3-Position Actuator

https://zkfmw.en.alibaba.com/product/60632622974-218397610/Three_Position_Pneumatic_Actuator.html?spm=a2700.8304367.0.0.68S66q
3-Position pneumatic actuators provide an operation of 0°- 45°- 90°or 0°- 90°- 180°. The intermediate position is achieved by an external mechanical stop of movement on the 2 auxiliary pistons. This intermediate stop position adjustable e.g. 90° actuators can provide 20°, 30° 50°, 75° etc. The intermediate position is easily achieved by adjusting the external nuts located outside the two end-caps. 

Both type, double acting and spring return, are available. Field of application: For dosing, for exact filling and for any kind of services where on 90° rotation an intermediate stop position is desired.


In order to control the operation of 3-position pneumatic actuators, a system of solenoid valves controlling a sequence of air supplies to the actuator is required as described below:

Position 1 (Intermediate Position):
This position is achieved when air is supplied simultaneously to ports 2 and D whit exhaust air at ports 4 and C. In fact the air supplied at ports D forces the auxiliary pistons to the center and the rods serve as mechanical stops for the internal pistons stopping in the desired intermediate position.


Position 2 (Fully Open Position):
This position is achieved when air supplied to port 2 and port C (Air to port C may also be avoided) with exhaust air at port 4. In this condition air to port 2 permits air to the internal pistons to continue the opening stroke.


Position 3 (Fully closed Position):
This position is achieved when air is supplied to port 4 with exhaust air at port 2.