Displacement is the amount of hydraulic fluid that is displaced per cycle by the hydraulic pump or motor. The displacement helps to calculate the volumetric efficiency of pumps and motors, which indicates how effectively the device converts mechanical input into hydraulic flow.
Fixed displacement: In fixed displacement pumps or motors, the amount of fluid displaced per cycle is constant. These devices deliver a consistent flow rate regardless of the system’s operating pressure.
Variable displacement: In variable displacement pumps or motors, the amount of fluid displaced per cycle can be adjusted. This allows for control over the flow rate and pressure, making the system more versatile.
Displacement is usually measured in cubic centimeters per revolution (cm³/rev) or (cc), or liters per revolution (L/rev).
For example, if a pump has a displacement of 10 cc, it means that for every revolution of the pump shaft, it moves 10 cubic centimeters of hydraulic fluid.