When high operating pressures are required, piston pumps tend to be used. Piston pumps will typically endure higher pressures than gear pumps with comparable displacements; however, there is a higher initial cost associated with piston pumps in addition to a lower resistance to contamination and increased complexity. This complexity falls to the gear designer and service technician to understand in order to make sure the piston pump is working correctly with its additional shifting parts, stricter filtration requirements and closer tolerances. Piston pumps are often used in combination with truck-installed cranes, but are also found within other applications such as snow and ice control where it might be desirable to vary system flow without varying engine rate.
A cylinder prevent containing pistons that move in and 
out is housed within a piston pump. It’s the movement of these pistons that draw oil from the supply slot and then power it through the wall plug. The angle of the swash plate, that your slipper end of the piston rides against, determines the space of the piston’s stroke. As the swash plate remains stationary, the cylinder prevent, encompassing the pistons, rotates with the pump’s input shaft. The pump displacement is usually then determined by the total volume of the pump’s cylinders. Fixed and variable displacement designs are both available.