Fisher 657 - Manual (Page 15)

Instruction Manual
D100307X012
657 Size 80 and 100 Actuators
December 2010
15
Instructions are given below for complete disassembly and assembly. Perform the disassembly only as far as necessary
to accomplish the required maintenance; then, begin the assembly at the appropriate step.
Key numbers refer to figure 5 for actuator parts and figure 8 for handwheel parts.
Disassembly
1. Bypass the control valve. Reduce the loading pressure to atmospheric (refer to the Maintenance section), and
remove the tubing or piping from the diaphragm casing.
WARNING
To avoid personal injury from the precompressed spring force thrusting the upper diaphragm casing (key 1) away from the
actuator, relieve spring compression (step 2, below), and carefully remove casing cap screws (key 124) (step 3, below).
2. Rotate handwheel counterclockwise, relieving all spring compression.
3. Unscrew cap screws (key 124), and remove gear case cover (key 123).
4. Loosen the set screws (key 41) in the front and back worm retainers (keys 48 and 49) and handwheel (key 51).
5. Remove retaining ring (key 118), and remove handwheel.
6. Remove front and back worm retainers (keys 48 and 49).
7. Remove worm shaft (key 45).
8. Pull the power screw assembly (key 122). The bearing and gear retainer, thrust bearing, and worm gear (keys 66, 67
and 44) will come out with the power screw.
Assembly
1. Pack the ball bearings (key 50) with lithium grease lubricant (key 241), and insert one ball bearing into the back
worm retainer (key 49).
2. Thread the back worm retainer and ball bearing into the gear case. Align the slot in the worm retainer with the set
screw hole in the gear case, insert set screw (key 41), and tighten.
3. Coat the worm shaft (key 45) threads with lithium grease lubricant, and slide the shaft into the gear case so that the
end of the shaft fits snugly in the back worm retainer.
4. Insert the bearing into the front worm retainer (key 48), and thread the retainer and ball bearing into the gear case.
Align the slot in the retainer with the hole in the gear case, insert the set screw (key 41), and tighten.
5. Slide the handwheel onto the worm shaft (key 45), and install retaining ring (key 118).
6. Pack the two thrust bearings (key 67) with lithium grease lubricant. Install one thrust bearing, then the worm gear
(key 44), followed by the second thrust bearing and the bearing and gear retainer (key 66).
7. Coat the power screw threads (key 122) with lithium grease lubricant. Slide the power screw into the thrust bearing
(key 67), turn the handwheel, and feed the sleeve through the worm gear.
8. Adjust set screws (key 40) to eliminate free play in the bearings.
Note
Over‐tightening the set screws will make handwheel operation difficult.
9. Install gear case cover (key 123), and tighten cap screws (key 124).
Parts Ordering
Each actuator has a serial number stamped on the nameplate. Always refer to this number when corresponding with
your Emerson Process Management sales office regarding replacement parts or technical information. Also, always
refer to the 11‐character part number of each needed part as found in the following parts list.