At the heart of the Rineer Hydraulics, Inc.® motor is a patented vane-crossing-vane design, a unique idea in fluid power transmission. This design allows for low speed high torque and high speed high torque making it one of the most versatile motors in the industry.
The Rineer motor is a bi-rotational rotary power converter utilizing working vanes in the rotating member (rotor, see Fig. 1), and sealing vanes in the stationary member (stator). These vanes are hydraulically and spring loaded, and are radiused on their crossing edges. The rotor vanes, when acted upon by a differential pressure, exert rotational force on the rotor. As oil enters the "A" ports, the rotor vanes rotate clock-wise toward the "B" ports. As each rotor vane is finishing its work cycle in a cavity, another rotor vane starts its work cycle in that cavity.
There are four rotor vanes working at any given time. For example, as the two vanes marked "C" have just started their work cycle and are continuing to "cam out," the two vanes marked "D" are just past the mid-point of their work cycle and are "camming back". This results in approximate constant vane extension and, therefore, the output approaches constant torque regardless of radial location. Each rotor vane works once per cavity per revolution resulting in 40 power strokes in a four cavity (10 rotor vane) motor.

As the rotor vanes approach the stator vanes, the radius of the vanes tips come into contact, thus allowing each vane to ride past the other. Both rotor and stator vanes have the same pressure behind them. The wider rotor vane, having greater hydraulic and spring force, pushes the thinner stator vane back into its slot and because the rotor vane is wider than the stator vane slot, it will not enter the stator vane slot.

The stator vanes function as high-pressure to low-pressure seals between inlet and outlet ports. This enables the incorporation of more working cavities in less area, thus improving both the mechanical and volumetric efficiencies.


New versions of the Series 37, 57, and 125 motors, called "PC", have been introduced to replace the original design. With this recently patented feature, the timing plates are hydraulically balanced with approximately equal force towards the rotor to better control crossport and case leakage.

PC motors operate with increased efficiency over the entire performance range relative to the original design. They retain the excellent low-speed torque efficiency of the original, but have improved overall efficiency.

Stall and Starting Torque

The torque curves are virtually flat with starting and stall torque equal to 90 to 94 percent of theoretical torque.

More Power Strokes Per Revolution

The 15, 37, and 57 Series have four stator cavities and 10 rotor vanes while the 125 Series has six stator cavities and 16 rotor vanes. Since each rotor vane works in each stator cavity once per revolution, the 15, 37, and 57 Series have 40 power strokes per revolution; the 125 Series has 96 power strokes per revolution.

Smaller and Lighter Than Typical Motors

The Rineer design results in a smaller and lighter envelope package for a given displacement. For example, a 15 cubic inch motor weighs only 43 pounds and the 125 cubic inch motor weighs only 225 pounds.

Smooth Output Over a Wide Speed Range

The increased number of power strokes per revolution, plus the flat torque curve, generates a smooth operation from less than 10 rpm to 2000 rpm and beyond, depending on the series.

The introduction of the stator vanes, plus the overall smaller package size, improves the volumetric efficiency. More working rotor vanes, coupled with the breakaway pressure of 18 p.s.i., improves the mechanical efficiency of the motor. Resulting OVERALL efficiencies in excess of 92 percent can be reached.
Shaft and Bearing Options

Besides the standard keyed and splined shaft motors, Rineer has designed many unique shaft and bearing arrangements to accommodate high thrust or radial loads, media transmission through the shaft, and special mounts for OEM concerns.

Tandem Motors

Rineer has developed a "two motors on one shaft" concept which allows for two complete motors to be built using one shaft output. This allows 2 motors of the same or different series to be close coupled. By using external valving, one or the other can be individually loaded or unloaded for high torque, or high speed modes.

4-Ported Motors Available

Rineer has developed a 4-ported motor in the 37, 57, and 125 series consisting of two packages separated by a special center housing effectively creating two separate motors on one shaft. This configuration allows the flexibility to create a motor with the front package of one displacement, the rear package of a different displacement, or both packages of the same displacement. Given these selections, a single motor can operate as a two-speed motor with different shift ratios, with some external valving.

Two Speed Motors Available

The 15 series is available in a two speed version. The rear housing incorporates a spool valve which shifts between full displacement and partial or half displacement. The motor can be shifted on the run.