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