The world of hydraulic motors is vast with numerous motor types available for various applications. To qualify as a hydraulic motor, a motor must utilize incompressible fluid to convert hydraulic pressure into torque and rotation. In applications that require low speeds (generally less than 1000 rpm) and high torques, an orbital-style, gerotor motor stands above the rest.
What is an orbital motor?
An orbital-style motor consists of several roller vanes positioned in pockets around the inside diameter of a stator, that act as a guide for an internal rotor to orbit. The rotor’s rotation is achieved through a pressure differential created by fluid flow. Constantly shifting high- and low-pressure zones are created, resulting in a smooth and consistent rotation. Once the fluid has moved through the motor, the fluid can be returned to a holding tank, or directly to the pump itself. The rotor drives an output shaft, which is connected via a “dogbone”-style drive link. This output shaft is connected to whatever is being driven (a wheel, auger, conveyor, etc.), and high torque can be applied. This direct connection creates a smooth transfer of the required speed and torque for an application.
What about a case drain?
There are two, smaller groups of low-speed, high-torque orbital motors, two-zone and three-zone. The primary difference between a two-zone and three-zone motor is the inclusion of a case-drain. A three-zone motor uses a case drain as a secondary outlet, where fluid can be returned to a tank (or pump) if the application’s pressure becomes too high. Alleviating this pressure aids cooling and can extend motor seal life. Additionally, the case drain line can drain excess internal oil leakage. This design feature allows three-zone motors to be linked in series for higher-pressure applications while maintaining the flow levels of a two-zone torqmotor. In the case of a two-zone motor, the absence of a case drain means that extra adapters and hoses are not needed to connect a secondary outlet, making the entire system more cost-effective. Two-zone motors can be equipped with high-pressure shaft seals to bolster capability, but can not perform in the same, high-pressure environments as a three-zone motor.
Parker Quality in a Three-Zone Package
Parker’s 3Z Series is the latest addition to the Parker Pump & Motor Division’s product portfolio. The 3Z line consists of two, three-zone, orbital-style motors. The orbital-style design reduces friction to a minimum, and increases the efficiency of the overall design, even at high pressures. The 3ZE and 3ZG models can provide up to 24GPM and 40GPM of flow, respectively, making the series ideal for applications across numerous markets. Find out more at www.discover.parker.com/3ZSeries.
The Pump & Motor Division is a market leader in gear pump and low speed-high torque gerotor motors, that continues to blaze a trail in the industry by developing new technologies while maintaining the high level of service synonymous with Parker. Between its two locations in North Carolina and Tennessee, the division employs decades of industry experience to better serve you and your application.
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Article contributed by C.T. Lefler, market product manager, Parker Hannifin's Pump & Motor Division.