There are typically three types of hydraulic pump constructions within mobile hydraulic applications. These include 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 may be the component of the hydraulic system that takes mechanical energy and converts it into fluid energy in the kind of oil flow. This mechanical energy can be taken from what is called the prime mover (a turning power) such as the power take-off or directly from the pickup truck 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 Hydraulic Pump china operate in one path of shaft rotation. On the other hand, a bi-rotational pump has the ability to operate in either path.