Different from the full trailer, semi-trailer axles is at the vehicle centre of gravity (when the vehicle even when loaded), and can be horizontal or vertical transmission to the towing coupling devices for trailers! General trailer two axle, trailer a shaft. Semi, refers to itself without power, with the main shared hosting relies on primarycar traction vehicles.
Simply put, full trailers and trucks in front of hook connection. Semi-trailer is connected by a PIN with tractor traction, common is a typical semi-trailer container transport car, is the semi-trailer loading section later.
Purposes may differ, all trailers are mainly used for factories, ports, docks, warehouses and transport over short distances within the field, and semi trailers used cargo transportation.