Trailer

are non-powered vehicles that are pulled by a towing vehicle (truck, tractor, etc.). Power is transmitted via the drawbar, which is either rigid or designed as a steered front axle of the trailer. Rail-guided A. are referred to as wagons or lorries (A. with a trough for transporting bulk goods). A. without a front axle that rest on the towing vehicle (tractor unit) are referred to as semi-trailers. Cf. tractor, swap body.

Source: logipedia / Fraunhofer IML