Question:

What is the kingpin on a semi truck?

Answer:

The trailer of a semi connects to the fifth wheel hitch via a downward-facing pin-called a king pin. The king pin locks into MORE?

More Info:


semi truck

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.

Land transport Trucks Transport
Road transport

Road transport (British English) or road transportation (American English) is the transport of passengers or goods on roads.


Fifth wheel coupling

The fifth wheel coupling provides the link between a semi-trailer and the towing truck, tractor unit, leading trailer or dolly. Some recreational vehicles use a fifth wheel configuration, requiring the coupling to be installed in the bed of a pickup truck as a towing vehicle. The coupling consists of a kingpin, a 2-or-3 1⁄2-inch (50.8 or 88.9 mm) diameter steel pin on the front of the semi-trailer, and a horseshoe-shaped coupling device called a fifth wheel on the rear of the towing vehicle. The surface of the semi-trailer (with the kingpin at the center) rotates against the surface of the fixed fifth wheel, which does not rotate. To reduce friction, grease is applied to the surface of the fifth wheel. The configuration is sometimes called a turn-table in Australia and New Zealand, especially if it is a rotating ball-race-bearing type.

The term 'fifth wheel' comes from a similar coupling used on four-wheel horse-drawn carriages and wagons. The device allowed the front axle assembly to pivot in the horizontal plane, to facilitate turning. Basically a wheel was placed on the rear frame section of the truck, which back then only had four wheels, this wheel that was placed on the frame was the "fifth wheel" hence the name. The trailer needed to be raised so that the trailer's pin would be able to drop into the central hole of the fifth wheel. Today's fifth wheels allow the trailers to slide into the fifth wheel and lock into it, and are a very reliable unit when maintained and serviced properly. The engagement of the king pin into the fifth wheel locking mechanism is the only means of connection between tractor and trailer, no other device or safety mechanism is used. Couplers and pintle hooks will use safety chains in the event of a trailer separation while going down the road. Trailer-to-trailer connection can also be made by using fifth wheels.

Kingpin
Semi-trailer truck

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.

Trailer Lock Semi-trailer
Tow hitch

A tow hitch (or tow bar) is a device attached to the chassis of a vehicle for towing or a towbar to an aircraft nose gear, or paired main gears. It can take the form of a tow ball to allow swiveling and articulation of a trailer, or a tow pin and jaw with a trailer loop—often used for large or agricultural vehicles where slack in the pivot pin allows similar movements. Another category is the towing pintle used on military vehicles worldwide.


Human Interest

In journalism, a human interest story is a feature story that discusses a person or people in an emotional way. It presents people and their problems, concerns, or achievements in a way that brings about interest, sympathy or motivation in the reader or viewer.

Human interest stories may be "the story behind the story" about an event, organization, or otherwise faceless historical happening, such as about the life of an individual soldier during wartime, an interview with a survivor of a natural disaster, a random act of kindness or profile of someone known for a career achievement.

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