A tractor unit is the towing unit of a semi-trailer truck

What is a tractor unit?

A tractor unit is the towing unit of an articulated truck. While an articulated train consists of a motor vehicle (with its own loading area) and a trailer, a semitrailer tractor consists of a semitrailer tractor and a semitrailer. Another term for tractor unit is articulated lorry.

The tractor unit consists of a short truck chassis with a driver’s cab and does not have its own loading area. It is therefore significantly shorter than a truck. Instead, the tractor unit has a fifth wheel coupling to accommodate the semi-trailer.

The fifth wheel connects the tractor unit and trailer, which has a kingpin for this purpose. The fifth wheel coupling consists of a plate with an integrated locking mechanism. The semi-trailer rests on this locking mechanism. The kingpin is the pivotal point of the semi-trailer combination. It allows both vehicles to move but is securely connected to each other.

What types of semi-trailers are there?

Semi-trailer tractors can tow all types of semi-trailers. Tarpaulin semi-trailers (tautliners/ curtainsiders) are the most common. However, there are also box trailers, refrigerated trailers and tipper body trailers.