Fisher 657 - Manual (Page 14)

Instruction Manual
D100307X012
657 Size 80 and 100 Actuators
December 2010
14
The actuator should be equipped with a side‐mounted handwheel, which is designed for more frequent use as a manual
operator.
A top‐mounted handwheel assembly is normally used as an adjustable‐up travel stop to limit full retraction of the
actuator stem. Turning the handwheel clockwise turns the handwheel stem (key 133, figure 6) into the diaphragm
casing and forces the pressure block assembly (key 179, figure 6) against the diaphragm and diaphragm plate.
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 4 for actuator parts and figure 6 for handwheel parts.
Disassembly
1. Bypass the control valve. Reduce the loading pressure to atmospheric, and remove the tubing or piping from the
diaphragm casing (key 1).
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 141) (step 3, below).
2. Remove cover band (key 60). Insert a rod of approximately 12.7 mm (1/2‐inch) diameter into a hole in the adjusting
screw (key 12), and rotate the adjusting screw from right to left until spring compression is relieved. Rotate
handwheel to be sure it is not compressing actuator spring.
3. Unscrew cap screws (key 141), and remove handwheel assembly.
4. Remove hex nut (key 54), and lift off the handwheel.
5. Unscrew support screws (key 182), and remove pressure block, stem, stem collar, and thrust bearing (keys 179,
133, 183, and 175).
6. Unscrew body nut (key 186), and remove gland (key 180). If necessary, remove and replace packing rings (key
181).
Assembly
1. Install new packing rings and gland (keys 181 and 180), and thread the body nut (key 186) onto the body.
2. Lubricate the thrust bearing and stem (keys 175 and 133), with lithium grease lubricant (key 241). Slide stem, stem
collar, thrust bearing, and pressure block (keys 133, 183, 175, and 179) into the body as shown in figure 6 and
install support screws (key 182).
3. Install handwheel and hex nut (keys 51 and 54).
4. Install a new handwheel gasket (key 185).
5. Mount the handwheel assembly on the diaphragm casing, and secure with cap screws (key 141).
6. Reconnect pressure tubing or piping to actuator casing.
Size 100 Top‐Mounted Handwheel (Adjustable Up Travel Stop)
A top‐mounted handwheel assembly is normally used as an adjustable‐up travel stop to limit full retraction of the
actuator stem. Clockwise rotation of the handwheel (key 51) moves the actuator stem (key 10) downward,
compressing the spring (key 6). Spring action returns the stem as the handwheel is turned counterclockwise.