Installation, Operation and Maintenance Manual
MAN 573 Rev. 8
July 2020
Figure 11
ON-OFF Service: Three way control valve
The Figure shows the simplest ON-OFF control. The control valve (2) has two positions. In one
position, the gas supply pressure is connected to the cylinder chamber, and the actuator performs
the “pneumatic” operation. In the other position the cylinder is connected to the exhaust and
the actuator moves under the operation of the spring. The control valve can have many types of
actuating devices (solenoid, manual control, pneumatic pilot, spring, etc.). Spring-Return control
valves allow “fail safe” operation.
1
2
Pressurized air
Atmospheric pressure air
Manual control
Pneumatic pilot
control
Solenoid
control
Figure 12
ON-OFF Service: Quick spring operation
When fast action is required under spring operation, a quick exhaust valve (3) is installed in the
cylinder directly port to exhaust the gas from the cylinder directly to the atmosphere. When the
control valve (2) opens to the atmosphere a differential pressure is created across the quick exhaust
valve (3) causing it to open. The resultant high flow capacity from cylinder to atmosphere allows
quick spring operation of the actuator.
1
3
2
Pressurized air
Atmospheric pressure air
Operation and Use
15
Section 3: Operation and Use
