Hydraulic machines use the power of fluid fluid to do the job. Heavy construction vehicles are a common example. In this type of machine, hydraulic fluid is pumped throughout the machine to various hydraulic motors and hydraulic cylinders and pressurized according to the available resistance.

Fluid is controlled directly or automatically by control valves and is distributed through hoses, pipes and / or pipes.

Hydraulic systems such as pneumatic systems are based on Pascal's law, which states that any pressure applied to a fluid in a closed system will transmit that pressure equally to all places and in all directions.

A hydraulic system uses an incompressible fluid as a fluid rather than a compressible gas.

The popularity of hydraulic machines is due to the enormous amount of power that can be transmitted through small tubes and flexible hoses, and the high power density and wide range of actuators that can use this power and the enormous power increase. It can be achieved by applying pressure to relatively large areas.

A disadvantage compared to machines using gears and shafts is that any power transmission causes some losses due to the resistance of the fluid flow in the pipes.