A trend slowly creeping its way into industrial hydraulics is driving the system with a fixed-displacement pump at variable speed. In some cases, this type of hydraulic power unit (HPU) replaces a conventional one. But in the most high-tech cases, response is so precise that the HPU can drive actuators directly, eliminating the need for proportional and servovalves for a single axis.

To serve this trend, Zero-Max Inc., Plymouth, Minn. recently introduced CD shaft couplings, which are intended for use with fixed-displacement hydraulic pumps driven by electric servomotors. CD Couplings combine high dynamic load capacity with high torsional stiffness to ensure reliable system operation.

“This new pump drive technology has become increasingly popular because of dramatic improvements in energy efficiency and noise reduction”, reports Robert Mainz, of Zero-Max. “These pump systems utilize the power and precision that only a servomotor can provide. The system pressure is controlled by modulating the output volume of a fixed-displacement pump. This is made possible by a high-performance control system and the (motorto- shaft) coupling.”

CD couplings are constructed with a working element made of a composite material. The composite disc design withstands the rapid speed, torque, and even directional changes required of servomotors for these applications. Existing users report that couplings enable the systems to perform well not only in test lab environments, but more importantly, on the production floor.

CD couplings are available in single and double flex aluminum hub models with or without keyways. The single flex models come in sizes with maximum torque ratings from 40 to 1436 N-m and higher, with speed ratings from 4400 to 17,000 rpm.

For more information, call (763) 546- 4300 zero-max@zero-max.com or visit www.zero-max.com.