
SMB/SB Installation and Maintenance Manual
140-11000 • July 2003
7-21
Flow Control Division
Limitorque Actuation Systems
• Step No. 10 of Disassembly procedure—reinstall Elastic Stop Nut (piece #85) with the same number of turns as was used to
remove.
• Step No. 17 of Disassembly procedure—align Declutch Link (piece #9) with Declutch Lever (piece #10) to assure correct lever
positioning.
• Step No. 16 of Disassembly procedure—install the Worm Shaft Clutch (piece #50) with smaller set of lugs first to engage with
lugs on Handwheel Clutch Pinion (piece #42).
• Step No. 10 of Disassembly procedure—rotate Worm Shaft Clutch (piece #50) to engage splines on Worm Shaft (piece #43) to
replace Worm (piece #53). Replace Declutch Lever (piece #10) and Handwheel (piece #5) temporarily. Rotate handwheel in
opposite direction used to remove Worm to place actuator in manual operation.
• Step No. 9 of Disassembly procedure—before replacing Spring Cartridge Cap (piece #4), align Torsion Spring (piece #54),
which holds the Declutch Lever in its normal position. Remove Declutch Lever (piece #10) and replace Spring Cartridge Cap
(piece #4), and Spring Cartridge Plate with Gasket (piece #71 and 72). Do not bolt tightly. Depress Declutch Lever into manual
operation and, while holding down Declutch Lever, secure Spring Cartridge Cap (piece #4).
• Step No. 5 of Disassembly procedure—ensure the Motor Pinion (piece #40) is a tight fit on the motor shaft (preferably a light
press fit).
NOTE: The SMB-0 Motor Pinion (piece #40) is installed with the set screw lockwire between the gear teeth and the motor flange. On
the SMB-1 through 4, the gear teeth are between the set screw/lockwire and flange.
7.3.3 To Replace the Stem Nut Only
a
a
WARNING: Do not remove the Locking Nut (piece #30) with the actuator under load or with valve under pressure.
CAUTION: If valve must be left in service while the stem nut is replaced, the valve stem must be locked in such a way as to
prevent any movement of the valve stem.
1. Remove
Locking Nut (piece #30). The locking nut is staked in two places; locate the stakes and spot with a drill.
2. Clean all metal particles.
3. Lift
Stem Nut (piece #20) out of the top of the actuator.
If the actuator is mounted on a valve having a threaded stem, and stem nut removal is required, proceed as follows:
1. Remove
Locking Nut (piece #30).
2. Rotate
the
Handwheel (piece #5) to close the valve.
3. When the stem nut splines are free from the Drive Sleeve (piece #11), the Stem Nut may be rotated by hand for the remainder of
the length of the valve stem and replaced, if necessary.
4. On new stem nut, stake the top threads in two places. Install stem nut.
7.3.4 Gasket Instructions
All gaskets except the housing cover gasket are 1/32" thick ASTM F104 synthetic fiber.
The housing gaskets vary in thickness. To determine the correct size, proceed as follows:
1. Clean
Housing Cover (piece #3) and main Housing (piece #2) gasket surface.
2. Install
unit
Drive Sleeve assembly, including the Bearings (pieces #11, 20, 30, 16, 28, 75-78).
3. Install
Housing Cover and measure the gap between the Housing Cover and the main Housing.
4. Take measurement and add 10%. Use the closest nominal gasket thickness or combination available.