Advantages of Rotary Pneumatic Actuators Over Rack & Pinion and Scotch Yoke Actuators

Rotary actuator control valve.
(Easytork)

By virtue of their design, pure rotary-to-rotary actuators experience zero repeatability loss, regardless of how long the actuator is used, making them a better choice than linear-to-rotary actuators.

The Problem

Rack and pinion or scotch-yoke actuators on the market today convert linear to rotary movement. The wear between the racks and pinion will worsen over time, increasing the repeatability losses. Rack and pinion, and diaphragm actuators, all require gears to convert linear motion to rotary motion, adding rack and gearing tolerances which add backlash or hysteresis. Over time, wear in the rack and gearing areas add additional backlash or hysteresis, degrading the actuators repeatability.

The Solution

Pneumatic vane actuators are pure rotary-to-rotary, meaning all motion produced by the vane actuator transfers unfiltered to the valve stem with zero motion loss. Unlike linear-to-rotary actuators, where the pinion experiences wear and lost motion which leads to increased backlash over time, rotary-to-rotary designs do not have to contend with the increased backlash.

For more information, contact:
Process Control Solutions
https://flowcontrol.processcontrolsolutions.com
(800) 462-5769