Pump Torque Limiter Provides Horsepower Control

An optional torque limiter for 45-140 cc/rev model P1/PD series pumps has been introduced by Parker Hannifin, Marysville, Ohio to benefit customers who need automatic torque limiting for their mobile and industrial applications. This allows the use of smaller prime movers, resulting in more efficient use of fuel or electricity.

"The torque limiter adjusts flow in the circuit to keep the prime mover from stalling under heavy loads," said Peter Medins, marketing product manager, Parker Hannifin Corp., Hydraulic Pump Division. "A good analogy is downshifting a heavy truck that's climbing a long grade. The engine puts out the same horsepower, but the truck simply goes slower as the grade increases. The benefit in a hydraulic system is that you can reduce the maximum horsepower available and still handle the same load without stalling. This capability is very significant in the mobile and industrial applications our compact P1/PD pumps are designed for."

To accomplish this, the torque limiter control monitors both pressure and displacement as measured by the pump's hanger angle. It is a single spring unit that works with the compensator, a ventable pressure limiter or a load sensing or remote venting circuit.

As pressure rises, flow is reduced according to the zero adjustment spring rate of the torque limiter. When pressure has risen to its full value, the compensator assumes control. The torque limiter normally functions down to 20 percent of corner horsepower, but lower adjustments are possible at the expense of peak pressure.

For more information, visit www.parker.com.