A semi-trailer refers to a vehicle equipped with at least two axles. Its characteristics include: at least one of the axles is capable of flexible steering; it connects to a towing vehicle via a drawbar that permits angular movement; furthermore, the drawbar is capable of vertical movement and is fixed to the trailer chassis, meaning it cannot bear any vertical load. There is also a specific type of semi-trailer characterized by the presence of a retractable support stand; this variant is also referred to as a drawbar trailer.
More specifically, a semi-trailer is defined as a trailer in which the axles are situated behind the vehicle's center of gravity, and which is equipped with a coupling device capable of transmitting horizontal or vertical forces to the towing vehicle. A salient feature of this type of trailer is that it possesses no independent motive power and requires traction from a towing vehicle in order to move. However, in the specific case of semi-trailers designed for transporting automobiles, their length is permitted to exceed 17 meters.
In summary, a semi-trailer is a vehicle that shares the load in conjunction with a towing vehicle and relies on that vehicle's traction for propulsion. The design of such vehicles fully leverages the arrangement of the axles and the functionality of the coupling mechanism to achieve enhanced cargo-carrying capacity and transportation efficiency. Nevertheless, when utilized for the transport of automobiles, the length restrictions applicable to semi-trailers are subject to a slight relaxation.
