The force switch is the force device, is a group or more groups of variable speed gear, also known as the power output device, generally by the combination of gear box, clutch, controller, and gearbox low-end gear or auxiliary box output shaft connection, the power output to the external working device, such as lifting pump.
According to the different control modes, there are mechanical control, hydraulic control, air control, vacuum source control, electric control and other control modes, among which the air control is more common.
According to the different forms of power output, it can usually be divided into transmission side power output form, transmission front power output form, transmission back power output form, engine front power output form.