semi trailer assembly 3D model

A large proportion of a semi-trailer's weight is supported by a tractor unit, or a detachable front-axle assembly known as a dolly, or the tail of another trailer. The semi-trailer's weight is semi-supported (half-supported) by its own wheels, at the rear of the semi-trailer. A semi-trailer is normally equipped with landing gear (legs which can be lowered) to support it when it is uncoupled. Semi-trailers are more popular for transport than full trailers, which have both front and rear axles. Ease of backing is cited as one of the semi's chief advantages