SMB/SB Installation and Maintenance Manual 140-11000 • July 2003 8-15
Flow Control Division
Limitorque Actuation Systems
8.5 SB-3
a WARNING: See Section 4.1 and 4.2 on Safety Precautions and Safety Practices before proceeding with
disassembly.
a WARNING: Extreme caution should be used in the disassembly and reassembly of the spring compensator
assembly.
The SB-3 actuator is a basic SMB-3 actuator with the housing cover, drive sleeve, and locknut modified to provide spring compression
to the stem nut. The disassembly/assembly procedure for the SMB-3 is applicable (Sections 7.3.1, SMB-0, 1, 2, 3, 4, and 4T
Disassembly and Section 7.3.2, SMB-0, 1, 2, 3, 4, and 4T Reassembly), with the following procedures replacing Step 11 and stem
nut removal procedure.
8.5.1 SB-3 Disassembly/Stem Nut Removal
Piece numbers refer to Figure 8.5.
1. Remove the Spring Housing (piece #140).
2. Remove the Spring Cartridge (piece #149), complete with Belleville Springs (piece #152), Thrust Washers (pieces #150 and
#153), Deflection Limit Sleeve (piece #161), and Spring Retainer Cap (piece #166).
NOTE: The spring assembly should not be disassembled unless absolutely necessary.
To disassemble the Spring Cartridge:
a. Remove the Spring Retainer Cap (piece #166). Be careful to remove the set screws securing the Spring Retainer Cap to the
Spring Cartridge before trying to remove Spring Retainer Cap .
b. Lift off Thrust Washer (piece #150), Belleville Springs (piece #152), Deflection Limit Sleeve (piece #161) and Thrust Washer
(piece #153).
To reassemble the Spring Cartridge:
a. Position Belleville Springs (piece #152) between the two Thrust Washers (pieces #153 and #150) as shown in Figure 8.5.
b. Thread the Spring Retainer Cap (piece #166) onto the Spring Cartridge (piece #149) until the Spring Retainer Cap touches the
Thrust Washer. Add 3/4 turn.
c. Reinstall set screws or drill and tap for new set screw locations.
d. Install Deflection Limit Sleeve (piece #161).
3. Remove the Bearing Cartridge (piece #154), complete with Bearing Cup and Cone (pieces #147 and #148).
4. Remove Centering Ring (piece #167) and the Drive Sleeve Bearing Cartridge (piece #3).
5. Remove Drive Sleeve (piece #11) in accordance with Step 12 of Section 7.3.1, SMB-0, 1, 2, 4, and 4T Disassembly. If only the
Stem Nut (piece #20) is to be removed, see Step 6.
6. If the actuator is not on the valve, the Stem Nut (piece #20) is accessible. If the actuator is on the valve, bolt the Drive Sleeve
Bearing Cartridge (piece #3) to the Housing (piece #2) using two 7/8” UNC x 9 UNC x 1-1/2" long bolts to hold the Bearing Cone
and Cup (pieces #77 and #78) in place.
a. Place the actuator in hand operation.
b. Rotate the Handwheel in the direction to effect a downward movement of the stem—usually the close direction. The Stem Nut
will climb up the stem until it clears its splines.
c. Rotate the Stem Nut off the stem.
8.5.2 SB-3 Reassembly/Stem Nut Installation
Piece numbers refer to Figure 8.5.
1. Replace the Stem Nut (piece #20).
a. If the actuator is not on the valve, the Stem Nut will drop in the Drive Sleeve (piece #11) until it bottoms out on the shoulder of
the Drive Sleeve. Ensure splines are engaged.
To Next Page
Loading...
Need help?
General
