Hydraulic motor refers to the liquid as the working medium, the use of liquid pressure energy to transfer power engine.

Engine is a machine that can convert other forms of energy into mechanical energy, including internal combustion engines (gasoline engines, etc.), external combustion engines (Stirling engines, steam engines, etc.), motors, etc. For example, internal combustion engines usually convert chemical energy into mechanical energy. The engine is suitable for both the power generator and the whole machine including the power plant (e. g. gasoline engine, aeroengine). Engine was first born in Britain, so the concept of engine also originated in English, its original meaning is that kind of “power generation machinery”.

A complete hydraulic system consists of five parts, namely, energy device, actuator, control and regulation device, auxiliary device, liquid medium. Hydraulic pressure is widely used in industry and civil industry because of its large transmission power, easy transmission and configuration. Actuators of hydraulic systems (hydraulic cylinders and hydraulic motors) are used to convert the pressure energy of the liquid into mechanical energy, thereby obtaining the desired linear reciprocating or rotary motion. The function of the energy device (hydraulic pump) of the hydraulic system is to convert the mechanical energy of the prime mover into the pressure energy of the liquid.