When high operating pressures are required, piston pumps tend to be used. Piston pumps will traditionally endure higher pressures than gear pumps with similar displacements; however, there exists a higher initial price associated with piston pumps in addition to a lower resistance to contamination and improved complexity. This complexity falls to the equipment designer and service technician to understand in order to make sure the piston pump can be working correctly using its additional moving 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 could be desirable to vary system circulation without varying engine rate.

A cylinder block containing pistons that move around in and out is housed within a piston pump. It’s the movement of these pistons that draw oil from the supply port and then push it through the wall plug. The position of the swash plate, which the slipper end of the piston rides against, determines the distance of the piston’s stroke. As the swash plate continues to be stationary, the cylinder block, encompassing the pistons, rotates with the pump’s input shaft. The pump displacement is certainly then determined by the total level of the pump’s cylinders. Fixed and variable displacement styles are both available.