Pneumatic Rack and Pinion Actuators

Rack and Pinion actuators are available for a wide range of advanced applications. Most well know are the temperature related trim kits that allow High Temperature or Low Temperature operation.

Other applications are related to manipulating the stroke differently (Full Stroke Adjustment), special coating requirements, special operating media, or fast operating speeds.

For many of these advanced applications, dedicated control accessories are available.

Rack and Pinion actuators have standardized interface flanges/interfaces for valves, solenoids and control accessories.

Valve interfaces generally comply to the ISO 5211 standard. This torque-based standard has become the industry standard and many valves are available that allow direct mounting, eliminating cost for bracket and coupling. For valves that do not allow direct mounting, many standardized brackets are available to reduce cost to a minimum.

Between the actuator and the valve, a Declutchable Manual Override Gear Box can be mounted that allows manual operation of the automated valve package in case of emergencies or when maintenance of the actuator is required.

Solenoid and control accessory interfaces comply to the VDI/VDE 3845 (NAMUR) standard and European actuator standard EN15714-3. The solenoid interface allows either piped or direct-mounted solenoids and allows various pneumatic interface sizes based on actuator volume to accommodate cycle speed requirements.

The control accessory interface, on top of the actuator, allows the mounting of switch boxes or analog position transmitters. These devices are mounted to the actuator's pinion, which is mounted direct or indirect to the valve’s stem and allows position feedback of the automated valve package to the control room. Switch boxes in general sense the fully open and closed end positions where the analog position transmitters indicate the actual position throughout the stroke by means of a 4-20mA or 0-10V signal. For modulating applications, valve positioners are available to mount directly to the actuator top.

Many suppliers offer various control components per the VDI/VDE 3845 (NAMUR) standard. However, the many different components must be ordered, stocked, handled, mounted, etc.

Many customers look now for a more integrated valve operating system that reduces the variety of components and the number of potential malfunction points. Some switch box suppliers now provide semi-integrated solutions where the switchbox is equipped with a solenoid. One of the latest developments is integrating the control and the position feedback in one control module which fits on the full range of actuator sizes.