How does the rotary actuator work?

What can it do and what does the 90 degree indicator mean?

According to the 2004 Pneumatics Manual, the rotary actuator we have access to is limited to 90degrees of motion. It is rated at 0.166 in-lbs/PSI, so at 60PSI, that works out to 9.96 in-lbs of torque.

It is designed to let you use compressed air to make a rotary movement -
maybe twist an arm or bracket or something else. It can replace an electric motor and potentiometer / limit switch set up., but you are limited on the cabability (basically 0 or 90 degrees and nothing in between).

Just from looking at it, I can guess (not certain) that there is a simple rack & pinion inside. The rack is pnuematically driven inside the cylinder, and the pinion is attached to the output thus making linear into rotary motion.

For this year, we are limited to 90 deg of rotation, but at our pnuematic workshop we were told there are limiting screws taht can be adjusted to let it turn up to 320 deg under internal limits only.

I think the main thing that anyone needs to keep in mind when they use them is that these are not motors. they canot complete a revolution, however thay can go from say tharting position, and turn 90 degrees. they might me usable at the end of an arm to close a grabber, since they are light.

Apply pressure to one side and the shaft rotates 90 degrees. The tolerance is minus 0 plus 15 degrees so it may turn up to 105 degrees. Apply pressure to the opposite side and it rotates back. For more information go to and download the Pneumatics manual.

Is it limited to on or off (0 or 90 degrees) or can you adjust it anywhere in between?

The pneumatics manual says this:

 "The rotational tolerance of the unit is 90 degrees –0 degrees +15   
 degrees. Exact angle adjustment should be made with external stops."

That sounds like to me that it is either 0 or 90 degrees.

You can always just gear it 4 to 1, and get an output to rotate 360 degrees, or any other gear ratio imaginable.

Not true. Their are capability between 0 and 90 and extend and retracted. I’m working on a white paper to show how. We used the capabilities on our pneumatic lift last year.

I had a question about the rotary actuator… are we allowed to order a rotary actuator that moves beyond 90 degrees? I was hoping for one that could move 180 degrees. Or is there some legal way of adjusting the rotary actuator to move beyond just the 90 degree limit… if so, how? Thanks very much!