When high operating pressures are required, piston pumps are often used. Piston pumps will typically endure higher pressures than gear pumps with comparable displacements; however, there is a higher initial price associated with piston pumps in addition to a lower level of resistance to contamination and improved complexity. This complexity falls to the equipment designer and service technician to understand to be able to make certain the piston pump can be working correctly with its additional moving parts, stricter filtration requirements and closer tolerances. Piston pumps are often used 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 block containing pistons that move in and out is housed within a piston pump. It’s the movement of the pistons that draw oil from the supply slot and then power it through the outlet. The angle of the swash plate, which the slipper end of the piston rides against, determines the length of the piston’s stroke. While the swash plate remains stationary, the cylinder prevent, encompassing the pistons, rotates with the pump’s input shaft. The pump displacement is usually then dependant on the total level of the pump’s cylinders. Fixed and variable displacement designs are both available.