Hydro-static transmission how it work

The hydro-static transmission transmits energy using hydraulic fluid. The usual transmission has two hydraulic devices; one working as a variable displacement pump and the other working as a motor connected by hydraulic lines. The pump converts mechanical energy into pressure and the motor reconverts the pressure energy to mechanical energy. By varying the displacement of the pump a continuous ratio from zero to the maximum value can be obtained thereby forming an infinitely variable transmission (IVT). As a result the hydro static transmission does not require any starting clutch. The torque direction is reversed by the pump acting as the motor and the motor acting as the pump. The hydro static transmissions are simple to construct and offer flexibility; however, they are bulky and noisy, so they tend to be used more in heavy vehicles than in passenger cars.