June 2021
Installation, Operation and Maintenance Manual
MAN 689 Rev. 6
32
Maintenance
Section 5: Maintenance
5.2.2
Replacement of Hydraulic Cylinder Seals
If there are leaks in the hydraulic cylinder or a malfunction in the mechanical components,
or in case of scheduled preventive maintenance, the actuator must be disassembled
and seals must be replaced with reference to the sectional drawing and adopting the
following procedures:
1.
Remove the nuts (item 16) and the washers (item 15) from the tie rods (item 10)
at the end flange (item 13) side.
2.
Slide off the end flange and the tube (item 12).
3.
Slide off the piston rod from the head flange (item 2).
5.2.2.1
Seals replacement
Prior to reassemble check that the actuator components are in good conditions and clean.
Lubricate all the surfaces of the parts, which move in contact with other components, by
recommended grease (AGIP-ENI HTX-SIL if seals are in NBR/Viton or Neoprene rubber, with
Aeroshell Grease 7 if the seals are in Fluorosilicon rubber). If the O-ring must be replaced,
remove the existing one from its groove, clean the groove carefully and lubricate it with
protective grease film. Assemble the new O-ring into its groove and lubricate it with a
protective grease film.
1.
Replace the O-rings (3) of the head flange (2).
2.
Replace the O-ring (3) of the end flange (13).
For replacement of piston rod seal ring (4) and of the O-ring (5) proceed as follows:
1.
Remove the existing Teflon seal ring (4) and the O-ring (5) from their groove.
2.
Clean the groove carefully and lubricate it with a protective grease film.
3.
Assemble the new O-ring into its groove and lubricate it with a protective
grease film.
4.
Assemble the new Teflon seal ring (4) into the flange groove, on the rubber
O-ring (5), by bending it : take care that the bending radius is as large as possible
to avoid damaged the seal. Then enlarge the seal ring with your fingers so as to
restore its round shape: pay attention not to utilise any tools, which can damage
the seal ring.
To replace the piston seal ring (9) and the O-ring (19) proceed as follows:
1.
Remove the existing Teflon seal ring (9) and the O-ring (19) from their groove.
2.
Clean the groove carefully and lubricate it with a protective grease film.
3.
Assemble the new O-ring into its groove and lubricate it with a protective
grease film.
4.
Assemble the new Teflon seal ring (9) on its rubber O-ring (19) by introducing one
side of it into the groove and then enlarge it with your fingers so as to introduce
it into the groove: take care to enlarge it uniformly without any tools which could
possibly damage it. The elastic memory of the kind of Teflon type the seal ring is
made of, allows the ring to shrink back to its previous dimension after a short time.
