There are usually three types of hydraulic pump constructions found in mobile hydraulic applications. Included in these are gear, piston and vane; nevertheless, additionally, there are 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 type of oil flow. This mechanical energy can be taken from what’s called the prime mover (a turning push) such as the power take-off or directly from the pickup truck engine.
With each hydraulic pump, the pump will be of the Hydraulic Pump china uni-rotational or bi-rotational design. As its name implies, a uni-rotational pump is made to operate in one path of shaft rotation. However, a bi-rotational pump has the ability to operate in either path.