Double Acting Return Actuator (RDA) 

Air supplied to Port A forces the pistons apart and towards the end caps, with the exhaust air exiting through Port B. The counter-clockwise rotation on the valve stem is then achieved.

Air supplied to Port B forces the pistons together, with exhaust air exiting through Port A. The clockwise rotation on the valve stem is then achieved.

Note:

1. The standard rotation is clockwise for closing the valve and counterclockwise for opening the valve.

2. If the assembly direction of the piston is reversed, the standard rotation is counter clockwise for closing the valve and clockwise for opening. 

Process Diagram