Installation, Operation and Maintenance Manual
MAN 689 Rev. 6
June 2021
Figure 20
27
Maintenance
Section 5: Maintenance
5.2
Special Maintenance
If there are leaks in the hydraulic cylinder, pneumatic cylinder or a malfunction in the
mechanical components, or in case of scheduled preventive maintenance, the actuator
must be disassembly and seals must be replaced with reference to the follow general
sectional drawing and adopting the following procedures.
!
WARNING
If the actuator can be operated, it is essential to take it to fail-safe position, with the spring
totally extended, otherwise the actuator should be disassembled from the valve and follow
these steps.
•
Remove the plug (26) from the cover of the adjustment screw (20).
•
Record the length between end flange and stop-setting screw, as in Figure 20.
•
Bring the adjustment screw back to the maximum (26) to let the spring loosen.
Stop setting
screw cover
Stop setting
screw
Plug
!
WARNING
Before disassembling the cylinder, make sure the above operation of spring release is done.