The hydraulic orbital motor is the rotary counterpart of the hydraulic cylinder as a linear actuator. Broadly speaking, these motors use hydraulic fluid as part of closed hydraulic circuits in hydraulic machinery. disk valve and geroller in design allows for high torque values to be achieved at low speeds.
Conceptually, a hydraulic motor should be interchangeable with a hydraulic pump because it performs the opposite function – similar to the way a DC electric motor is theoretically interchangeable with a DC electrical generator. However, most hydraulic pumps cannot be used as hydraulic motors because they cannot be back-driven. Also, a hydraulic motor is usually designed for working pressure on both sides of it.