Fixed displacement motors and pumps cannot be regulated. The displacement (flow rate) is determined by the angle of the reaction plate support and the drive speed. They are normally set for maximum displacement, but can be supplied on special order set for reduced displacement.

The output torque of a fluid motor is a function of the pressure and displacement. Generally they should be used where the torque requirements are fairly constant throughout the speed range of aparticular application. Under all operating conditions the oil pressure at either port must not fall below atmospheric pressure,

Motor drive shaft rotation is bi-directional (oil flow can be reversed—see chart).

Unlike motors, the pump drive shaft rotation Is unidirectional (oil flows in one direction only—see chart). A pressure relief valve must be incorporated into the circuit for both pumps and motors.