A trailer is a means of transport set into motion by another motor vehicle, for example, a tractor unit, a standard tractor or a truck. Trailers with hydraulic power drive and mechanical drive on one or several axles exist. As contrasted with semitrailers, the GVW of trailers is totally disposed on the wheels through the truck frame. A trailer is attached to a truck or tractor unit with the help of a tow-bar and a draw-bar (for instance, “loop & hook” system).

A trailer, as well as a semitrailer, can be divided into two components: a flatbed platform and an automotive platform. An automotive part consists of chassis or a truck frame and one, two or several axles.

A flatbed platform is introduced in various modifications depending on the intended purpose: there are drop-side trailers, dump trailers, bolster trailers, tank trailers, trailer wagons, heavy-duty trailers, light-duty trailers and special trailers.

Open and shut load-carrying platforms exist. Open platforms can be drop-sided, with chassis, dumpers and special platforms for machinery transportation. Such trailers are made of impact resistant and long-wearing materials, such as steel or hardwood. Low-bed platforms should be exceptionally robust. These platforms are intended for heavy and bulky load transportation, for example excavators and earthmoving machines. Shut platforms consist of a skeleton frame, made of steel, wood or plastic. It’s covered with canvas cover, steel and PVC sheets to provide load protection. To enhance the isothermal effect, special non-conducting and thermal-resistant materials, as well as “sandwich-panels”, are used. Besides, trailers are equipped with refrigerating engineering and are transformed into refrigerators. Fixation appliances can be fitted into shut platforms (for example, anchor tires or rings), as well as loading/unloading devices and inner frames for multistage load disposition. Liquid storage tanks and special containers for fuel, hazardous liquids (such as ammonia) and drinks transportation can also be installed on the platform. Beyond that, trailers can be transformed into residential homes and laboratories, fitted with heating system, water supply system, current flow power converters, ventilating system, etc.

The same company produces both trailers and semitrailers. The product is often being developed and assembled with the use of the complements manufactured by the companies, which specialize in chassis, suspenders and non-conducting materials. Some companies develop chassis by themselves (such as Kögel and Schmitz).

Some components of trailers (chassis, suspenders and draw-bars) are standardized to provide safety performance and the convenience of certification procedure. Schmitz Cargobull, Kögel and Krone are the European trailer producing market leaders.