WTR Series
Maintenance
L120 Installation & Maintenance Manual 120-11000 A
Stem Nut Replacement - Thrust Base Applications
This section is only applicable to thrust base applications. Occasionally the operator stem nut
may need replacing if used in a threaded stem application on rising stem valves.
a WARNING: Possible Hazardous Voltage. Turn power OFF before disassembling or
removing the actuator from the mounting base. This will prevent accidental start-up
during service to the unit.
a WARNING: Potential High Pressure Vessel. Before removing or disassembling the
actuator, ensure that the valve or other actuated device is isolated and not under
pressure.
To replace the stem nut:
1. Disconnect all incoming power to the actuator.
2. Remove actuator from the valve.
3. Remove Seal Retainer (piece #102 of Figure 10) followed by stem nut, bearings, and seals.
4. Check the fit of the new stem nut on the valve stem - ensure that the nut travels freely
without binding.
5. Reassemble the thrust base and remount the actuator on the valve.
6. Remount the actuator on the thrust base.
7. Removing the actuator from the valve will change the limit switch settings. Re-set the limit
switch in accordance with Section Setting Limit Switch.
8. Reconnect power.
9. Test for correct functioning.
Reassembly
Piece numbers refer to Figures 9, 10, 11 and 12.
1. Install Lug Ring (piece #20) onto Drive Sleeve (piece #25) followed by the Worm Gear
(piece #21). Ensure that the worm gear lugs engage with recesses on lug ring.
2. Install Spirolox retainer (separate layers of retainer sufficiently to begin threading the
retainer into the drive sleeve groove. Continue threading until the retainer is firmly
located in the groove).
3. Install Key (piece #23) and Clutch Sleeve (#19).
4. Add the Declutch Spring (piece #24), Bevel Gear (piece #18), Upper Bearing (piece
#17), and Lower Bearing (piece #16) to complete the assembly.
5. Replace the drive sleeve assembly into main housing, and secure with the Housing Cover
(piece #27). Ensure that all the seals are in place.
6. Insert Wormshaft Assembly (piece #15) into the housing and locate the bearings in the
housing journals. Replace the Wormshaft Cap (piece #5).
7. Install the Wormshaft Gear (piece #35) and Flex Loc Nut (piece #37).
NOTE: It is recommended that a new flex loc nut be used during reassembly.
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