There are usually three types of hydraulic pump constructions found in mobile hydraulic applications. Included in these are gear, piston and vane; however, there are also clutch pumps, dump pumps and pumps for refuse vehicles such as dry valve pumps
The hydraulic pump is the element of the hydraulic system that takes mechanical energy and converts it into fluid energy in the type 
of oil flow. This mechanical energy is definitely taken from what is Hydraulic Pump china called the primary mover (a turning power) such as the power take-off or directly from the vehicle engine.
With each hydraulic pump, the pump will be of either a uni-rotational or bi-rotational design. As its name implies, a uni-rotational pump is made to operate in one direction of shaft rotation. On the other hand, a bi-rotational pump has the capacity to operate in either path.