685Sr Seal And O-Ring Replacement - Fisher 685SE Instructions Manual

685SE/685SR Piston Actuator
June 2017
Table 8. Tie Bolt Torque
BOLT DIAMETER
1/4­20
5/16­18
3/8­16
7/16­14
1/2­13
9/16­12
5/8­11
3/4­10
7/8­9
1­8
1­1/8­7
685SR Seal and O­ring Replacement
The following procedure is for the replacement of the internal piston seals, bearing seals, and O­rings.
1. Complete Actuator Removal procedures above. Using the same rigging and lifting points as in the Actuator
Removal section, place the actuator upright with the yoke (key 21) flat against the ground. Place either a flat piece
of plywood or cloth under the yoke to protect against damage. Using straps, secure the actuator to a solid structure
to prevent it from falling over.
2. Loosen tie bolt hex nuts (key 11) in a crisscross pattern. Remove tie rod hex nuts and lock washers (key 10).
3. Using the same lifting eyes as in the Actuator Removal procedure, lift or hoist the upper head (key 1) off of the
cylinder (key 4). Place the upper head onto wooden blocks or other material that will not cause damage with the
O­ring side facing up.
4. Remove O­ring (key 2) from the upper head (key 1) and clean the seal groove. Install lightly greased new O­ring into
upper head seal groove.
5. Remove tie bolts (key 3) from lower head (key 9).
6. Thread a suitable lifting eye into the free port on the top of the piston rod (key 17).
7. Lift or hoist the piston assembly (keys 5, 6, 7, 17, and 19) out from cylinder (key 4) and place on a flat surface upside
down.
8. Remove the wear ring (key 6) and quad seal (key 7) from the piston (key 5).
9. Thread locking compound is applied to the threads by the manufacturer during initial assembly. As a result,
disassembly will require heating to loosen the thread locking compound. To remove the piston rod O­ring (key 19),
heat the piston assembly using a torch and unthread the piston rod (key 17) from the piston (key 5).
10. After the piston rod (key 17) has completely cooled, remove the piston rod O­ring (key 19). Clean the piston rod
O­ring groove with a light degreaser. Lightly grease a new piston rod O­ring and install onto the piston rod.
11. Reinstall piston rod (key 17) onto piston (key 5) using thread locking compound.
12. Clean piston seal grooves. Install new lightly greased quad seal (key 7) onto piston (key 5).
13. Without grease, trim to length and then install a new wear ring (key 6).
14. Lift cylinder (key 4) vertically and place on a flat surface. Take extra precaution to avoid scratching or gouging the
inner diameter of the cylinder.
15. Remove the O­ring (key 2) from the lower head (key 9) and clean the groove with a light degreaser.
16. Lightly grease the new O­ring (key 2) and install on lower head (key 9).
17. Extract bearing assembly (keys 12, 13, 14, and 15) from outer spring cartridge (key 23) by removing the bearing
retaining ring (key 16).
12
TORQUE
N•m
8
15
26
39
60
84
115
198
313
445
662
Instruction Manual
D103799X012
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11
19
29
44
62
85
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