaded, but it will typically allow the vehicle to be safely stopped or driven to a repair facility. Another innovation rapidly growing in popularity is the skirted trailer. The area between the road and the bottom of the trailer frame was left open until it was discovered that the air moving under the trailer is a source of aerodynamic drag. Three Split Skirt (SS) concepts were EPA-verified to provide fuel savings greater than 5%, and four Split Skirts concepts had EPA-verified fuel savings between 4 and 5%. The drawback to skirts is that they make the trailers more vulnerable to high crosswind loading and therefore more susceptible to "dog-legging," which is the misalignment of truck and trailer, or rolling over in a crosswind situation. Another drawback is that skirted trailers require more steps to remove wheels after a blowout. The noticeable difference between tractor units in the North American and Europe is that almost all European models are "cab over engine" (COE or forward control), while the majority of North American trucks are conventional (or normal control). For repairs, the entire cab hinges forward to allow maintenance access. European trucks, whether small rigid or fully articulated, have a sheer face on the front. This allows for shorter trucks with longer trailers (with larger freight capacity) within the legal maximum total length. Furthermore, it offers greater manoeuvrability and better overview for the driver. Conversely, "conventional" cab tractors offer the driver a more comfortable driving environment and better protection in a collision as well as eliminating the need to empty the driver's personal effects from the tractor whenever the engine requires service. In Europe usually only the rear tractor axle has twin wheels, while larger size single wheels are used for the cargo trailer. The most common combination used in Europe is a semi tractor with two axles and a cargo trailer with three axles, giving five axles and 12 wheels in total. Lesser used (common in Scandinavia) are tractors with three axles, which feature twin wheels either on one or both rear axles. In addition to the most common three axles variant, cargo trailers with only two or only one axle are in use, again usually with larger single wheels. In Finland (and Sweden) lumber trucks and long distance freight is run on 7 or 8 axle combinations up to 60,000 kg in weight and 25,25 metres long. Semi-trailers are used for short distance freight. In the UK the maximum permitted gross weight of a semi-trailer truck, without the use of a Special Type General Order (STGO), is 44,000 kg (97,000 lb), which is the heaviest permitted legal weight for a single semi-trailer truck in the world. In order for a 44 tonne semi-trailer truck to be permitted on UK roads the tractor and semi-trailer must have 3 or more axles each. Lower weight semi-trailer trucks can mean some tractors and trailer having fewer axles. In practice, like double decker buses and coaches in the UK, there is no legal height limit for semi-trailer trucks; however, bridges over 16.5 ft (5.03 m) do not have the height marked on them. Semi-trailer trucks on Continental Europe have a height limit of 4.0 metres. Vehicles heavier than 44,000 kg (97,000 lb) are permitted on UK roads but are indivisible loads, which would be classed as abnormal (or oversize). Such vehicles are required to display an STGO (Special Types General Order) plate on the front of the tractor unit and, under certain circumstances, are required to travel by an authorised route and have an escort. Most UK trailers are 45 feet (13.7 metres) long and, dependent on the position of the fifth wheel and kingpin, a coupled tractor unit and trailer will have a combined length of between 50 and 55 feet (15.25 and 16.75 metres). Although the Construction and Use Regulations allow a maximum rigid length of 60 feet (18.2 metres), this, combined with a shallow kingpin and fifth wheel set close to the rear of the tractor unit, can give an overall length of around 75 feet (22.75 metres), although combinations of this length are usually used only to carry steel or concrete beams. Providing certain requirements are fulfilled, a Special Types General Order (STGO) allows for vehicles of any size or weight to travel on UK roads. However, in practice any such vehicle has to travel by a route authorised by the Department of Transport and move under escort. The escort of abnormal loads in the UK is now predominantly carried out by private companies, but extremely large or heavy loads that require road closures must still be escorted by the police. In the UK, some articulated trucks have 8 tyres on 3 axles on the tractor; these are known as 6-wheelers or "6 leggers", with either the centre or rear axle having single wheels which normally steer as well as the front axle and can be raised when not needed (i.e. when unloaded or only a light load is being carried; an arrangement known as a TAG axle when it is the rear axel, or mid-lift when it is the centre axel). Some trailers have 2 axles which have twin wheels on each axle; other trailers have 3 axles, of which 1 axle can be a lift axle which has super-single wheels. In the UK, two wheels bolted to the same hub are classed as a single wheel, therefore a standard six-axle articulated truck is considered to have twelve wheels, even though it has twenty tyres. The UK also allows articulated truck tractors which have 6 tyres on 2 axles; these are known as 4-wheelers. In 2009 the operator Denby Transport designed and built a 25.25 metre long B-Train (or B-Double) semi-trailer truck called the Denby Eco-Link to show the benefits of such a vehicle, which were a reduction in road accidents and result in less road deaths, a reduction in emissions due to the one tractor unit still being used and no further highway investment being required. Furthermore Denby Transport asserted that two Eco-Links would replace three standard articulated lorries while if limited to the current UK weight limit of 44 tonnes, it was claimed the Eco-Link would reduce carbon emissions by 16 per cent, and could still halve the number of trips needed for the same amount of cargo carried in conventional lorries. This is based on the fact that for light but bulky goods such as toilet paper, plastic bottles, cereals and aluminium cans, conventional lorries run out of cargo space before they reach the weight limit.[2][4] At 44 tonnes, as opposed to 60 tonnes usually associated with B-Trains, the Eco-Link also exerts less weight per axle on the road compared to the standard 6 axle 44 tonne articulated combination. The vehicle was built after Denby Transport believed they had found a legal-loophole in the present UK law to allow the Eco-Link to be used on the public roads. The relevant legislation concerned the 1986 Road Vehicles Construction and Use Regulations. The 1986 regulations state that "certain vehicles" may be permitted to draw more than one trailer and can be up to 25.9 m (85 ft) in length.[2] The point of law reportedly hinged on the definition of a "towing implement", with Denby prepared to argue that the second trailer on the Eco-Link was one. The Department for Transport were of the opinion that this refers to recovering a vehicle after an accident or breakdown, but the regulation does not explicitly state this. During BTAC performance testing the Eco-Link was given an "excellent" rating for its performance in manoeuvrability, productivity, safety and emissions tests, superseding ordinary lorries in many respects.[23] Private trials had also reportedly shown the Denby vehicle had a 20 per cent shorter stopping distance than conventional lorries of the same weight, due to having extra axles. The active steer system meant that the Eco-Link had a turning circle of just 41 feet, the same as a conventional articulated lorry. Although the DfT advised that the Eco-Link was not permissible on public roads, Denby Transport gave the Police prior warning of the timing and route of the test drive on the public highway, as well as outlining their position in writing to the Eastern Traffic Area Office. On 1 December 2009 Denby Transport were preparing to drive the Eco-Link on public roads, but this was cut short because the Police pulled the lorry over as it left the gates in order to test it for its legality "to investigate any... offences which may be found". The Police said the vehicle was unlawful due to its length and Denby Transport was served with a notice by the Vehicle and Operator Services Agency (VOSA) inspector to remove the vehicle from the road for inspection. Having returned to the yard, Denby Transport was formally notified by Police and VOSA that the lorry could not be used while the Eco-Link, or any other B-Train, have since not been permnitted on UK roads. However, this prompted the The Department for Transport to undertake a desk study in to semi-trailer trucks, which has resulted in the longer semi-trailer trial which commenced in 2012. Starting in January 2012 the Department for Transport is conducting a trial of longer semi-trailers. The trial involves 900 semi-trailers of 14.6m in length (i.e. 1 metre longer than the current maximum), and a further 900 semi-trailers of 15.65m in length (i.e. 2.05 metres longer). This will result in the total maximum length of the semi-trailer truck being 17.5 metres (for trailers of 14.6 metre in length) and 18.55 metres (for trailers of 15.65 metres in length). The increase in length will not result in the 44,000 kg (97,000 lb) weight limit being exceeded and will allow some operators to approach the weight limit which may not have been previously possible due to the previous length of trailers. The trial will run for a maximum of 10 years. The maximum overall length applying in the EU and EEA member states is 18.75 metres with a maximum weight of 40 tonnes, or 44 tonnes if carrying an ISO container. However, rules limiting the semi-trailers to 16.5 metres and 18.75 are met with trucks carrying a standardized 7.82 metre body with one additional 7.82 metre body on tow as a trailer. Since 1996, when Sweden and Finland formally won a final exemption from the European Economic Area rules with 60- tonne and 25.25- metre combinations, all other member states gained the ability to adopt the same rules. In Italy the maximum permitted weight (unless exceptional transport is authorized) is 44000 kg for any kind of combination with 5 axel or more. The 25.25 metres truck combinations were developed under the branding of EcoCombi which influenced the name of EuroCombi for an ongoing standardization effort where such truck combinations shall be legal to operate in all jurisdictions of the European Economic Area. With the 50% increase in cargo weight, the fuel efficiency increases with an average of 20% with a corresponding relative decrease in carbon emissions and with the added benefit of one third fewer trucks on the road. The 1996 EU regulation defines a Europe Module System (EMS) as it was implemented in Sweden. The wording of EMS combinations and EuroCombi are now used interchangeably to point to truck combinations as specified in the EU document; however apart from Sweden and Finland the EuroCombi is only allowed to operate on specific tracks in other EU member states. From 2006, 25.25 m truck trailer combinations are to be allowed on restricted routes within Germany, following a similar (on-going) trial in The Netherlands. Similarly, Denmark have allowed 25.25 metre combinations on select routes. Like in Sweden and Finland, these vehicles in continental Europe will run a 60 ton weight limit. Two types are to be used: 1) a 26 ton truck pulling a dolly and semi-trailer, or 2) an articulated tractor unit pulling a b-double. The UK government has so far decided not to have its own trial of these 60 ton vehicles, but to keep an eye on the other countries' trials. When using a dolly, which generally has to be equipped with lights and a license plate, rigid trucks can be used to pull semitrailers. The dolly is equipped with a fifth wheel to which the trailer is coupled. Because the dolly attaches to a pintle hitch on the truck, maneuvering a trailer hooked to a dolly is different from maneuvering a fifth wheel trailer. Backing the vehicle requires same technique as backing an ordinary truck/full trailer combination, though the dolly/semi setup is probably longer, thus requiring more space for maneuvering. The tractor-semitrailer configuration is rarely used on timber trucks, since these will use the two big advantages of having the weight of the load on the drive wheels, and the loader crane used to lift the logs from the ground can be mounted on the rear of the truck behind the load, allowing a short (lightweight) crane to reach both ends of the vehicle without uncoupling. Also construction trucks are more often seen in a rigid + midaxle trailer configuration instead of the tractor + semitrailer setup. Denmark, the Netherlands and Norway all allow 25.25 m trucks (the Netherlands from 2000, Denmark from 2008, and Norway from 2008 on selected routes). In Sweden the allowed length is 24 metres (78.7 ft) since 1967. Before that, the maximum length was unlimited - the only limitations were on axle load. What stopped Sweden from adopting the same rules as the rest of Europe, when securing road safety was the national importance of a competitive forestry industry. Finland with the same road safety issues and equally important forestry industry followed suit. The change made trucks able to carry three stacks of cut-to-length logs instead of two, as it would be in a short combination. They have one on stack together with a crane on the 6x4 truck, and two additional stacks on a four axle trailer. The allowed gross weight in both countries is up to 60 tonnes (130,000 lb) depending on the distance between the first and last axle. In the negotiations starting in the late 80s preceding the two countries' entries to the European Economic Area and later the European Union, they insisted on exemptions from the EU rules citing environmental concerns and the transportation needs of the logging industry. In 1995, after Sweden and Finland's entry to the union, the rules changed again, this time to allow trucks carrying a standard CEN unit of 7.82 metres to draw a 13.6 metres standard semi-trailer on a dolly, a total overall length of 25.25 metres (82.8 ft). Later B-double combinations came into use, often with one 20 ft container on the b-link and a 40 ft container (or two 20 ft containers) on a semi-trailer bed. In allowing the longer truck combinations, what would take two 16.5 metre semi-trailer trucks and one 18.75 metre truck and trailer to haul on the continent now could be handled by just two 25.25 metre trucks - greatly reducing overall costs and emissions. Prepared since late 2012 and effective on January 2013, Finland has changed its regulations to allow total maximum legal weight of a combination to be 76 tonnes (170,000 lb). At the same time the maximum allowed height would be increased by 20 cm; from current maximum of 4.2 metres to 4.4 metres. The effect this major maximum weight increase would cause to the roads and bridges in Finland on the long run, is heated debate. However, longer and heavier combinations are regularly seen on public roads - special permits are issued for special cargo - not a too uncommon occurrence. Others are: The mining company Boliden AB have a standing special permit for 80 ton combinations on select routes between mines in the inland and the processing plant in Boliden, taking a load of 50 ton ore. Volvo has a special permit for a 32 metres (105 ft), steering B-trailer-trailer combination carrying two 40 ft containers to and from Gothenburgs harbour and Volvo Trucks factory, all on the island of Hisingen. Another example is the ongoing project En Trave Till (lit. One more pile/stack) started in December 2008. It will allow even longer vehicles to further rationalize the logging transports. As the name of the project points out, it will be able to carry four stacks of timber, instead of the usual three. The test is limited to Norrbotten county and the European route E4 between the timber terminal in Överkalix and the sawmill in Munksund (outside Piteå). The vehicle is a 30 metre long truck trailer combination with a gross weight exceeding 90 tonnes (200,000 lb). It is estimated that this will give a 20% lower cost and 20-25% CO2 emissions reduction compared to if the timber instead would have been transported with regular 60 ton truck combinations. As the combinations spreads its weight over more axles, braking distance, road wear and traffic safety is believed to be either the same or improved with the 90 ton truck-trailer. In the same program two types of 74 tonnes (160,000 lb) combinations will be tested in Dalsland and Bohuslän counties in western Sweden. An enhanced truck and trailer combination for use in the forest and a b-double for plain highway transportation to the mill in Skoghall. The Northland Mining has in 2012 got permission for 90 ton combinations with normal axle load (an extra dolly) 150 km Kaunisvaara-Svappavaara, carrying iron ore. Australian road transport has a reputation for using very large trucks and road trains. This is reflected in the most popular configurations of trucks generally having dual drive axles and three axles on the trailers, with 4 tires on each axle. This means that Australian single semi-trailer trucks will usually have 22 wheels which is generally more than their counterparts in other countries. Long haul transport usually operates as B-doubles with two trailers (each with three axles), for a total of nine axles (including steering). In some lighter duty applications only one of the rear axles of the truck is driven, and the trailer may have only two axles. From July 2007 the Australian Federal and State Governments allowed the introduction of B-triple trucks on a specified network of roads. B-Triples are set up differently to conventional road trains. The front of their first trailer is supported by the turntable on the prime mover. The second and third trailers are supported by turntables on the trailers in front of them. As a result, B-Triples are much more stable than road trains and handle exceptionally well. True road trains only operate in remote areas, regulated by each state or territory government. In total, the maximum length that any articulated vehicle may be (without a special permit and escort) is 53.5 metres (175.5 ft), its maximum load may be up to 164 tons (361,558 lb) gross and may have up to 4 trailers. However, heavy restrictions apply to the areas where such a vehicle may travel in most states. In remote areas such as the Northern Territory great care must be taken when sharing the road with longer articulated vehicles that often travel during the day time, especially 4 trailer road trains. Articulated trucks towing a single trailer or two trailers (commonly known as "short doubles") with maximum overall length of 19 metres (62 ft) are referred to as "General access heavy vehicles" and are permitted in all areas, including metropolitan. B-doubles are limited to a maximum total weight of 62.5 ton (137,788 lb) and overall length of 25 metres (82 ft) or 26 metres (85 ft) if they are fitted with approved FUPS (Front Underrun Protection System) devices. B-doubles may only operate on designated roads, which includes most highways and some major metropolitan roads. B-doubles are very common in all parts of Australia including state capitals and on major routes they outnumber single trailer configurations. Maximum width of any vehicle is 2.5 metres (8 ft 2 in) and height of 4.3 metres (14 ft 1 in). In the past few years, allowance has been made by several states to allow certain designs of heavy vehicles up to 4.6 metres (15 ft 1 in) high but they are also restricted to designated routes. In effect, a 4.6 metres high B-double will have to follow two sets of rules: they may access only those roads that are permitted for B-doubles AND for 4.6 metres high vehicles. In Australia, both conventional tractor units and cabovers are common, however cabovers are most often seen on B-Doubles on the eastern seaboard where the reduction in total length allows the vehicle to pull longer trailers and thus more cargo than it would otherwise. Super single tires are sometimes used on tri-axle trailers. The suspension is designed with travel limiting, which will hold the rim off the road for one blown or deflated tire for each side of the trailer, so a trailer can be driven at reduced speed to a safe place for repair. Super singles are also often used on the steer axle in Australia to allow greater loading over the steer axle. The increase in loading of steer tires requires a permit. An Australian prime mover Kenworth and B double trailer combination A road train in Australia B-double truck on the Sturt Highway These are for tractor units, not straight, rigid, box or other heavy vehicles. There are many types of semi-trailers in use, designed to haul a wide range of products. See semi-trailer for more detail. The cargo trailer is, by means of a king pin, hooked to a horseshoe-shaped quick-release coupling device called a fifth wheel or a turntable hitch at the rear of the towing engine that allows easy hook up and release. The truck trailer cannot move by itself because it only has wheels at the rear end: it requires a forward axle, provided by the towing engine, to carry half the load weight. The vehicle has a tendency to fold at the pivot point between the towing vehicle and the trailer when braking hard at high speeds. Such a truck accident is called a 'trailer swing', although it is commonly described as a 'jackknife'. 'Jackknifing' is a condition where the tractive unit swings round against the trailer: not vice-versa. See: jackknifing. Semi trucks use air pressure, rather than hydraulic fluid, to actuate the brakes mainly due to the much larger braking forces required. This also allows for ease of coupling and uncoupling of trailers from the tractor unit, as well as reducing the potential for problems common to hydraulic systems, such as leakage or brake failure caused when overheated brake fluid vaporizes in the hydraulic lines. The most common failure is "brake fade," usually caused when the drums or discs and the linings of the brakes overheat from excessive use. The parking brake of the tractor unit and the emergency brakes of the trailer are spring brakes that require air pressure in order to be released. They are applied when air pressure is released from the system, and disengaged when air pressure is supplied. This is an emergency feature which ensures that if air pressure to either unit is lost, the trailer will stop to a grinding halt instead of not stopping and becoming uncontrollable. The trailer controls are coupled to the tractor through two "gladhand connectors", which provide air pressure, and an electrical cable, which provides power to the lights and any specialized features of the trailer. "Glad-hand" connectors (also known as "palm couplings,") are air hose connectors, each of which has a flat engaging face and retaining tabs. The faces are placed together, and the units are rotated so that the tabs engage each other to hold the connectors together. This arrangement provides a secure connection, but allows the couplers to break away without damaging the equipment if they are pulled, as may happen when the tractor and trailer are separated without first uncoupling the air lines. These connectors are similar in design to the ones used for a similar purpose between railroad cars. Two air lines control the trailer unit. An emergency or main air supply line pressurizes the trailer's air tank and disengages the emergency brake, and a second service line controls the brake application. In the UK male/female quick release connectors "red line" or emergency, have a female on the truck and male on the trailer and a "yellow line" or service has a male on the truck and female on the trailer. This avoids coupling errors (causing no brakes) plus the connections will not come apart if pulled by accident. The three electrical lines will fit one way round a primary black a secondary green and an ABS lead, all of these lines are collectively known as "suzies" or "suzie coils". Another braking feature of semi-trucks is the engine braking, which could be either compression brake (usually shortened to "Jake brake") or exhaust brake or combination of both. The use of compression brake alone however produces a loud and distinctive noise, and owing to noise pollution, some local municipalities have prohibited or restricted the use of engine brake systems inside their jurisdictions, particularly in residential areas. The advantage to using this instead of conventional brakes is that a truck can travel down a long grade without overheating its wheel brakes. Some vehicles can also be equipped with hydraulic or electric retarders which have an advantage of near silent operation. Because of the wide variety of loads the "semi" may carry, they usually have a manual transmission to allow the driver to have as much control as possible. However, all truck manufacturers now offer semi-automatic transmissions (manual gearboxes with automated gear change), as well as automatic transmissions. "Semi" truck transmissions can have as few as 9 forward speeds or as many as 18 forward speeds (plus 2 reverse speeds). A large number of transmission ratios means the driver can operate the engine more efficiently. Modern on-highway diesel engines are designed to provide maximum torque in a narrow RPM range (usually 1200-1500 RPM); having more gear ratios means the driver can hold the engine in its optimum range regardless of road speed (drive axle ratio is also a critical factor). A ten speed manual transmission, for example is controlled via a six-slot H-box pattern, similar to that in five-speed cars — five forward and one reverse gear. Gears six to ten (and high speed reverse) are accessed by a Lo/High range splitter; gears 1-5 are Lo range; gears 6-10 are High range using the same shift pattern. A Super-10 transmission, by contrast, has no range splitter; it uses alternating "stick and button" shifting (stick shifts 1-3-5-7-9, button shifts 2-4-6-8-10). 13,15 and 18 speed transmission have the same basic shift pattern, but include a splitter button to access to additional ratios found in each range. Some may have 12. Another difference between semi-trucks and cars is the way the clutch is set up. On an automobile, the clutch pedal is depressed full stroke to the floor for every gear shift to ensure the gearbox is disengaged from the engine. On a semi-truck with constant mesh transmission (non synchronized), such as by the Eaton Roadranger series, not only is double clutching required, but a clutch brake is required as well. The clutch brake stops the rotation of the gears, and allows the truck to be put into gear without grinding when stationary. The clutch is pressed to the floor only to allow smooth engagement of low gears when starting from a full stop; when moving, the clutch pedal is pressed only far enough to break torque for gear changes. An electrical connection is made between the tractor and the trailer through a cable often referred to as a "pigtail." This cable is a bundle of wires in a single casing. Each wire controls one of the electrical circuits on the trailer, such as running lights, brake lights, turn signals, etc. A standard cable would break when the rig went around corners so it is coiled and retains these coils when not under tension. It is these coils that cause the cable to look like a pigtail. In most countries a trailer or semi-trailer must have minimum This is an assembly hanging down from the bottom of the rear of the trailer. It is intended to provide some protection for cars which start to run into the rear of the trailer. This came into use in the aftermath of the accident that killed Jayne Mansfield on June 29, 1967; the car she was in hit the rear of a tractor-trailer. The bottom of the rear of the trailer is near head level for an adult in a car, and without the underride guard, the only protection for such an adult's head in such an accident would be the car's windshield. A special driver's license is required to operate various commercial vehicles. Regulations vary by province. A license to operate a vehicle with air brakes is required (i.e., normally a Class I, II, or III commercial license with an "A" or "S" endorsement in provinces other than Ontario). In Ontario, a "Z" endorsement is required to drive any vehicle using air brakes; in provinces other than Ontario, the "A" endorsement is for air brake operation only, and an "S" endorsement is for both operation and adjustment of air brakes. Anyone holding a valid Ontario driver's license (i.e., excluding a motorcycle license) with a "Z" endorsement can legally drive any air-brake-equipped truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicle) up to 11 metric tonnes, that includes one trailer weighing no more than 4.6 tonnes if the license falls under the following three classes: Class E (school bus—maximum 24-passenger capacity or ambulance), F (regular bus—maximum 24-passenger capacity or ambulance) or G (car, van, or small-truck). A Class B (any school bus), C (any urban-transit-vehicle or highway-coach), or D (heavy trucks other than tractor-trailers) license enables its holder to drive any truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicle) greater than 11 tonnes, that includes one trailer weighing no more than 4.6 tonnes. Anyone holding an Ontario Class A license (or its equivalent) can drive any truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicles) greater than 11 tonnes, that includes one or more trailers weighing more than 4.6 metric tonnes. Drivers of semi-trailer trucks generally require a Class A commercial driver's license to operate any combination vehicles with a combined Gross Vehicle Weight Rating (or CGVWR) in excess of 26,000 pounds (11.8 t) if the gross vehicle weight rating (GVWR) of the towed vehicle(s) is in excess of 10,000 lbs. Some states (such as North Dakota) provide exemptions for farmers, allowing non-commercial license holders to operate semis within a certain air-mile radius of their reporting location. State exemptions, however, are only applicable in intrastate commerce, only the stipulations of the Code of Federal Regulations (CFR) may be applied in interstate commerce. Also a person under the age of 21 cannot operate a commercial vehicle outside the state where the commercial license was issued. This restriction may also be mirrored by certain states in their intrastate regulations. A person must be at least 18 in order to be issued a commercial license. In addition, Endorsements are necessary for certain cargo and vehicle arrangements and types; The Road Traffic Security Rules (zh:道路交通安全規則) require a combination vehicle driver license (Chinese: ) to drive a combination vehicle (Chinese: ). These rules define a combination vehicle as a motor vehicle towing a heavy trailer, i.e., a trailer with a gross weight of more than 750 kilograms (1,653 lb). A category CE driving licence is required to drive a Tractor-trailer. Truck drivers in Australia require an endorsed license. These endorsements are gained through training and experience. The minimum age to hold an endorsed license is 18 years, and/or must have held open (full) driver's license for minimum 12 months. The following are the heavy vehicle license classes in Australia: In order to obtain a HC License the driver must have held an MR or HR license for at least 12 months. To upgrade to an MC License the driver must have held a HR or HC license for at least 12 months. From licenses MR and upward there is also a "B" Condition which may apply to your license if you do your testing in a Synchromesh or Automatic Transmission Vehicle. To remove the "B"Condition you must prove to the Motor Registry (In any jurisdiction) that you have the ability to drive a constant mesh Transmission using the clutch. Constant Mesh transmission refers to "Crash Box" transmissions, predominantly Road Ranger 18 Speed Transmission in Australia. In New Zealand drivers of heavy vehicles require specific licences, termed as 'classes'. A Class 1 Drivers Licence (aka a Car License) will allow the driving of any vehicle with Gross Laden Weight (GLW) or Gross Combination Weight (GCW) of 4500 kg or less. For other types of vehicles the Classes are separately licensed as follows: Further information on the New Zealand Licensing system for Heavy Vehicles can be found at Land Transport New Zealand. Modern day semi-trailer trucks often operate as a part of a domestic or international transport infrastructure to support containerized cargo shipment. Various types of rail flat bed train cars are modified to hold the cargo trailer or container with wheels or without. This is called "Intermodal" or "piggy-back" or "piggyback". The system allows the cargo to switch from the highway to railway or vice versa with relative ease by using gantry cranes. The large trailers pulled by a tractor unit come in many styles, lengths, and shapes. Some common types are: vans, reefers, flatbeds, sidelifts and tankers. These trailers may be refrigerated, heated, ventilated, or pressurized, depending on climate and cargo. Some trailers have movable wheel axles that can be adjusted by moving them on a track underneath the trailer body and securing them in place with large pins. The purpose of this is to help adjust weight distribution over the various axles, to comply with local laws. "Roll On" by Alabama and "Papa loved momma" Garth Brooks
A tractor unit, semi tractor(U.S.) , prime mover (Australian English), road tractor, or traction unit is a heavy-duty commercial vehicle within the large goods vehicle category, usually with a large displacement diesel engine, and several axles. The tractor unit serves as a method of moving trailers (most often semi-trailers). Different trailers can be swapped between tractor units quickly, so the tractor unit does not stand idle whilst the load is unloaded or loaded, unlike a rigid, and is not restricted to one type of goods as trailer types can be swapped e.g. bulk tipper to a box van. The tractor-trailer combination also means a load can be shared across many axles, yet be more maneuverable than an equivalently sized rigid truck (see trucks). The tractor unit couples to the trailer using some sort of mechanical lock system, usually a fifth wheel coupling. A tractor unit is primarily designated a freight vehicle, and is most common in the heavy goods vehicle (HGV) class of vehicles, although smaller, van-based tractor units do exist. There have been three common cab configurations used in tractors, two are still widely used. The conventional has an engine and hood over the front axle in front of the cab, as in most automobiles. This style is almost universal in the U.S. The cab over engine has a flat nose cab with the driver sitting in front of the front axle. Widely used in the EU, this style has the advantages of good vision, maneuverability, and allows maximum trailer length relative to overall length. In the U.S. this type of cab can be useful in strait trucks, but now has little advantage in tractors and is rarely used. A U.S. style cab over engine, now largely obsolete, had a flat nose cab located higher over the engine, with the driver sitting above the front axle. This allowed a sleeper compartment in a short tractor, and maximum wheelbase relative overall length, important for bridge formula weight restrictions. With the loosening of length restrictions in 1982 this style had limited applications, and is no longer manufactured in the U.S. A tractor unit can have many axles depending on axle load legislation. The most common varieties are those of 4x2, 6x2 and 6x4 types. However, some manufacturers offer 6x6, 8x6, 8x8, 10x8, and 10x10 axle configurations. A 6x4 has three axles, with two of the axles driven. 6x4 units are more common in long distance haulage in larger countries such as the USA and Australia. In Europe, the 4x2 and 6x2 variants are more commonplace. Those with three axles or more can have more than one steering axle, which can also be driven. Most 6x2 units allow the undriven rear axle to be raised when lightly loaded, or running without a trailer, to save tyre wear, and increase traction. The 6x6 units have three axles, all driven, and 8x6 units have four axles, with the rear three usually driven and the front axle for steering. The 8x8 units also have four axles, but with all of them driven, and 10x8 units have five axles with the rear four usually driven and the front axle for steering. All five axles of 10x10 units are driven. The front two axles are usually both steer axles. The axle configurations are usually based on axle load legislation, and maximum gross vehicle weight ratings (BDM). Heavier versions of tractor units, such as those used in heavy haulage and road trains, tend to have four or more axles, with more than two axles driven. In certain countries (such as Switzerland), a certain amount of weight must be spread over driven axles, which lead to heavier varieties having six-wheel drive, otherwise another tractor unit would have to be used. The heavy haulage variants of tractor-units are often turned into a ballast tractor by fitting temporary ballast, because their chassis allows a high BDM which may go beyond the legal limit, hence requiring special permits. A tractor unit can sometimes have a mounted crane located behind the cab. The tractor unit can still pull a trailer using its fifth wheel, although it will carry less payload, due to the extra bulk of the crane. A crane truck is able to lift its load on site, and usually comes with stabilisers like those on mobile cranes. These cranes can come in sizes from a few tonnes - up to special heavy-duty ones that can lift in excess of 80 ton/mtr][ - for lifting intermodal containers and office units. Unlike a rigid truck with a crane, the tractor and crane have the advantage that they can be separated and repositioned relative to the load if necessary. In the European Union and non-EU countries that have signed the ADR agreement, tractor units which haul tankers carrying flammable liquids must be specially modified to reduce the fire risk. This includes using a fully insulated electrical system (neither side earthed to the frame), relocation of exhaust components, and enclosing all wiring in conduit. Additional requirements include mandatory ABS on both the tractor and the trailer, additional 6-kilogram (13 lb) fire extinguishers for putting out a fire in the tanker, leak containment equipment, etc. In countries that have signed the ADR agreement, a driver is required to have special training for hauling dangerous goods (including flammable liquids) in tanks. This is a supplement to the main ADR training certificate. In the USA and Australia in particular, owner drivers, and even fleet operators, go to great lengths to customise their vehicle in a similar fashion to a custom car. This involves fitting larger exhaust systems (often highly polished stainless steel or chrome plating), extra lights and custom paint, among other things. Such tractor units attract lots of attention, and can be beneficial for promoting their businesses; such tractors can be matched with customised trailers. Some companies have one custom truck, or at least one tractor unit that is different, or more powerful, than the rest, to act as their flagship.
Two-wheel tractor or walking tractor are generic terms understood in the USA and in parts of Europe to represent a single-axle tractor, which is a tractor with one axle, self-powered and self-propelled, which can pull and power various farm implements such as a trailer, cultivator or harrow, a plough, or various seeders and harvesters. The operator usually walks behind it or rides the implement being towed. Similar terms are mistakenly applied to the household rotary tiller or power tiller that may be wheeled and/or self-propelled but often is not. A further distinction is seen in the two-wheeled tractor's ability to operate disparate types of agricultural equipment, while rotary tillers are smaller and specialize in soil tillage. This article concerns two-wheeled tractors as distinguished from such tillers. Research has identified a number of terms used to identify two-wheel tractors, including "iron-ox; walking tractor; Kubota; mechanical ox; ox-machine; power tiller; rotary hoe, rotary plough, rotary tiller; Rotavator, [and] tok-tok". "Power tiller" can be understood as a garden tiller/rototiller of the small (3–7 hp or 2.2–5.2 kW) petrol/gasoline/electric powered, hobby gardener variety; they are often sold as a rotary tiller, though the technical agricultural use of that term refers solely to an attachment to a larger tractor. Alternatively, the terms "power tiller" or "rotary tiller" are always understood in Asia and elsewhere to be rubber- or iron-wheeled, self-propelled machines of 5–18 hp (3.7–13 kW) and usually powered by heavy-duty single-cylinder diesel engines (many Asian countries historically have had a high luxury tax on petrol/gasoline). Adding to the nomenclature confusion, agricultural engineers like to classify them as single-axle tractors. For clarity, the rest of this article refers to the self-propelled, single-axle, multi-attachment tractive machines as two-wheel tractors. For production agriculture, past and present, two-wheel tractors are offered with wide range attachments such as rotovators, moldboard, disc-plow and spike-tooth harrows, seeders, transplanters, and planters. Even zero till/no-till planters and seeders have become available. In plant protection two-wheel tractor attachments consist of various inter-cultivators and sprayers. For harvesting mowers, reaper/grain harvesters, reaper-binders, and even combine harvesters are available for them. For transport, trailers with capacities from 0.5 to 5 plus ton cargoes are available, meaning they can execute practically all of the chores done by larger 4-wheel tractors. This confusion over, or perhaps just ignorance of the utility of 2-wheel tractors persists even at research and institutional levels. The United Nation's Food and Agriculture Organization's own statistical database, FAO Stat gauges levels of agricultural mechanization by numbers of 4-wheel tractors and ignores completely the fact that 2-wheel tractors often perform much, or even exactly, the same work as done by 4-wheeled models. By using FAO's statistics, international donors and agricultural research and development centres assume, as Bangladesh and Sri Lanka have very few 4-wheel tractors, that they are completely unmechanized compared to (e.g.) India, which has a large population of them (besides 100,000 two-wheel tractors][). Yet, when two-wheel tractors are included, Bangladesh and Sri Lanka are the most highly mechanized countries in south Asia in terms of area farmed using mechanized tillage. In 1910 Dr. Konrad von Meyenburg of Basel, Switzerland, applied for a patent for a "Machine for Mechanical Tillage" Patent Number 1,018,843 was granted on February 27, 1912. He then licensed his patent to Siemens-Schuckertwerke of Berlin, Germany. Siemens an electrical manufacturer built their first two-wheel tractor with rotovator Bodenfräse (rotovator or literally soil grinder) using an electric motorized two-wheel tractor and a long extension cord in 1911. The idea was quickly abandoned and Siemens began using two and four cycle single cylinder internal combustion engines to power their two-wheel tractors. Around 1932 Siemens sold off its cultivator division and focus on its electrical applications. Mr. Eberhard Bungartz of Munich, Germany, a trailer manufacturer, purchased the division in 1934 with all patents, parts, and machinery, and he went into production using the Bungartz name. THE SIMAR Co. (Société Industrielle de Machines Agicoles Rotatives) of Switzerland began development of a similar machine and by 1932 were producing several size machines ranging from 2½ to 10 horsepower, with a tilling width of 14" to 36", and weight from 220 to 880 pounds. Two-wheel tractors existed in the U.S. at least as early as 1913, when the Detroit Tractor Company advertised a tractor whose operator, riding on the implement, controlled the tractor via reins, just as he would a horse team. By 1918, the Moline Plow Company's Moline Universal Tractor likewise relied on its implement to supply the rear wheels in a four-wheel articulated unit, though its design dispensed with the long trailer tongue and horse reins. A 1918 example of Moline advertising called the Universal "the original two-wheel tractor", which was a fanciful claim in light of the Detroit Tractor and other machinery described with that phrase from 1913 through 1915. But Moline Plow no doubt felt pressured to claim priority in response to a very similarly built competitor, the Allis-Chalmers Model 6-12, which Moline Plow alleged was a patent-infringing copy. As early as 1911, Benjamin Franklin Gravely of Charleston West Virginia began with connecting the Indian motorcycle to a manually operated push plow. In 1916 he incorporated and, after obtaining partners, began producing single-wheel tractors and attachments under the name Gravely Tractor. The Model "D" Gravely Power Plow, like the prototype, was a single-wheeled affair, with a 2 horsepower (1.5 kW) air-cooled engine. It wasn't until 1937 that Gravely would introduce the Model L two-wheeled tractor with a 5 horsepower (3.7 kW) engine. Through the 20th century, Gravely became arguably one of the most successful and recognizable two-weeled tractors produced in the United States, at one point offering 120 individual attachments for their all-gear drive machines. In 1915, Rush Hamilton of Healdsville, California, designed grouser drive wheels for his tractor, which came with an articulated two-iron-wheeled sulky to which wagons or plows could be attached. It was about this time that he formed the Hamilton Tractor Company. About 10 years later, the wheels were called "Hamilton wheels" when used on a Fordson tractor. In 1916 he helped form the Fageol Motors Company, where he assisted in the development of the Fageol tractor. In 1932, Mando "Steve" Ariens, having just taken over the reins of his fathers' Brillion Iron Works, had to declare bankruptcy at the height of the Great Depression. In 1933, in his father Henry's garage and Steve's basement, he and his father developed their first Ariens Rotary Tiller, a 30" tiller, powered by a 14 hp (10 kW), front-mounted, four-cylinder V-type engine. In 1930, automobile manufacturer Cadwallader Washburn "Carl" Kelsey was introduced to the rototiller by H.B. Hiller, a German immigrant who once worked for Siemens' "boden frasen" division. Kelsey opened a sales office using the name Rototiller Co. on Broadway in New York City. He then started importing Siemens boden frasen from Germany. In 1932, Kelsey incorporated using the new company name Rototiller, Inc. and the "Rototiller" trademark (Kelsey didn't coin the name 'Rototiller' it was already being used in Europe). The operation was moved to Long Island City, NY. and SIMAR from Switzerland was added to the line. Carl Kelsey designed, patented and made several improvements to the SIMAR and Siemens machines because of the different American soils versus the European soil that had been farmed for many more centuries. One major improvement was a shock absorber to reduce tine spring return bounce. In 1934 Kelsey and Rototiller, Inc. introduced its first rotary tiller of its own design, the Model AA All-American. And in 1937 Rototiller, Inc. moved from its Long Island City facility to 102nd Street and 9th Avenue in Troy, New York. In 1945 after selling the larger B-series Rototillers and trademark to Graham-Paige Motors, Rototiller, Inc. converted to full-time production of various models of small horsepower home garden size rototillers. In 1946, Cecil Pond of South Bend, Indiana, started the Wheel Horse Company, whose first product was a walk-behind two-wheel tractor. In quick succession in 1959 and 1960, Rototiller traded hands to Porter Cable Company of Syracuse, New York, and then to Rockwell Manufacturing Company of Pittsburgh, Pennsylvania. The rear-tine rototiller business continued to decline and Porter-Cable sold its Rototiller and small engine division to Moto-Mower Division (Richmond, Indiana) of the Dura Corp. of Detroit (formerly Detroit Harvester) according to a May 10, 1962 article in the Richmond Palladium-Item & Sun-Telegram. In 1961 Rototiller, Inc. and the Roto-Ette trademark disappeared. Today, the Ariens Company continues, and Gravely is now a subsidiary of Ariens. Japanese entrepreneurs began to indigenously design and manufactured two-wheel tractors in the early 1920s. According to Francks (1996) an Okayama farmer Nishizaki Hiroshi (b. 1897) was returning from the WWI determined not to walk behind his father's draft animals and began experimenting with attaching a plow to the newly available small horsepower kerosene engines that farmers were beginning to use for pumping water and threshing. Nishazaki saw a Swiss made garden tractor (? SIMAR ?- Société Industrielle de Machines Agicoles Rotatives ) being demonstrated through a Japanese government technology demonstration initiative in a nearby village (The Japanese agent of the Swiss machine company stopped importing by 1925 as the machine reportedly proved not capable of handling Japanese heavy rice soils). By 1926 Nishizaki had made his first version from diesel powered engine connected by a belt to rotating blades mounted on a wooden frame with two wheels. Soon he began renting it out to neighbors. And as with all good ideas soon local multiple small workshops entered the scene producing various versions. By 1938 there were 22 manufacturers in Japan with 17 of them in Okayama. By 1939 there were over 2800 two-wheel tractors/rotovators in use in Japan. But by the early 1940s nearly half of all the machines were out of commission due to lack of quality and spare parts. After WWII small 2-wheel tractors were imported from the United States and were mainly intended for use in transportation/pulling carts and small trailers. As these gained popularity many Japanese manufacturers "...taking hints gleaned from foreign machines..." started production using the American as their initial model (Francks 1996: 789). Farmers quickly found that 2-wheel tractors were more economical to use, as compared to keeping animals for tillage and 2-wheel tractors began selling widely. Agricultural machinery dealers received cattle for the barter for tractors and they and in turn sold the cattle in the meat market. Average tractor horsepower per hectare in 1950 was nearly zero. This average grew to 0.86 PS per hectare within ten years with the rapid spread of 2-wheel tractors. Trailer attachments were also being widely utilized for transportation. Matsuyamasuki, presently known as Niplo brand, invented the Japanese style mold board plow to be attached to 2-wheel tractor, that made plowing with a moldbard possible with 2.5 horsepower (1.9 kW) tractors. Though four-wheel "riding" tractors began to spread in 1960s, and are taking over primary tillage operations, 2-wheel tractors are still popular in Japan for primary tillage and inter-cultivation in vegetable production, transportation around the farm, etc. Most farm households that own a 4-wheel tractor also own at least one 2-wheel tractor. The unique long-handled "Thai" type two-wheel tractor was developed in the late 1950s by M.R. Debriddhi Devakul (M.R. stands for Mom Rajawong, meaning that his great-grandfather was the King of Thailand, and that he could be properly addressed as "Prince"), head of the Engineering Division of the Thai Rice Department, of the Thai Ministry of Agriculture and Cooperatives. The long handles were made for turning the tractor more easily in wet rice fields. Initially, the tractor had no differential or steering clutches and the engines were kerosene pumping engines. As the popularity of the tractor became obvious (known as the "Iron Buffalo"), three Japanese firms set up diesel engine factories in Thailand with agreements to progressively increase local content, which is now nearly 100%. Kubota was the most successful of these three. The tractor was made by many local workshops – everyone copying from each other – and competing for sales to the point that the tractor without engine was very inexpensive, about one third to one half the cost of the engine. Attachments were moldboard and disc plows, harrows, trailed-type rotary puddlers (lateral drums with protruding paddles), and trailers. The tractor eventually evolved into a more complex standard "NC" model with three gears forward, one reverse, and steering clutches. Until recently (2010) the Thai models had no power takeoff (PTO), off the transmission, but many farmers use V-belts to connect the stationary tractor engine to power water pumps, etc. A new NC Plus model offered by Siam Kubota now comes with a PTO that can drive a rotary tiller and other attachments. The tractors are still made by several Thai companies but recently inexpensive Chinese-made NC models have come on the market. Through the 1980s and 1990s, more than 50,000 tractors were reportedly being produced and sold each year. In 1955, Ray Wijewardene designed a two-wheel tractor. An early attempt to mechanize farm labour during the Green Revolution, it was eventually manufactured and marketed worldwide by the Landmaster company in Nottingham, UK. By 1975 nearly 11,000 units had been imported. By 2001, over 2,000 mostly Chinese 2WTs were being imported per year and by 2007 it was estimated that there were over 125,000 2WTs in Sri Lanka. Interest in two-wheel tractors in India began with special government programs in the 1960s that aided in setting up multiple joint ventures with Japanese two-wheel tractor manufacturers. Initial government prospects for two-wheel tractors was very high (targets were set at 100,000 two-wheel tractors sold per year by mid-1970s). To meet these expectations the Government of India expanded its efforts to include government subsidies, and greatly increased research, development and extension programs for two-wheel tractors. Despite these efforts two-wheel tractor adoption has been disappointing. Especially so when current number of two-wheel tractors estimated at 100,000 are compared with neighboring Sri Lanka's and Bangladesh's two-wheel tractor populations of 120,000 and 400,000 respectively- countries that are a fraction the size of India but with very similar agricultural and socio-economic systems. There have been many reasons offered and even official investigations into the low adoption rates. One main reason given here is that prices of the joint venture Indian-Japanese two-wheel tractors are twice as expensive as compared to the nearly identical Chinese made two-wheel tractors available in Sri Lanka and Bangladesh. Indian manufactures that did not survive are: JK Satoh Agricultural Machinery Ltd. a collaboration between JK Cotton Spinning and Weaving Mills Ltd (based in Kanpur, UP) and Satoh Agricultural Machinery Ltd., Japan, began production of two-wheel tractors in a plant with a capacity of 6000 units per year but from its beginning in 1972 till closure of the plant in 1977 only produced and sold 800 units. History of two-wheel tractors began with efforts in the late 1970s to promote Japanese imported two-wheel tractors. Adoption remained low through most of the 1980s. In 1987 a large cyclone killed much of the livestock and bullock population. With no prospect timely restoration the bullock population the government began to allow what they once considered inferior quality Chinese two-wheel tractors to be imported to aid in fulfilling farmers land preparation needs. Chinese two-wheel tractors were 50% less cost than the comparable Japanese or Indian manufactured two-wheel tractors and adoption quickly increased, to over 100,000 by 1993, 200,000 by late 1990s and some current estimates put the number at well over 300,000 Chinese two-wheel tractors. Though there has been some criticism on the high cost of imports, others have noted that there is now a very large spare parts industry in support of the Chinese imports. China has the highest numbers that are estimated to approach 10 M, Using tractor engine replace truck engine to save cost is a good way in China, making a tripper tractor is accepted by Chinese and working in mine area and construction site. Thailand has nearly 3 M, Sri Lanka 120,000, Nepal 15,000. Parts of Africa have begun importing Chinese tractors and Nigeria may have close to 1,000. Southern Germany, northern and southern Italy, and many countries of central Europe also have significant populations of 2-wheel tractors. A number of reports have highlighted safety issues associated with the operation of two-wheel tractors. The most common accidents involve crossing the bunds and road transport. The operation of two-wheel tractors for transport at night is a recognised hazard in many countries, particularly as single headlights can be mistaken for a motorcycle. Research undertaken in Cambodia and Laos concluded that two-wheel tractors are involved in around five per cent of fatal accidents. Occupational health and safety reports have recommended regular breaks for the machine operator due to vibrations. However, safety researchers have concluded that "the risk to public safety must be weighed against the economic and social benefits." Located in Changzhou, Jiangsu Provence near Shanghai Changzhou Dongfeng Agricultural Machinery Group Co. claims to be the only manufacturer in China that owns the Dong Feng brand name. Manufacturing more than 150,000 two-wheel tractors a year in 8, 12, 14 and 15 hp (11 kW) ranges, it has recently expanded into the 4-wheel tractor market manufacturing over 30,000 tractors in the 20–90 hp (15–70 kW) range, under the brand name CHANGTUO. From 9 hp-20 hp, millions of two-wheel tractors (called the Walking Tractor often in China) are working in Asia's small farms & gardens. There is also a smaller type (6-9 hp) called the Mini Tiller (2 wheel walk behind). It can be widely used in the hills, mountains, greenhouses, gardens, paddy fields, and meets a variety of different geographical agronomic needs. Located in Huai'An, Jiangsu Provence near Shanghai. It claims to sell a tripper tractor which is mutli-functional. The tripper tractor is used for mining areas and construction sites, providing good traction in muddy and uneven road conditions. Performance is better than a mini-truck, has a low price, and is easy to use and maintain. Power units from 24HP to 42HP are available, with the 24HP engine more commonly used and preferred by users. Located in Kerala in southern India, KAMCO in cooperation with Kubota, Japan, manufacturers 12 hp (8.9 kW) two-wheel tractor with a range of attachments, a two-wheel tractor walk behind 3.5 hp 120 centimeter reaper and a small 5 hp (3.7 kW) [1]. It currently sells nearly 6500 of its 2-wheel tractors per year. Located in Bangalore, VST Tiller Tractors Ltd, part of the VST Group [2] in 1965, in association and joint venture with the Mitsubishi Group, Japan, began production production of single cylinder diesel engines and two-wheel tractors. Currently they offer three versions of its VST Shakti brand two-wheel tractors with rotary tillers. The 13 hp (9.7 kW) VST Shakti 130DI/CT85, the 9 hp (6.7 kW) Mitsubishi Shakti VWH 120/ CT85, and 8 hp (6.0 kW) Mitsubishi Shakti AD 8V/CT85. In 2003 they also began importing Siafeng type 2-wheel tractors from China and marketing them under their Shakti Brand. Located in Bangkok, Thailand, Siam Kubota Industry Co.,Ltd. is a joint venture between The Siam Cement Pcl., Kubota Corporation, Marubeni Corporation, and Min Sen Machinery Co.,Ltd. than began operations in 1978 [3]. They make a range of havesters, 4-wheel tractors and 2-wheel tractors. They offer four models of walk behind (with out sulky seat) and with single and double (steering) clutches. Vikyno a manufacturer since 1967 of compact diesel engines, four-wheel (including Kubota under 35HP) and two-wheel tractors and agricultural machinery like rice mills and powered reapers. 2WTs models are: - MK55 + Gasoline Engine 168F. - MK70 + Diesel Engine RV70. - MK120S + Diesel Engine RV 125-2. - MK120 + Diesel Engine RV 125-2. - MK120B + Diesel Engine RV 125-2. - MK165 + Diesel Engine RV 165-2. Mayfield pedestrian tractors appeared on the market sometime about 1949 and were principally designed as a grass cutter in much the same vein as the Allen Scythe. Subsequently a comprehensive range of attachments were available to turn the tractor into a useful tool for the smallholder and market gardener. Assembly was carried out at the Balfour works of S R Wood & Co in Croydon but latterly moved to a site in Redhill, Surrey. Makers of two-wheel garden and farm two-wheel tractors with a variety of implements. The company was established in post-war Germany in the southwest of the country, in the federal state of Baden-Wurttemberg. The founder of the Mockmuhl Machine factory was Erwin Machtel, who, together with his partner and Technical Director Dr.Ing. Otto Gohler, managed in 1945 to re-locate the pre-war production line and materials of the Karlsruhe Gears Factory to the neighboring town of Ruchsen. In response to the local vintner needs of the time, Machtel and Gohler were encouraged to produce their first non-wheeled power hoe, a project which transported the name Mockmuhl all over the world. Soon the wheeled version followed. In 1948 the 100th machine was sold. In 1958 the 100,000th machine was unveiled at the German Agricultural Fair by the then Minister and later Prime Minister Dr. Lübke. In 2001 the one millionth machine was raffled to the public at the Cologne International Gardening Fair. It was one of the Model 100, which represents Agria's most popular model of power hoe. Grillo spa began in the Romagna region in the early 1950s developing a farm hoe for weeding in fruit orchards. In 1953 the first Grillo walking tractor was born. The Grillo winning idea was to detach the motorized tractor from the attachments. It became possible to fit tines, ploughs, and trailers, and via fitting a water pump it was possible to irrigate. In 1955 the factory started the first series production of 15 different models per year. In 1957 "Grillo" became the name of the factory (formerly Pinza) and a brand. In the 1980s the company experienced a considerable growth in the garden machines. In that decade the Grillo research and development department created the first Italian lawnmower with a double hydrostatic system. Today thousands of machines are sold throughout the world annually. BCS was founded in 1943 by Luigi Castoldi in his workshop in Abbiategrasso, a small town near Milan. The area was and still is highly agricultural. For this reason the motor-mower model 243 was created. This was among the first self-propelled motor-mowers in the world. At the end of the 1960s BCS entered the field of green maintenance machines by producing the first “light” multipurpose two-wheel tractors. Starting in 1970, BCS introduced rotary disc-mowers. In 1988 BCS purchased Ferrari at Luzzara and in 1999 BCS purchased Pasquali at Calenzano; these acquisitions strengthened BCS Group's divisions with two brands with an international reputation. BCS Group presently counts on three production plants (Abbiategrasso, Luzzara, and Cusago) and on six branches. BCS are makers of two-wheel and four wheel tractors targeting both agriculture and commercial lawn and greens care. Headquarter and factories are located in Abbiategrasso. Ferrari is a manufacturer of two and four wheel tractors devoted to agriculture and lawn care. It was created in 1954, during the agricultural reconstruction period of the country. After an initial period dedicated to the production of wire-drawing machines for irrigation pipes, in 1957 Ferrari took part in the Verona exhibition with its first agricultural machine: the two-wheel tractor MC 57, which carries the date of its birth. In 1965 Ferrari launched the first articulated tractor MT65. The range of products was increased to motor mowers and tractors for diverse applications. At the end of the 1960s, the company looked to foreign markets; the subsidiary company Ferrari France was established in 1972. In 1988 Ferrari became part of the BCS Group. Today Ferrari has a wide range of machines between maintenance machines for recreational use and professional tractors for niche agriculture. Headquarters and factories are located at Abbiategrasso. Founded in 1949 by Dr. Lino Pasquali, the company began production of two-wheel tractors, and in the late 1950s ergonomic improvements such as rubber tires, seat, and steering handles were added. In the late 1960s a line of articulated four-wheel tractors was added. In 1999, the BCS group purchased the Pasquali brand. Pasquali machines work all over the world, with a wide range of motor mowers, two-wheel tractors, and specialized tractors with power up to 100 hp. Headquarters and factories are located at Abbiategrasso. Established in 1916, Gravely Tractors began production of two-wheel tractor with moldboard plows costing approximately 170 USD and slowly grew to become one of the most recognized commercial lawn and garden machinery manufacturers in the US. In 1986 Gravely became a wholly owned subsidiary of the Ariens Company.
The M6 High-Speed Tractor was an artillery tractor used by the US Army in World War II to tow heavy artillery pieces such as 8 inch Gun M1 and 240 mm Howitzer M1. Media related to M6 High Speed Tractor at Wikimedia Commons
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially (and originally) tillage, but nowadays a great variety of tasks. Agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised. The word tractor was taken from Latin, being the agent noun of trahere "to pull". The first recorded use of the word meaning "an engine or vehicle for pulling wagons or ploughs" occurred in 1901, displacing the earlier term "traction engine" (1859). In Britain, Ireland, Australia, India, Spain, Argentina, Slovenia, Serbia, Croatia, and Germany, the word "tractor" usually means "farm tractor", and the use of the word "tractor" to mean other types of vehicles is familiar to the vehicle trade, but unfamiliar to much of the general public. In Canada and the US, the word may also refer to the road tractor portion of a tractor trailer truck, but also usually refers to the piece of farm equipment. The first powered farm implements in the early 19th century were portable engines – steam engines on wheels that could be used to drive mechanical farm machinery by way of a flexible belt. Around 1850, the first traction engines were developed from these, and were widely adopted for agricultural use. The first tractors were steam-powered plowing engines. They were used in pairs, placed on either side of a field to haul a plow back and forth between them using a wire cable. Where soil conditions permitted (as in the United States), steam tractors were used to direct-haul plows, but in the UK and elsewhere, plowing engines were used for cable-hauled plowing, instead. Steam-powered agricultural engines remained in use well into the 20th century until reliable internal combustion engines had been developed. In 1892, John Froelich invented and built the first gasoline/petrol-powered tractor in Clayton County, Iowa, USA. A Van Duzen single-cylinder gasoline engine was mounted on a Robinson engine chassis, which could be controlled and propelled by Froelich's gear box. After receiving a patent, Froelich started up the Waterloo Gasoline Engine Company, investing all of his assets, which by 1895, all would be lost and his business resigned to become a failure. After graduating from the University of Wisconsin, Charles W. Hart and Charles H. Parr developed a two-cylinder gasoline engine and set up their business in Charles City, Iowa. In 1903, the firm built 15 "tractors", a term with Latin roots coined by Hart and Parr, and a combination of the words traction and power. Their 14,000-pound #3 is the oldest surviving internal combustion engine tractor in the United States, and is on display at the Smithsonian National Museum of American History in Washington D.C. The two-cylinder engine has a unique hit-and-miss firing cycle that produced 30 horsepower at the belt and 18 at the drawbar. In Britain, the first recorded tractor sale was the oil-burning Hornsby-Ackroyd Patent Safety Oil traction engine, in 1897. However, the first commercially successful design was Dan Albone's three-wheel Ivel tractor of 1902. In 1908, the Saunderson Tractor and Implement Co. of Bedford introduced a four-wheel design, and went on to become the largest tractor manufacturer outside the U.S. at that time. While unpopular at first, these gasoline-powered machines began to catch on in the 1910s, when they became smaller and more affordable. Henry Ford introduced the Fordson, the first mass-produced tractor, in 1917. They were built in the U.S., Ireland, England and Russia, and by 1923, Fordson had 77% of the U.S. market. The Fordson dispensed with a frame, using the strength of the engine block to hold the machine together.][ By the 1920s, tractors with gasoline-powered internal combustion engines had become the norm. Tractors can be generally classified as two-wheel drive, two-wheel drive with front wheel assist, four-wheel drive (often with articulated steering), or track tractors (with either two or four powered rubber tracks). The classic farm tractor is a simple open vehicle, with two very large driving wheels on an axle below and slightly behind a single seat (the seat and steering wheel consequently are in the center), and the engine in front of the driver, with two steerable wheels below the engine compartment. This basic design has remained unchanged for a number of years, but enclosed cabs are fitted on almost all modern models, for reasons of operator safety and comfort. In some localities with heavy or wet soils, notably in the Central Valley of California, the "Caterpillar" or "crawler" type of tracked tractor became popular in the 1930s, due to superior traction and flotation. These were usually maneuvered through the use of turning brake pedals and separate track clutches operated by levers rather than a steering wheel. Four-wheel drive tractors began to appear in the 1960s. Some four-wheel drive tractors have the standard "two large, two small" configuration typical of smaller tractors, while some have four large, powered wheels. The larger tractors are typically an articulated, center-hinged design steered by hydraulic cylinders that move the forward power unit while the trailing unit is not steered separately. In the early 21st century, articulated or nonarticulated, steerable multitrack tractors have largely supplanted the Caterpillar type for farm use. Larger types of modern farm tractors include articulated four-wheel or eight-wheel drive units with one or two power units which are hinged in the middle and steered by hydraulic clutches or pumps. A relatively recent development is the replacement of wheels or steel crawler-type tracks with flexible, steel-reinforced rubber tracks, usually powered by hydrostatic or completely hydraulic driving mechanisms. The configuration of these tractors bears little resemblance to the classic farm tractor design. The predecessors of modern tractors, traction engines, used steam engines for power. Since the turn of the 20th century, internal combustion engines have been the power source of choice. Between 1900 and 1960, gasoline was the predominant fuel, with kerosene (the Rumely Oil Pull was the most notable of this kind) and ethanol being common alternatives. Generally, one engine could burn any of those, although cold starting was easiest on gasoline. Often, a small auxiliary fuel tank was available to hold gasoline for cold starting and warm-up, while the main fuel tank held whatever fuel was most convenient or least expensive for the particular farmer. Dieselisation gained momentum starting in the 1960s, and modern farm tractors usually employ diesel engines, which range in power output from 18 to 575 horsepower (15 to 480 kW). Size and output are dependent on application, with smaller tractors used for lawn mowing, landscaping, orchard work, and truck farming, and larger tractors for vast fields of wheat, maize, soy, and other bulk crops. Liquified petroleum gas (LPG) or propane also have been used as tractor fuels, but require special pressurized fuel tanks and filling equipment, so are less prevalent in most markets. In some countries such as Germany, biodiesel is often used. Some other biofuels such as straight vegetable oil are also being used by some farmers. Most older farm tractors use a manual transmission. They have several gear ratios, typically three to six, sometimes multiplied into two or three ranges. This arrangement provides a set of discrete ratios that, combined with the varying of the throttle, allow final-drive speeds from less than one up to about 25 miles per hour (40 km/h), with the lower speeds used for working the land and the highest speed used on the road. Slow, controllable speeds are necessary for most of the operations performed with a tractor. They help give the farmer a larger degree of control in certain situations, such as field work. However, when travelling on public roads, the slow operating speeds can cause problems, such as long queues or tailbacks, which can delay or annoy motorists in cars and trucks. These motorists are responsible for being duly careful around farm tractors and sharing the road with them, but many shirk this responsibility, so various ways to minimize the interaction or minimize the speed differential are employed where feasible. Some countries (for example the Netherlands) employ a road sign on some roads that means "no farm tractors". Some modern tractors, such as the JCB Fastrac, are now capable of much higher road speeds of around 50 mph (80 km/h). Older tractors usually have unsynchronized transmission designs, which often require the operator stop the tractor to shift between gears. This mode of use is inherently unsuited to some of the work tractors do, and has been circumvented in various ways over the years. For existing unsynchronized tractors, the methods of circumvention are double clutching or power-shifting, both of which require the operator to rely on skill to speed-match the gears while shifting, and are undesirable from a risk-mitigation standpoint because of what can go wrong if the operator makes a mistake – transmission damage is possible, and loss of vehicle control can occur if the tractor is towing a heavy load either uphill or downhill – something that tractors often do. Therefore, operator's manuals for most of these tractors state one must always stop the tractor before shifting, and they do not even mention the alternatives. As already said, that mode of use is inherently unsuited to some of the work tractors do, so better options were pursued for newer tractor designs. In these, unsynchronized transmission designs were replaced with synchronization or with continuously variable transmissions (CVTs). Either a synchronized manual transmission with enough available gear ratios (often achieved with dual ranges, high and low) or a CVT allow the engine speed to be matched to the desired final-drive speed, while keeping engine speed within the appropriate speed (as measured in rotations per minute or rpm) range for power generation (the working range) (whereas throttling back to achieve the desired final-drive speed is a trade-off that leaves the working range). The problems, solutions, and developments described here also describe the history of transmission evolution in semi-trailer trucks. The biggest difference is fleet turnover; whereas most of the old road tractors have long since been scrapped, many of the old farm tractors are still in use. Therefore, old transmission design and operation is primarily just of historical interest in trucking, whereas in farming it still often affects daily life. The power produced by the engine must be transmitted to the implement or equipment to do the actual work intended for the equipment. This may be accomplished via a drawbar or hitch system if the implement is to be towed or otherwise pulled through the tractive power of the engine, or via a pulley or power takeoff system if the implement is stationary, or a combination of the two. Until the 1950s, plows and other tillage equipment usually were connected to the tractor via a drawbar, or a proprietary connecting system. The classic drawbar is simply a steel bar attached to the tractor (or in some cases, as in the early Fordsons, cast as part of the rear transmission housing) to which the hitch of the implement was attached with a pin or by a loop and clevis. The implement could be readily attached and removed, allowing the tractor to be used for other purposes on a daily basis. If the tractor was equipped with a swinging drawbar, then it could be set at the center or offset from center to allow the tractor to run outside the path of the implement. The drawbar system necessitated the implement having its own running gear (usually wheels) and in the case of a plow, chisel cultivator or harrow, some sort of lift mechanism to raise it out of the ground at turns or for transport. Drawbars necessarily posed a rollover risk depending on how the tractive torque was applied. The Fordson tractors (of which more units were produced and placed in service than any other farm tractor) was extremely prone to roll over backwards due to an excessively short wheelbase. The linkage between the implement and the tractor usually had some slack which could lead to jerky starts and greater wear and tear on the tractor and the equipment. Drawbars were appropriate to the dawn of mechanization, because they were very simple in concept and because as the tractor replaced the horse, existing horse-drawn implements usually already had running gear. As the history of mechanization progressed, however, the advantages of other hitching systems became apparent, leading to new developments (see below). Depending on the function for which a tractor is used, though, the drawbar is still one of the usual means of attaching an implement to a tractor (see photo at left). Some tractor manufacturers produced matching equipment that could be directly mounted on the tractor. Examples included front-end loaders, belly mowers, row crop cultivators, corn pickers and corn planters. In most cases, these fixed mounts were proprietary and unique to each make of tractor, so an implement produced by John Deere, for example, could not be attached to a Minneapolis Moline tractor. Another disadvantage was mounting usually required some time and labor, resulting in the implement being semipermanently attached with bolts or other mounting hardware. Usually, it was impractical to remove the implement and reinstall it on a day-to-day basis. As a result, the tractor was unavailable for other uses and dedicated to a single use for an appreciable period of time. An implement generally would be mounted at the beginning of its season of use (such as tillage, planting or harvesting) and removed only when the likely use season had ended. The drawbar system was virtually the exclusive method of attaching implements (other than direct attachment to the tractor) before Harry Ferguson developed the three-point hitch. Equipment attached to the three-point hitch can be raised or lowered hydraulically with a control lever. The equipment attached to the three-point hitch is usually completely supported by the tractor. Another way to attach an implement is via a quick hitch, which is attached to the three-point hitch. This enables a single person to attach an implement quicker and put the person in less danger when attaching the implement. The three-point hitch revolutionized farm tractors and their implements. Almost every tractor today features Ferguson's three-point linkage or a derivative of it. This hitch allows for easy attachment and detachment of implements while allowing the implement to function as a part of the tractor, almost as if it were attached by a fixed mount. Previously, when the implement hit an obstacle, the towing link would break or the tractor could flip over. Ferguson's genius was to combine a connection via two lower and one upper lift arms that were connected to a hydraulic lifting ram. The ram was, in turn, connected to the upper of the three links so the increased drag (as when a plough hits a rock) caused the hydraulics to lift the implement until the obstacle was passed. Other manufacturers copied Ferguson's invention, or developed variations of it. For example, International Harvestor's Farmall tractors had a two-point "Fast Hitch" and John Deere had a power lift that was similar to, but not as flexible as the Ferguson invention. Recently, Bobcat's patent on its front loader connection (inspired by these earlier systems) has expired, and compact tractors are now being outfitted with quick-connect attachments for their front-end loaders. In addition to towing an implement or supplying tractive power through the wheels, most tractors have a means to transfer power to another machine such as a baler, swather, or mower. Unless it functions solely by pulling it through or over the ground, a towed implement needs its own power source (such as a baler or combine with a separate engine) or else a means of transmitting power from the tractor to the mechanical operations of the equipment. Early tractors used belts or cables wrapped around the flywheel or a separate belt pulley to power stationary equipment, such as a threshing machine, buzz saw, silage blower, or stationary baler. In most cases, it was not practical for the tractor and equipment to move with a flexible belt or cable between them, so this system required the tractor to remain in one location, with the work brought to the equipment, or the tractor to be relocated at each turn and the power set-up reapplied (as in cable-drawn plowing systems used in early steam tractor operations). Modern tractors use a power take-off (PTO) shaft to provide rotary power to machinery that may be stationary or pulled. The PTO shaft generally is at the rear of the tractor, and can be connected to an implement that is either towed by a drawbar or a three-point hitch. This eliminates the need for a separate, implement-mounted power source, which is almost never seen in modern farm equipment. Virtually all modern tractors can also provide external hydraulic fluid and electrical power to the equipment they are towing, either by hoses or wires. Modern tractors have many electrical switches and levers in the cab for controlling the multitude of different functions available on the tractor. Modern farm tractors usually have four or five foot-pedals for the operator on the floor of the tractor. The pedal on the left is the clutch. The operator presses on this pedal to disengage the transmission for either shifting gears or stopping the tractor. Some modern tractors have (or as optional equipment) a button on the gear stick for controlling the clutch, in addition to the standard pedal. Two of the pedals on the right are the brakes. The left brake pedal stops the left rear wheel and the right brake pedal does the same with the right side. This independent left and right wheel-braking augments the steering of the tractor when only the two rear wheels are driven. This is usually done when it is necessary to make a sharp turn. The split brake pedal is also used in mud or soft soil to control a tire spinning due to loss of traction. The operator presses both pedals together to stop the tractor. For tractors with additional front-wheel drive, this operation often engages the 4-wheel locking differential (diff-lock) to help stop the tractor when traveling at road speeds. The pedal furthest to the right is the foot throttle. Unlike in automobiles, it can also be controlled from a hand-operated lever ("hand throttle"). This helps provide a constant speed in field work. It also helps provide continuous power for stationary tractors that are operating an implement by shaft or belt. The foot throttle gives the operator more automobile-like control over the speed of the tractor for road work. This is a feature of more recent tractors; older tractors often did not have it. In the UK, foot pedal use to control engine speed while travelling on the road is mandatory. Some tractors, especially those designed for row-crop work, have a 'de-accelerator' pedal, which operates in the reverse fashion to an automobile throttle, in that the pedal is pushed down to slow the engine. This allows fine control over the speed of the tractor when maneuvering at the end of crop rows in fields- the operating speed of the engine is set using the hand throttle, and to slow the tractor to turn, the operator simply has to press the pedal, and turn and release it once the turn is completed, rather than having to alter the setting of the hand throttle twice during the maneuver. A fifth pedal is traditionally included just in front of the driver's seat to operate the rear differential lock (diff-lock), which prevents wheel slip. The differential normally allows the outside wheel to travel faster than the inside wheel during a turn. However, in low-traction conditions on a soft surface, the same mechanism could allow one wheel to slip, further reducing traction. The diff-lock overrides this, forcing both wheels to turn at the same speed, reducing wheel slip and improving traction. Care must be taken to unlock the differential before turning, usually by hitting the pedal a second time, since the tractor with good traction cannot perform a turn with the diff-lock engaged. In modern tractors, this pedal is replaced with an electrical switch. Many functions once controlled with levers have been replaced with some model of electrical switch with the rise of indirect computer controlling of functions in modern tractors. Until the beginning of the 1960s, tractors had a single register of gears, hence one gear stick, often with three to five forward gears and 1 reverse. Then, group gears were introduced, and another gear stick was added. Later, control of the forward-reverse direction was moved to a special stick attached at the side of the steering wheel, which allowed forward or reverse travel in any gear. Nowadays, with CVTs or other clutch-free gear types, fewer sticks control the transmission, and some are replaced with electrical switches or are totally computer-controlled. The three-point hitch was controlled with a lever for adjusting the position, or as with the earliest ones, just the function for raising or lowering the hitch. With modern electrical systems, it is often replaced with a potentiometer for the lower bound position and another one for the upper bound, and a switch allowing automatic adjustment of the hitch between these settings. The external hydraulics also originally had levers, but now are often replaced with some form of electrical switch; the same is true for the power take-off shaft. Agriculture in the United States is one of the most hazardous industries, only surpassed by mining and construction. No other farm machine is so identified with the hazards of production agriculture as the tractor. Tractor-related injuries account for approximately 32% of the fatalities and 6% of the nonfatal injuries in agriculture. Over 50% is attributed to tractor overturns. The roll-over protection structure (ROPS) and seat belt, when worn, are the most important safety devices to protect operators from death during tractor overturns. Modern tractors have a ROPS to prevent an operator from being crushed if the tractor turns over. The ROPS does not prevent tractor overturns; rather, it prevents the operator from being crushed during an overturn. This is especially important in open-air tractors, where the ROPS is a steel beam that extends above the operator's seat. For tractors with operator cabs, the ROPS is part of the frame of the cab. A ROPS with enclosed cab further reduces the likelihood of serious injury because the operator is protected by the sides and windows of the cab. These structures were first required by legislation in Sweden in 1959. Before they were required, some farmers died when their tractors rolled on top of them. Row-crop tractors, before ROPS, were particularly dangerous because of their 'tricycle' design with the two front wheels spaced close together and angled inward toward the ground. Some farmers were killed by rollovers while operating tractors along steep slopes. Others have been killed while attempting to tow or pull an excessive load from above axle height, or when cold weather caused the tires to freeze to the ground, in both cases causing the tractor to pivot around the rear axle. For the ROPS to work as designed, the operator must stay within its protective frame. This means the operator must wear the seat belt; not wearing it may defeat the primary purpose of the ROPS. The most common use of the term "tractor" is for the vehicles used on farms. The farm tractor is used for pulling or pushing agricultural machinery or trailers, for plowing, tilling, disking, harrowing, planting, and similar tasks. A variety of specialty farm tractors have been developed for particular uses. These include "row crop" tractors with adjustable tread width to allow the tractor to pass down rows of corn, tomatoes or other crops without crushing the plants, "wheatland" or "standard" tractors with fixed wheels and a lower center of gravity for plowing and other heavy field work for broadcast crops, and "high crop" tractors with adjustable tread and increased ground clearance, often used in the cultivation of cotton and other high-growing row crop plant operations, and "utility tractors", typically smaller tractors with a low center of gravity and short turning radius, used for general purposes around the farmstead. Many utility tractors are used for nonfarm grading, landscape maintenance and excavation purposes, particularly with loaders, backhoes, pallet forks and similar devices. Small garden or lawn tractors designed for suburban and semirural gardening and landscape maintenance also exist in a variety of configurations. Some farm-type tractors are found elsewhere than on farms: with large universities' gardening departments, in public parks, or for highway workman use with blowtorch cylinders strapped to the sides and a pneumatic drill air compressor permanently fastened over the power take-off. These are often fitted with grass (turf) tyres which are less damaging to soft surfaces than agricultural tires. Space technology has been incorporated into agriculture in the form of GPS devices, and robust on-board computers installed as optional features on farm tractors. These technologies are used in modern, precision farming techniques. The spin-offs from the space race have actually facilitated automation in plowing and the use of autosteer systems (drone on tractors that are manned but only steered at the end of a row), the idea being to neither overlap and use more fuel nor leave streaks when performing jobs such as cultivating. Several tractor companies have also been working on producing a driverless tractor. The durability and engine power of tractors made them very suitable for engineering tasks. Tractors can be fitted with engineering tools such as dozer blades, buckets, hoes, rippers, etc. The most common attachments for the front of a tractor are dozer blades or buckets. When attached to engineering tools, the tractor is called an engineering vehicle. A bulldozer is a track-type tractor with a blade attached in the front and a rope-winch behind. Bulldozers are very powerful tractors and have excellent ground-hold, as their main tasks are to push or drag. Bulldozers have been further modified over time to evolve into new machines which are capable of working in ways that the original bulldozer can not. One example is that loader tractors were created by removing the blade and substituting a large volume bucket and hydraulic arms which can raise and lower the bucket, thus making it useful for scooping up earth, rock and similar loose material to load it into trucks. A front-loader or loader is a tractor with an engineering tool which consists of two hydraulic powered arms on either side of the front engine compartment and a tilting implement. This is usually a wide-open box called a bucket, but other common attachments are a pallet fork and a bale grappler. Other modifications to the original bulldozer include making the machine smaller to let it operate in small work areas where movement is limited. Also, tiny wheeled loaders, officially called skid-steer loaders, but nicknamed "Bobcat" after the original manufacturer, are particularly suited for small excavation projects in confined areas. The most common variation of the classic farm tractor is the hoe, also called a hoe-loader. As the name implies, it has a loader assembly on the front and a backhoe on the back. Backhoes attach to a three-point hitch on farm or industrial tractors. Industrial tractors are often heavier in construction, particularly with regards to the use of steel grill for protection from rocks and the use of construction tires. When the backhoe is permanently attached, the machine usually has a seat that can swivel to the rear to face the hoe controls. Removable backhoe attachments almost always have a separate seat on the attachment. Backhoe-loaders are very common and can be used for a wide variety of tasks: construction, small demolitions, light transportation of building materials, powering building equipment, digging holes, loading trucks, breaking asphalt and paving roads. Some buckets have retractable bottoms, enabling them to empty their loads more quickly and efficiently. Buckets with retractable bottoms are also often used for grading and scratching off sand. The front assembly may be a removable attachment or permanently mounted. Often the bucket can be replaced with other devices or tools. Their relatively small frames and precise controls make backhoe-loaders very useful and common in urban engineering projects, such as construction and repairs in areas too small for larger equipment. Their versatility and compact size makes them one of the most popular urban construction vehicles. In the UK, the word "JCB" is sometimes used colloquially as a genericized trademark for any such type of engineering vehicle. The term JCB now appears in the Oxford English Dictionary, although it is still legally a trademark of J. C. Bamford Ltd. The term "digger" is also commonly used. A compact utility tractor (CUT) is a smaller version of an agricultural tractor, but designed primarily for landscaping and estate management tasks rather than for planting and harvesting on a commercial scale. Typical CUTs range from 20 to 50 horsepower (15-37 kW) with available power take-off (PTO) horsepower ranging from 15 to 45 hp (11-34 kW). CUTs are often equipped with both a mid-mounted and a standard rear PTO, especially those below 40 horsepower (30 kW). The mid-mount PTO shaft typically rotates at/near 2000 rpm and is typically used to power mid-mount finish mowers, front-mounted snow blowers or front-mounted rotary brooms. The rear PTO is standardized at 540 rpms for the North American markets, but in some parts of the world, a dual 540/1000 rpm PTO is standard, and implements are available for either standard in those markets. One of the most common attachment for a CUT is the front-end loader or FEL. Like the larger agricultural tractors, a CUT will have an adjustable, hydraulically controlled three-point hitch. Typically, a CUT will have four-wheel drive, or more correctly four-wheel assist. Modern CUTs often feature hydrostatic transmissions, but many variants of gear-drive transmissions are also offered from low priced, simple gear transmissions to synchronized transmissions to advanced glide-shift transmissions. All modern CUTs feature government-mandated roll over protection structures just like agricultural tractors. The most well-known brands in North America include Kubota, John Deere Tractor, New Holland Ag, Case-Farmall and Massey-Ferguson. Although less common, compact backhoes are often attached to compact utility tractors. Compact utility tractors require special, smaller implements than full-sized agricultural tractors. Very common implements include the box blade, the grader blade, the landscape rake, the post hole digger (or post hole auger), the rotary cutter (slasher or a brush hog), a mid- or rear-mount finish mower, a broadcast seeder, a subsoiler and the rototiller (rotary tiller). In northern climates, a rear-mounted snow blower is very common; some smaller CUT models are available with front-mounted snow blowers powered by mid-PTO shafts. Implement brands outnumbere tractor brands, so CUT owners have a wide selection of implements. For small-scale farming or large-scale gardening, some planting and harvesting implements are sized for CUTs. One- and two-row planting units are commonly available, as are cultivators, sprayers and different types of seeders (slit, rotary and drop). One of the first CUTs offered for small farms of three to 30 acres and for small jobs on larger farms was a three-wheeled unit, with the rear wheel being the drive wheel, offered by Sears & Roebuck in 1954 and priced at $598 for the basic model. A row-crop tractor is tailored specifically to the growing of crops grown in rows, as in truck farming, and most especially to cultivating. Cultivating can take place anytime from soon after the crop plants have sprouted until soon before they are harvested. Several rounds of cultivating may be done over the season. A row-crop tractor essentially brings together a farm tractor and its cultivator into one machine, in the same way motive power has been combined into other machinery (for example, horseless carriages combined the motive power into transport vehicles; self-propelled guns combined the artillery tractor and its gun into one machine). The earliest win from introducing tractors to mechanize agriculture was in reducing the heavy efforts of plowing and harrowing before planting, which could often be (almost literally) backbreaking tasks for humans and draft animals. Early tractors were used mainly to alleviate this drudgery, but they tended to be very big and heavy, so were not well-suited to getting into a field of already-planted row crops to do weed control. Row-crop tractors—light, affordable, and reliable—corrected this flaw. The row-crop tractor category evolved rather than appearing overnight, but the International Harvester (IH) Farmall is often considered the "first" tractor of the category. Some earlier tractors of the 1910s and 1920s approached the form factor from the heavier side, as did motorized cultivators from the lighter side, but the Farmall brought all of the salient features together into one package, with a capable distribution network to ensure its commercial success. In the new form factor that the Farmall popularized, the cultivator was mounted in the front so it was easily visible. Additionally, the tractor had a narrow front end; the front tires were spaced very closely and angled in towards the bottom. The back wheels straddled two rows, and the unit could cultivate four rows at once. From 1924 until 1963, Farmalls were the largest selling row-crop tractors. To compete, John Deere designed the Model C, which had a wide front and could cultivate three rows at once. Only 112 prototypes were made, as Deere realized sales would be lost to Farmall if their model did less. In 1928, Deere released the Model C anyway, only as the Model GP (General Purpose) to avoid confusion with the Model D when ordered over the then unclear telephone. Oliver refined its "Row Crop" model early in 1930. Until 1935, the 18-27 was Oliver–Hart-Parr's only row-crop tractor. Many Oliver row-crop models are referred to as "Oliver Row Crop 77", "Oliver Row Crop 88", etc. Many early row-crop tractors had a tricycle design with two closely spaced front tires, and some even had a single front tire. This made it dangerous to operate on the side of a steep hill; as a result, many farmers died from tractor rollovers. Also, early row-crop tractors had no rollover protection system (ROPS), meaning if the tractor flipped back, the operator could be crushed. Sweden was the first country which passed legislation requiring ROPS, in 1959. Over 50% of tractor related injuries and deaths are attributed to tractor rollover. Canadian agricultural equipment manufacturer Versatile makes row-crop tractors that are 250 and 280 horsepower (190 and 210 kW); powered by an 8.3 liter Cummins Diesel engine. Modern row crop tractors have rollover protection systems in the form of a reinforced cab or a roll bar. Garden tractors (mini tractors) are small, light tractors designed for use in domestic gardens and small estates. Garden tractors are designed for cutting grass, snow removal, and small property cultivation. In the U.S., the term riding lawn mower today often is used to refer to mid- or rear-engined machines. Front-engined tractor layout machines designed primarily for cutting grass and light towing are called lawn tractors; heavier-duty tractors of similar size are garden tractors. Garden tractors are capable of mounting a wider array of attachments than lawn tractors. Unlike lawn tractors and rear-engined riding mowers, garden tractors are powered by horizontal-crankshaft engines with a belt-drive to transaxle-type transmissions (usually of four- or five-speeds, although some may also have two-speed reduction gearboxes, drive-shafts, or hydrostatic or hydraulic drives). Garden tractors from Wheel Horse, Cub Cadet, Economy (Power King), John Deere, Massey Ferguson and Case Ingersoll are built in this manner. The engines are generally a one- or two-cylinder petrol (gasoline) engines, although diesel engine models are also available, especially in Europe. Typically, diesel-powered garden tractors are larger and heavier-duty than gasoline-powered units and compare more similarly to compact utility tractors. Visually, the distinction between a garden tractor and a lawn tractor is often hard to make - generally, garden tractors are more sturdily built, with stronger frames, 12-inch or larger wheels mounted with multiple lugs (most lawn tractors have a single bolt or clip on the hub), heavier transaxles, and ability to accommodate a wide range of front, belly, and rear mounted attachments. Although most people think first of four-wheel vehicles when they think of tractors, a tractor may have one or more axles. The key benefit is the power itself, which only takes one axle to provide. Single-axle tractors, more often called two-wheel tractors or walk-behind tractors, have had many users since the beginning of internal combustion engine tractors. They tend to be small and affordable. This was especially true before the 1960s, when a walk-behind tractor could often be more affordable than a two-axle tractor of comparable power. Today's compact utility tractors and advanced garden tractors may negate most of that market advantage, but two-wheel tractors still enjoy a loyal following, especially where an already-paid-for two-wheel tractor is financially superior to a compact or garden tractor that would have to be purchased. Regions where two-wheel tractors are especially prevalent today include India, China, and Southeast Asia. Tractors tailored to use in fruit orchards typically have features suited to passing under tree branches with impunity. These include a lower overall profile; reduced tree-branch-snagging risk (via underslung exhaust pipes rather than smoke-stack-style exhaust, and large sheetmetal cowlings and fairings that allow branches to deflect and slide off rather than catch); spark arrestors on the exhaust tips; and often wire cages to protect the operator from snags. The ingenuity of farm mechanics, coupled in some cases with OEM or aftermarket assistance, has often resulted in the conversion of automobiles for use as farm tractors. In the United States, this trend was especially strong from the 1910s through 1950s. It began early in the development of vehicles powered by internal combustion engines, with blacksmiths and amateur mechanics tinkering in their shops. Especially during the interwar period, dozens of manufacturers (Montgomery Ward among them) marketed aftermarket kits for converting Ford Model Ts for use as tractors. (These were sometimes called 'Hoover wagons' during the Great Depression, although this term was usually reserved for automobiles converted to horse-drawn buggy use when gasoline was unavailable or unaffordable. During the same period, another common name was "Doodlebug"). Ford even considered producing an "official" optional kit. Many Model A Fords also were converted for this purpose. In later years, some farm mechanics have been known to convert more modern trucks or cars for use as tractors, more often as curiosities or for recreational purposes (rather than out of the earlier motives of pure necessity or frugality). During World War II, a shortage of tractors in Sweden led to the development of the so-called "EPA" tractor (EPA was a chain of discount stores and it was often used to signify something lacking in quality). An EPA tractor was simply an automobile, truck or lorry, with the passenger space cut off behind the front seats, equipped with two gearboxes in a row. When done to an older car with a ladder frame, the result was not dissimilar to a tractor and could be used as one. After the war it remained popular, now not as a farm vehicle, but as a way for young people without a driver's license to own something similar to a car. Since it was legally seen as a tractor, it could be driven from 16 years of age and only required a tractor license. Eventually, the legal loophole was closed and no new EPA tractors were allowed to be made, but the remaining ones were still legal, which led to inflated prices and many protests from people who preferred EPA tractors to ordinary cars. In March 1975, a similar type of vehicle was introduced in Sweden, the A tractor [from arbetstraktor (work tractor)]; the main difference is an A tractor has a top speed of 30 km/h. This is usually done by fitting two gearboxes in a row and not using one of them. The Volvo Duett was, for a long time, the primary choice for conversion to an EPA or A tractor, but since supplies have dried up, other cars have been used, in most cases another Volvo. Another type of homemade tractors are ones that are fabricated from scratch. The "from scratch" description is relative, as often individual components will be repurposed from earlier vehicles or machinery (e.g., engines, gearboxes, axle housings), but the tractor's overall chassis is essentially designed and built by the owner (e.g., a frame is welded from bar stock—channel stock, angle stock, flat stock, etc.). As with automobile conversions, the heyday of this type of tractor, at least in developed economies, lies in the past, when there were large populations of blue-collar workers for whom metalworking and farming were prevalent parts of their lives. (For example, many 19th- and 20th-century New England and Midwestern machinists and factory workers had grown up on farms.) Backyard fabrication was a natural activity to them (whereas it might seem daunting to most people today). The term "tractor" (US and Canada) or "tractor unit" (UK) is also applied to: Diesel-electric locomotive at work Komsomolets Soviet artillery tractor A Trackmobile 4150 Aircraft Pushback tractor An unusual application - road roller powered by a tractor-drive The First Tractor, a painting by Vladimir Krikhatsky. A single tractor in Brazil RT-M-160U model manufactured by Uralvagonzavod RT-M-160 model manufactured by Uralvagonzavod In addition to commercial manufacturers, the Open Source Ecology group has developed several working prototypes of an open source hardware tractor called the LifeTrac as part of its Global Village Construction Set.
Allis-Chalmers was a U.S. manufacturer of machinery for various industries. Its business lines included agricultural equipment, construction equipment, power generation and power transmission equipment, and machinery for use in industrial settings such as factories, flour mills, sawmills, textile mills, steel mills, refineries, mines, and ore mills. The first Allis-Chalmers Company was formed in 1901 as an amalgamation of the Edward P. Allis Company (steam engines and mill equipment), Fraser & Chalmers (mining and ore milling equipment), the Gates Iron Works (rock and cement milling equipment), and the industrial business line of the Dickson Manufacturing Company (engines and compressors). It was reorganized in 1912 as the Allis-Chalmers Manufacturing Company. During the next 70 years its industrial machinery filled countless mills, mines, and factories around the world, and its brand gained fame among consumers mostly from its farm equipment business's orange tractors. In the 1980s and 1990s a series of divestitures transformed the firm and eventually dissolved it. Its successors today are Allis-Chalmers Energy and AGCO. Author-photographer Randy Leffingwell (1993) aptly summarized the firm's origins and character. He observed that it "grew by acquiring and consolidating the innovations" of various smaller firms and building upon them; and he continued that "Metal work and machinery were the common background. Financial successes and failures brought them together." Former marketing executive Walter M. Buescher (1991) said that Allis-Chalmers "was a conglomerate before the word was coined." Whether or not it is literally true that Allis-Chalmers predated the sense of "conglomerate" meaning a widely diversified parent corporation, Buescher's point is valid: Allis-Chalmers, despite its common theme of machinery, was an amalgamation of disparate business lines, each with a unique marketplace, beginning in an era when consolidations within industries were fashionable but those across industries were not yet common. Edward P. Allis was an entrepreneur who in 1860 bought a bankrupt firm at a sheriff's auction, the Reliance Works of Milwaukee, Wisconsin, which had been owned by James Decker and Charles Seville. Decker & Seville were millwrights who made equipment for flour milling. Under Allis's management, the firm was reinvigorated and "began producing steam engines and other mill equipment just at the time that many sawmills and flour mills were converting to steam power." Although the financial panic of 1873 "caught Edward Allis overextended" and forced him into bankruptcy, "his own reputation saved him and reorganization came quickly," forming the Edward P. Allis Company. Leffingwell said, "He set out to hire known experts: George Hinkley, who perfected the band saw; William Gray, who revolutionized the flour-milling process through roller milling; and Edwin Reynolds, who ran the Corliss Steam Engine works." Allis died in 1889, but under his sons (Charles Allis and William Allis) and the other principals, the firm continued to prosper, and by 1900 it had grown to become one of America's largest steam engine builders. Thomas Chalmers was a Scottish immigrant to America who came to the U.S. about 1842. By 1844 he was at Chicago, Illinois and had found work with P.W. Gates, whose foundry and blacksmithing shops produced plows, wagons, and flour-milling equipment. The Gates firm "built the first steam-operated sawmill in the country at a time when Chicago was the leading producer of milled lumber in the country." In 1872, Thomas Chalmers founded the Fraser & Chalmers firm to manufacture mining machinery, boilers, and pumps. By 1880 steam engines were part of the product line and by 1890, the firm had become one of the world's largest manufacturers of mining equipment. Thomas Chalmers's son, William James Chalmers, was president of the company from circa 1890 to 1901. Meanwhile, the Gates Iron Works, with Chalmers family involvement, had become a manufacturer of crushers, pulverizers, and other rock and cement milling equipment. Another Scottish immigrant family, the Dickson family, came to Canada and the U.S. in the 1830s. By 1852, they had organized a small machine shop and foundry (Dickson & Company) in Scranton, Pennsylvania. In 1856 Thomas Dickson became its president, and in 1862 the firm incorporated as the Dickson Manufacturing Company. By 1900 they were building boilers, steam engines, locomotives, internal combustion engines, blowers, and air compressors. By 1901 the principals of the Edward P. Allis, Fraser & Chalmers, and Gates firms had decided to merge their companies. Edwin Reynolds believed Allis could control the industrial engine business. In May 1901 the Allis-Chalmers Company was formed. It acquired Dickson's industrial engine business. Dickson's locomotive business was rolled into the new locomotive consolidation, the American Locomotive Company (ALCO). The managing director of the new company was Charles Allis, his brother William was chairman of the board, and William J. Chalmers was deputy managing director. Shortly after the merger was completed, a new factory was built in an area west of Milwaukee that was then known as North Greenfield. In 1902, with this new factory, the locale was renamed West Allis, Wisconsin. With the combining of the constituent firms, Allis-Chalmers offered a wide array of pyrometallurgic equipment, such as blast furnaces and converters for roasting, smelting, and refining; ore milling equipment, various kinds of crushers and pulverizers, including stamp mills, roller mills, ball mills, conical mills, rod mills, and jigging mills; cyanidation mills and other concentration mills; hoisting engines; cars, including skip cars, slag cars, and general mine cars; briquetting plants; and the pumps, tanks, boilers, compressors, hydraulic accumulators, pipes, valves, sieves, and conveyors needed within these products. Like other firms that build capital equipment for industrial corporations, it also supplied consulting, erecting, and training services, such as helping a mining company to design a plant, to build its buildings and set up its machinery, and to teach the employees how to use and maintain it. In 1903, Allis-Chalmers acquired the Bullock Electric Company of Cincinnati, Ohio, which added steam turbines to Allis-Chalmers's powerplant equipment business line. By 1912, the Allis-Chalmers Company was in financial trouble, so it was reorganized. It was renamed the Allis-Chalmers Manufacturing Company, and Otto Falk, a former Brigadier General of the Wisconsin National Guard, was appointed to turn it around. Falk pushed for new products and new or expanded markets. Falk saw great growth potential in the mechanization of agriculture, which at the time was blossoming all over America. Allis-Chalmers's first farm tractors, the 10-18, the Model 6-12, and the Model 15-30, were developed and marketed between 1912 and 1919, and the farm implement line was expanded. As had also been true of the 1900–1920 period, the Roaring Twenties were a favorable time for consolidation and even conglomeration throughout the business world. It was also a time of strongly continuing mechanization on North American farms. At Allis-Chalmers, the 1920s brought yet more tractors, such as the 18-30, 12-20, 15-25, and the United tractor, a product built by Allis-Chalmers for a conglomerate that it was now a part of, the United Tractor & Equipment corporation. In 1926 Falk hired Harry Merritt, who would be a senior executive in Allis-Chalmers's tractor business for many years. Merritt had worked in the sales and marketing of various brands of farm and construction equipment, most recently Holt, when Falk hired him away. Buescher, who worked under Merritt, credited Merritt with turning around Allis-Chalmers's ailing farm equipment business and transforming it into the main profit center for the parent corporation. He said, "Some say that General Falk pulled Harry Merritt into Milwaukee to liquidate the ailing tractor division. Others say that he was brought in to breathe new life into the moribund and unprofitable operation. Even if the first appraisal is correct, the second proved to be the way it turned out. […] After Merritt's arrival, the profit picture changed. The farm equipment business proved to be a financial lifesaver for the corporation. […] From next to nothing in 1927, Merritt saw the percentage of farm equipment business go to just short of sixty percent of corporate sales." Also in 1926, Allis-Chalmers acquired Nordyke Marmon & Company of Indianapolis, Indiana, a maker of flour-milling equipment. In 1927, it acquired the Pittsburgh Transformer Company, a maker of electrical transformers. In 1928, Allis-Chalmers acquired the Monarch Tractor Company of Springfield, Illinois, thus adding a line of crawler tractors. In 1929, it acquired the La Crosse Plow Works of La Crosse, Wisconsin. The La Crosse Plow Works had a good-quality plow and various desirable implements, which now expanded the Allis-Chalmers implement line. Also in 1929, Harry Merritt was in California when the bright orange California poppy blossoms inspired him to think about the use of bright colors in marketing. Brightly colored things that can be seen from far away had potential in farm equipment marketing. He soon changed the paint color of Allis-Chalmers's tractors to Persian Orange, the available paint color that he felt most closely resembled the California poppy's color. Thus began the tradition of orange Allis-Chalmers tractors. Various competitors would follow suit over the next decade, as International Harvester switched to all-red (1936), Minneapolis-Moline switched to Prairie Gold (late 1930s), and Case switched to Flambeau Red (late 1930s). John Deere already had a distinctive color scheme with its bright green and yellow. Around 1929 to 1930, the United tractor became the Allis-Chalmers Model U when the United conglomerate collapsed due to disagreements between its investors. The 1930s were a pivotal decade. Despite the Great Depression, Allis-Chalmers succeeded as demand for its machinery continued. In 1931, it acquired Advance-Rumely of La Porte, Indiana, mostly because Merritt wanted the company's network of 24 branch houses and about 2,500 dealers, which would greatly increase Allis-Chalmers's marketing and sales power in the farm equipment business. Also in 1931, the corporation's electrical equipment business expanded via acquisition when Brown, Boveri & Cie, in a financial pinch because of the Depression, sold its U.S. electrical operations to Allis-Chalmers. After 1931 Allis-Chalmers was the licensee for U.S. sales of European products of Brown, Boveri & Cie. In 1932, Allis-Chalmers collaborated with Firestone to introduce pneumatic rubber tires to tractors. The innovation quickly spread industry-wide, as (to many farmers' surprise) it improved tractive force and fuel economy in the range of 10% to 20%. Within only 5 years, pneumatic rubber tires had displaced cleated steel wheels across roughly half of all tractors sold industry-wide. Cleated steel remained optional equipment into the 1940s. Also in 1932, Allis-Chalmers acquired the Ryan Manufacturing Company, which added various grader models to its construction equipment line. In 1933, Allis-Chalmers introduced its Model WC, its first-generation row-crop tractor, which would become its highest-selling tractor ever. In 1937, its lighter and more affordable second-generation row-crop, the Model B, arrived, and also became a top seller. Its All-Crop Harvester was the market leader in pull-type (tractor-drawn) combine harvesters. In October 1937, Allis-Chalmers was one of fourteen major electrical manufacturing companies that went to court to change the way labor unions excluded contractors and products in the building trades through the union use of the "Men and Means Clause". The action of Allis-Chalmers and others eventually resulted in the U.S. Supreme Court decision of June 18, 1945, that ended certain union practices that violated the Sherman Antitrust Act. World War II caused Allis-Chalmers, like most other manufacturing companies, to become extremely busy. As happened with many firms, its civilian product lines experienced a period of being "on hold", with emphasis on parts and service to keep existing machines running, but its war materiel production was pushed to the maximum of productivity and output. In the late 1930s through mid-1940s, Allis-Chalmers made machinery for naval ships, such as steam turbines, generators, and electric motors; artillery tractors and tractors for other army use; electrical switches and controls; and other products. Allis-Chalmers was also one of many firms contracted to build equipment for the Manhattan Project. Its experience in mining and milling machinery made it a logical choice for uranium mining and processing equipment. Allis-Chalmers ranked 45th among United States corporations in the value of wartime military production contracts. Immediately at the war's end, in 1945–1946, Allis-Chalmers endured a crippling 11-month labor strike. Buescher was convinced that the corporation never entirely recovered from the effects of this strike. This seems debatable given the various successes that Allis-Chalmers did have during the next 30 years, including prosperity in the farm equipment business in the 1950s and 1960s. But it certainly gave competitors a chance to grab market share. In 1948, the Model WC was improved with various new features and became the Model WD, another top seller. The 1950s were a time of great demand for more power in farm tractors, as well as greater capability from their hydraulic and electrical systems. It was also a decade of extensive dieselization, from railroad locomotives to farm tractors and construction equipment. In 1953, Allis-Chalmers acquired the Buda Engine Company of Harvey, Illinois. Allis wanted Buda for its line of diesel engines, because its previous supplier, Detroit Diesel, was a division of General Motors, whose recent acquisition of the Euclid heavy equipment company now made it a competitor of Allis-Chalmers for construction equipment business. The Buda-Lanova models were re-christened the "Allis-Chalmers Diesel" engine line. Diesel engineers were busy in follow years updating and expanding the line. In 1952, the company acquired Laplant-Choate, which added various models of scrapers to its construction equipment line. In 1955, the company acquired Gleaner Manufacturing Company, which was an important move for its combine harvester business. Allis was the market leader in pull-type (tractor-drawn) combines, with its All-Crop Harvester line. But acquiring Gleaner meant that it would now also be a leader in self-propelled machines, and it would own two of the leading brands in combines. The Gleaner line augmented (and later superseded) the All-Crop Harvester line, and for several years Gleaner's profits made up nearly all of Allis-Chalmers' profit. Gleaners continued to be manufactured at the same factory, in Independence, Missouri, after the acquisition. In 1957, the Allis-Chalmers D Series of tractors was introduced. It enjoyed great success over the next decade. In 1959, Allis-Chalmers acquired the French company Vendeuvre. Also in 1959, it acquired Tractomotive Corporation of Deerfield, Illinois, which it had been partnering with as an auxiliary equipment supplier for at least a decade. In Haycraft's history of the construction equipment business (2000), he expressed the view that Allis-Chalmers relied too heavily for too long on partnering with auxiliary equipment suppliers, and acquiring them, instead of investing in in-house product development. In his view, this strategy limited the company's success in this business, and it eventually had to spend the development dollars anyway. Buescher's comments about the Buda acquisition and the need for subsequent improvement of its designs seem to corroborate this view. However, the topic is multivariate and complex; elsewhere in his memoir, Buescher presents a viewpoint in which investing in research and product development is an expensive move that often doesn't pay off for the innovator and mostly benefits competitor clones. In 1960, the U.S. government uncovered an attempt to form a cartel in the heavy electric equipment industry. It charged 13 companies, including the largest in the industry (Westinghouse, General Electric, and Allis-Chalmers), with price fixing and bid rigging. Most feigned innocence, but Allis-Chalmers pleaded guilty. Although the public usually assumes that such cartels are created so that amply profitable firms can try to become obscenely profitable, Buescher's view of the attempt at a heavy-electrical cartel was that it was a desperate (and foolish) attempt to turn red ink to black ink among fierce competition. In 1965, Allis-Chalmers acquired Simplicity for its line of lawn and garden equipment. In the 1960s, the farm equipment, construction equipment, and heavy electrical industries were not as profitable for Allis-Chalmers as they had been in the 1930s through 1950s. Reasonable prosperity continued in the farm equipment line, but the economics of all the industries shifted toward greater uncertainty and brittler success for firms that didn't become number one or two in a field. Allis-Chalmers was often number three or four, as Deere and International Harvester led in farm machinery, Caterpillar and Case led in construction, and Westinghouse and General Electric led in heavy electric markets. In the late 1960s, a trend of conglomeration flared, as mega-conglomerates like Ling-Temco-Vought, Gulf+Western, and White Consolidated Industries went on buying sprees. Several takeover attempts by those firms were made on Allis-Chalmers. It was during the same era and business climate that Tenneco acquired Case. In 1974, Allis-Chalmers's construction equipment business was reorganized into a joint venture with Fiat SpA, which bought a 65% majority stake at the outset. The new company was called Fiat-Allis. In 1977, to compete with Kubota in compact diesel tractors, Allis-Chalmers began importing Hinomoto tractors with Toyosha diesel engines from Japan. They were rebadged with the Allis-Chalmers brand for U.S. sales. In 1978, a joint venture with Siemens, Siemens-Allis, was formed, supplying electrical control equipment. The company began to struggle in the 1980s in a climate of rapid economic change. It was forced amid financial struggles to sell major business lines. In 1983, Allis-Chalmers sold Simplicity, the lawn and garden equipment division, to the division's management. 1985 was a year of great dissolution for Allis-Chalmers—the year when it folded in three of its main business lines: In 1988, Allis-Chalmers sold its American Air Filter filtration business (with 27 production facilities internationally and sales into 100+ countries) for approximately $225 million to SnyderGeneral Corporation of Dallas, a leading global air quality control firm. In 1990, Deutz-Allis was sold to its management and became Allis-Gleaner Corporation (AGCO). Tractors began selling under the AGCO-Allis name. In 1998, what remained of the Allis-Chalmers manufacturing businesses were divested, and in January 1999, the company officially closed its Milwaukee offices. The remaining service businesses became Allis-Chalmers Energy in Houston, Texas. In August, 2008, Briggs & Stratton announced that it would sell lawn tractors under the Allis-Chalmers brand name. Allis-Chalmers offered a complete line of agricultural machinery, from tillage and harvesting to tractors. In 1959, a team led by Harry Ihrig built a 15 kW fuel cell tractor for Allis-Chalmers which was demonstrated across the US at state fairs. This was the first fuel-cell-powered vehicle. Potassium hydroxide served as the electrolyte. The original AC fuel cell tractor is currently on display at the Smithsonian. The first model introduced in 1949. They called their baler the "Roto-Baler". It was the fore-runner to what we know today as a round baler. Unlike today's large round bales of 1000 or 2000 pounds, its bales were small, about 75 pounds. The Roto-Baler was built until sometime in the 1960s or 1970s. Allis Chalmers also built many small square baler models. While AGCO is now the parts manufacturer for most of the parts one would need to fix up their older Allis-Chalmers tractors, including water pumps to oil filters, and even rebuild kits and tractor manuals, aftermarket suppliers offer parts that AGCO does not. Allis Chalmers marketed and sold a full line of Industrial and Power House equipment including turbo generators and medium voltage switchgear. In the 1920s through the 1960s AC Power House and Industrial equipment was very much competitive with industry giants like General Electric and Westinghouse. As early as the 1920s AC was manufacturing multi MVA hydro-electric generators and turbines, many of which are still in service today (Louisville Gas & Electric Ohio Falls units 1-8, 8MW low head turbines and Kentucky Utilities Dix Dam units 1-3, 11MVA 300 RPM generators). Allis Chalmers manufactured several lines of medium voltage switchgear, such as the HF and MA lines. The HF line was a direct competitor with the General Electric "AM" Magneblast line of vertical-lift medium-voltage switchgear. The MA line was a direct competitor of the ITE "HK" line of horizontal-racking medium-voltage switchgear. Also, Allis-Chalmers produced a line of substation transformers, voltage regulators, and distribution transformers. Allis Chalmers, during the period 1930-1965 and beyond, manufactured and marketed an extensive line of ore crushing equipment for the worldwide mining industry In 1965, Allis-Chalmers built "Big Allis," or Ravenswood No. 3, the biggest generator in New York. It's located in Queens, and has a total output of 1000 MW. It is still operational today. In the late 1960s and early 1970s AC expanded into the lawn and out-door products equipment market. AC made a line of 6-wheeled Amphibious ATV's called the "Terra Tiger". In 1965, Allis-Chalmers built hydrogen fueled fuel cell golf carts. Allis-Chalmers Energy is a Houston-based multi-faceted oilfield services company. Allis-Chalmers provides services and equipment to oil and natural gas exploration and production companies, both domestically and internationally.

Agricultural machinery is machinery used in the operation of an agricultural area or farm.

With the coming of the Industrial Revolution and the development of more complicated machines, farming methods took a great leap forward. Instead of harvesting grain by hand with a sharp blade, wheeled machines cut a continuous swath. Instead of threshing the grain by beating it with sticks, threshing machines separated the seeds from the heads and stalks. The first tractors appeared in the late 19th century.


A semi-trailer truck is a large vehicle that consists of a towing engine, known as a tractor in the United States and truck in many other places, attached to one or more semi-trailers to carry freight. It is also known as a transport in Canada; prime mover in Australia; semi, tractor-trailer, big rig, or 18-wheeler in the United States; and articulated lorry, abbreviated artic, in Britain and Ireland.

A semi-trailer does not trail completely behind the towing vehicle, but is attached at a point that is just forward of the rear-most axle of the towing unit. This is done so that a large portion of the weight of the trailer is carried by the prime mover. This arrangement means that both tractor and semi-trailer will have a distinctly different design than a rigid truck and trailer.


Two-wheel tractor or walking tractor are generic terms understood in the USA and in parts of Europe to represent a single-axle tractor, which is a tractor with one axle, self-powered and self-propelled, which can pull and power various farm implements such as a trailer, cultivator or harrow, a plough, or various seeders and harvesters. The operator usually walks behind it or rides the implement being towed. Similar terms are mistakenly applied to the household rotary tiller or power tiller that may be wheeled and/or self-propelled but often is not. A further distinction is seen in the two-wheeled tractor's ability to operate disparate types of agricultural equipment, while rotary tillers are smaller and specialize in soil tillage. This article concerns two-wheeled tractors as distinguished from such tillers.

Research has identified a number of terms used to identify two-wheel tractors, including "iron-ox; walking tractor; Kubota; mechanical ox; ox-machine; power tiller; rotary hoe, rotary plough, rotary tiller; Rotavator, [and] tok-tok".

A boat trailer is a trailer designed to launch, retrieve, carry and sometimes store boats.

Commercial hydraulic boat trailers are used by marinas, boatyards, boat hauliers, boat dealers and boat builders. Generally this type of trailer is not used for storage of the boat.

Heavy equipment refers to heavy-duty vehicles, specially designed for executing construction tasks, most frequently ones involving earthwork operations. They are also known as, heavy machines, heavy trucks, construction equipment, engineering equipment, heavy vehicles, or heavy hydraulics. They usually comprise five equipment systems: implement, traction, structure, power train, control and information. Heavy equipment functions through the mechanical advantage of a simple machine, the ratio between input force applied and force exerted is multiplied. Currently most equipment use hydraulic drives as a primary source of motion.

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