Installation, Operation and Maintenance Manual
MAN 604-1A Rev. 6
March 2021
Maintenance
29
Section 5: Maintenance
5.2.3
Replacement of the Seals of Reduced-Manual
Override “MRHW”
NOTICE
Before any operation , you must keep the actuator in release position to allow the air and
spring stroke.
1.
Measure the protrusion of the stop screw (19) with reference to the surface of the
protection tube (6) end flange, so as to be able to easily restore the setting of the
actuator mechanical stop, once the maintenance procedures have been completed.
2.
Loosen the lock nut (20) and unscrew the stop screw (19) until it is removed from
the end flange of protection tube (6) together with the nut (20), the washer (34)
and the sealing washer (35).
3.
Rotate clockwise the handwheel (7) so to move backward the jackscrew (18) until
it hits the end flange of protection tube.
4.
Disassemble the manual override from the pneumatic cylinder end flange by
unscrewing the fastening screws (36).
5.
Disassemble the screw (31), which fasten the reduction unit to the spacer bracket (5).
6.
Move the reduction unit along the protection tube (6) till the key (13) is accessible.
Remove the key from the protection tube. Move the spacer bracket (5) along the
protection tube (6) till the O-ring (4) is accessible.
7.
Remove the O-rings (1-4) from their grooves. Carefully clean the grooves and
lubricate them with protective grease film. Assemble the new O-rings into their
grooves and lubricate them.
8.
Move the spacer bracket along the protection tube up to reach its working
position. Assemble the key (13). Move the reduction unit to its working position
and fasten it to the spacer bracket (5) by the screws (31).
9.
Remove the sealing washer (35) from the stop screw (19). Carefully clean and
lubricate the stop screw thread and the surface of the end flange area, on which
the sealing washer works. Screw the new sealing onto the stop screw until it
touches the nut (20).
10.
Assemble the washer (34) onto the sealing washer (35). Screw the stop screw into
the threaded hole of the end flange of protection tube until it hits the jackscrew
(18) of manual override.
11.
Actuate the manual override, by rotating anticlockwise the handwheel until it is
possible to screw the stop screw (19) till it reaches its previous position related to
fully open valve position (the same protrusion with reference to the surface of the
protection tube end flange as before the disassembly).
12.
Check that the sealing washer (35) and the washer (34) are in contact with the end
flange surface.
13.
Tighten the lock nut (20).
NOTICE
After maintenance operations carry out a few actuator operations (5-10) to check that
its movement is regular, that there is no air leakage through the seals and to to eliminate
any oil residues in the air circuit, deriving from the lubrication of the seals during the
replacement phase.
