Semi=trailer forming rigid vehicle with tractor

摘要

The semi-trailer (2) has an oblong chassis with two or more couplings at the same side and spaced apart in the lengthwise direction. These secure it to the tractor vehicle (1) so that it cannot turn in the vertical or horizontal directions, and are clear of one or more supporting wheeled axles (8,10). A spring (9) regulates the load/suspension characteristic of the axle, and is controlled dependent on the load on one or more axles (4) of the tractor vehicle. The spring can be pneumatic, air being supplied or discharged under control of a data-processing unit dependent on the axle-load data received by the latter. The air-supply pipe can be connected to the pneumatic suspension system of the tractor vehicle clear of the semi-trailer axle.