In pneumatic valve actuators, fretting wear is caused by the repeated cyclical rubbing between gears in scotch yoke or rack and pinion actuators. Over a period of time, fretting will remove material from one or both surfaces. This extra material, or debris, is usually harder than its source material due to work hardening and oxidation. The resulting debris becomes an even more effective abrasive, increasing the rate of mechanical wear and continued fretting.
Backlash happens when gears change direction. It is caused by the gap between the trailing face of the driving tooth and the leading face of the tooth behind it. Both fretting and backlash significantly affect the service life of a pneumatic valve or damper actuator.
Kinetrol’s rotary vane actuator uses a single piece of machined steel for both the vane body and drive shafts. With this design, the shaft and vane are not affected by backlash, friction or wear. Vane actuators incorporate a design with only a single moving part that provides very repeatable, smooth movement that will not decay over time.
