UniTorq can provide a special setup allowing for a mid position setting on any double acting pneumatic actuator. This setup will work for both 90 degree thru 180 degree actuators. The mid position setting is adjustable to any point between the actuator's ends of travel. The set-up will fail in last place only, if it is desirable to fail in the mid position we offer our 90X90 pneumatic series actuator.
To accomplish this a Com7 switchbox with 2 mechanical SPDT switches and a 3 position, dual coil 5 way solenoid is required. The solenoid can have any voltage or Nema rated coils you desire, but must be our 3 position "center block" EV3 solenoid.
The wiring diagram for this setup is provided to any customer who wishes to wire this arrangement themselves. They will however require the appropriate switchbox and solenoid. UniTorq offers the service of wiring this arrangement at our factory. The includes running liquid tight conduit from each coil to the switchbox, and pre-wiring the solenoid coil wires to a separate terminal strip inside the Com7 switchbox. The cams will be factory set to operate the mid position at the center of the actuator stroke. The unit will be tested and a wiring diagram as well as cam setting instructions will be provided.
This setup will not work with spring return actuators. If end of travel indication is required two extra switches should be ordered with the switchbox. The inherent accuracy of this setup is approximately 2 to 5 degrees at mid position. It is possible to have two mid position settings with this setup. This would simply be one mid position when operating from close to mid and a second position when operating from open to mod. These are the two independent cam settings. The inherent inaccuracy is due to the fact that the two cam settings must never overlap thus the gap before overlapping is the 2 degree min. difference.
Principle of operation:
Utilizing a dual coil 3 position solenoid with the center position being blocked (EV3), the actuator will stop and lock in position whenever both coils are de-energized. Thus during the actuator stroke if the actuator ports are lock it in its instant position, Normal operation would be to energize coil A to fully open, energize coil B to fully close. The mid position energizes coil A or B through the two switches. The cams are set so only the appropriate coil is energized and when the switch comes off the cam that is the locked actuator position. One cam for coil A is set to stop the actuator from open to its mid position, and the other cam from the closed position.