Working Principle With Add-On - HKC ET Series Installation, Operation & Maintenance Manual

ET Series Heavy-duty Pneumatic Actuators
Installation Operation& Maintenance Manual

3.4. Working Principle with Add-on

This section explains the working principle of the Spring Return Actuator and solenoid valve attachment. When air is
provided to the center of cylinder through port A of the actuator, piston moves "outwards" due to air pressure. The rod is
connected with the piston which delivers power to the Yoke and during this time the Yoke turns counter-clockwise. This
changes the valve shaft to the open position. The power is delivered to the Yoke and spring rod compresses the spring thus
opening valve shaft. When the air is sent out through port A, the piston moves due to the compressed spring, and then the
Yoke operates clockwise hence valve shaft closes. The Spring Return Open/Close operating diagrams (Figure 3-2a and
Figure 3-2b) is as shown below.
Figure 3-2a. Open Mode Operating Principle / Fail Close
Figure 3-2b. Close Mode Operating Principle / Fail Close
Figure 3-3a. Close Mode Operating Principle / [Fail Open ---- 17 Rev0]
Figure 3-3b. Open Mode Operating Principle / [Fail Open ---- 17 Rev0]
Doc No. : HumG-ET-21 E Rev0 Page 9 / 17 Valve Automation Leader, HKC