Hydraulic Motor/Hydromotor

Hydraulic motors are very similar to hydraulic pumps. However, in many cases, a separate drain oil line is essential! The motor's rotational speed is determined by the oil flow, while the generated torque is governed by the system's pressure. For applications requiring high torque but low speed, orbit motors are the ideal solution.

Our experts are ready to assist in synchronizing hydraulic pumps and motors. Motor control should be managed with the appropriate hydraulic valves.

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Hydraulic Motors / Hydromotors

Hydraulic motors are very similar to hydraulic pumps. Based on design, like pumps, there are piston, vane, and gear hydraulic motors, but what is unique to motors is the orbit system. Motors are always single-circuit; multi-circuit systems are not applicable here. The rotator used in cranes is essentially a vane hydromotor. It is very important to note that while the internal drain oil in pumps can be returned to the suction side, in motors, this often needs to be connected separately to the reservoir with the least possible pressure loss—without a return line filter, directly into the hydraulic tank.

Motors generate rotational movement and transmit torque by converting hydraulic energy. Hydraulic energy is proportional to the product of system pressure (p) and flow rate (V). Rotational power (P) is proportional to torque (M) and angular velocity, i.e., RPM (n). The hydraulic motor delivers torque in proportion to the displacement volume, meaning larger hydromotors deliver greater torque. Torque can also be increased by raising pressure. Therefore, to achieve higher performance, you can either increase the physical size and RPM of the hydromotor by increasing the oil flow, or compensate for the size increase by raising pressure.

Orbit motors are specifically designed to generate high torque at relatively low speeds (200-300 RPM, but up to a maximum of 1000 RPM). They are used in conveyor belts, various material-handling pumps, vehicles, machinery, crane travel drives, winches, and many other applications. Orbit hydraulic motors operate at relatively low pressures (up to 200 bar).

Hydraulic Motor Control

The direction of rotation of hydraulic motors is never fixed; it is always determined by the direction of flow. In a hydraulic system, the motor can be controlled by a directional hydraulic control valve, which determines the direction of rotation. In certain cases, the rotational speed can be minimally adjusted with the appropriate proportional valve, but it is more effective to set the required rotational speed through central flow control, such as with a flow regulator. The control valve must be suitable for controlling hydraulic motors, with positive overlap between the A-T-B ports in the correct manner. Improper control can damage the motor!

Hydraulic Motor Installation

The motor drives the equipment through a coupling. The coupling must be sized according to technical and safety considerations, ensuring that in the event of equipment failure, it can disengage to protect the machinery from forced driving and avoid further damage. With hydraulic motors, it’s easier to manage because the maximum deliverable torque can be set using the appropriate pressure relief valve, allowing for different modes or directions to be controlled in different ways. When ordering hydromotors, the shaft and mounting flange must be specified. When connecting, do not forget to ensure the proper routing of the drain oil line. If the hydraulic system needs to connect via a quick connector, special attention must be paid. Connecting a pressure line to the drain oil port will definitely lead to failure!

Before sizing or purchasing a hydraulic motor, consult the experts at MPH Ltd. for advice!