The transmission system refers to the collective term for all power transmission devicesbetween the engine and the driving wheels. Different cars have slightly different chassis compositions: for example, for trucks and somesedans, the chassis is generally composed of clutches, manual transmissions, universaltransmission devices, drive axles, etc; Nowadays, more and more cars are using automatictransmissions, which include chassis components such as automatic transmissions, universatransmission devices, and drive axles, replacing clutches and manual transmissions withautomatic transmissions; lf it is an off-road vehicle (including SUV, i.e. sport utility vehicle).