Gerotor Motors – Compact Hydraulic Power with Smooth Rotation

Gerotor motors are compact hydraulic units designed for low-to-medium speed and medium-to-high torque output. Their name comes from “generated rotor,” referencing the unique internal geometry that drives their performance.

How Gerotor Motors Operate

A gerotor motor features a gear-within-gear design, consisting of:

• An inner rotor with N teeth
• An outer rotor with N + 1 teeth

The axis of the inner rotor is offset from the outer rotor, and both rotate on their own axes. This offset creates a series of dynamically changing volumes between the rotors. 

As the motor cycles, each chamber expands and contracts:

• Expansion creates a vacuum, drawing fluid into the motor
• Contraction compresses the fluid, generating torque and driving rotation

This positive displacement process ensures consistent output and smooth operation.

Design Characteristics and Performance

• Low-to-medium speed, medium-to-high torque
• Compact form factor for space-limited systems
• Smooth rotational motion with minimal vibration
• Positive displacement operation for reliable torque
• Simple internal geometry with gradual wear profile
• Cost-effective alternative to roller gerotor motors

Hydraulic Components from Leading Hydraulic Brands

We work with a portfolio of over 80 respected hydraulic manufacturers, including: Adan, Danfoss, Parker, Maxma and more – providing you with access to a broad selection of gerotor motors without brand bias. Whether you’re after a standard unit or something more specific, our team can help you compare options and source the right part for your system.

As official UK Export Champions, we have supported customers and professionals in more than 130 countries and spanning over 20 sectors including agriculture, marine, manufacturing, and construction – wherever reliable hydraulic power is needed.

Frequently Asked Questions

What is a gerotor motor used for? Gerotor motors are used in hydraulic systems that require compact size, smooth rotation, and consistent torque – in either mobile or industrial equipment.

How does a gerotor motor differ from a geroler motor? Gerotor motors use the stator wall to form displacement chambers, while geroler motors use roller pins for tighter tolerances and improved wear resistance.

Why does the rotor have N teeth and the stator N + 1? This tooth mismatch creates the necessary chamber movement for fluid displacement, enabling continuous rotation and torque generation.

Speak to a Hydraulic Specialist

Choosing the right motor doesn’t have to be complicated. Our technical team is here to help you assess your requirements, compare brands, and identify the most suitable solution – whether you’re replacing a unit or building a new system.

We supply:

Hydraulic Pumps | Hydraulic Valves  | Hydraulic Cylinders | Hydraulic Filters | Custom Hydraulic Power Packs  |  Hydraulic Motor Repair Service… alongside thousands of other Hydraulic Components and Accessories

Our website showcases just a selection of what we supply. For impartial advice and access to thousands more hydraulic components, contact our expert team – wherever you are.