3-position (90° rotation) 3 position pneumatic actuators provide an operation of 0°- 45°- 90°. the intermediate position is achieved by an external mechanical stop of movement on the 2 auxiliary pistons (for spring return actuators it may be only one auxiliary piston). this intermediate stop position is adjustable from 0° to 90°, for example 5°, 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 air torque 3-position pneumatic actuators a system of solenoid
valves controlling a sequence of air supplies to the actuator is required as described below:
when ordering 3-position pneumatic actuators, add “3p” to the normal
actuator code and specify the desired stop position including the intermediate e.g. 0° - 45° - 90°.
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.