Overview of Eaton Char-Lynn Hydraulic Motors
Char-Lynn is the world’s leading hydraulic motor brand, renowned for offering the broadest range of orbital motors designed for heavy-duty industrial applications. Previously part of the Eaton corporation, the Char-Lynn brand has since been transferred to Danfoss — Denmark’s leading group in hydraulic engineering and motion control.
With over half a century of development, Eaton Char-Lynn hydraulic motors are widely used in agriculture, construction, mining, marine, and many other industries thanks to their low-speed, high-torque (LSHT) characteristics, outstanding durability, and compact design.
Operating Principle — The Orbit Principle
All Char-Lynn motors operate on the Orbit Principle. The core mechanism consists of a specialized gear pair:
- Gerotor/Geroler: The inner gear (rotor) orbits inside a fixed outer gear (stator). The difference in tooth count between the rotor and stator creates sealed chambers that continuously change in volume as the rotor turns.
- Energy conversion: High-pressure hydraulic fluid enters the expanding chambers, driving the rotor and generating torque at the output shaft. Low-pressure fluid is then discharged from the contracting chambers.
- Bi-directional operation: The motor is fully reversible (bi-directional) — simply reverse the supply flow to change the direction of rotation.
This design enables Char-Lynn motors to deliver high energy efficiency, smooth operation, and long service life even under heavy-load conditions.
Three Main Valve Distribution Types
Char-Lynn motors use three different oil distribution valve technologies, each suited to specific application requirements:
1. Spool Valve
Uses a sliding piston to direct oil flow. This straightforward, cost-effective design is well suited for applications requiring moderate torque and medium speed. Representative series: H Series and S Series.
2. Disc Valve
Uses a flat rotating disc to distribute oil, reducing internal leakage and improving volumetric efficiency. This allows higher working pressures and greater torque output compared to spool valve designs. The three-zone construction significantly extends service life. Representative series: 2000 Series, 4000 Series, 6000 Series, 10000 Series.
3. VIS — Valve-In-Star
The most advanced technology, integrating the distribution valve directly into the stator assembly. This minimizes pressure losses, delivers the highest efficiency of the three types, and withstands working pressures well above those of disc valve designs. Representative series: VIS40 and VIS45.
Main Product Lines & Technical Specifications
The table below summarizes the most popular Char-Lynn motor series along with their key specifications:
| Product Series | Displacement | Continuous Pressure | Max Torque | Max Flow Rate | Valve Type |
|---|---|---|---|---|---|
| H Series | 36–739 cc/rev (13 sizes) | — | — | 57 L/min (15 GPM) | Spool Valve |
| S Series | Various | — | — | — | Spool Valve |
| 2000 Series | 34–490 cc (13 sizes) | 205 bar (3,000 PSI) | 845 Nm | 75 L/min | Disc Valve |
| 4000 Series | 110–625 cm³/rev (9 sizes) | 115–205 bar | 970 Nm | 75–95 L/min | Disc Valve |
| 6000 Series | 195–985 cm³/rev (9 sizes) | — | 1,685 Nm | 150 L/min | Disc Valve |
| 10000 Series | Large | — | Very high | — | Disc Valve |