Flowserve SMB Series Electric Actuators - Manual (Page 32)

SMB Series/SB Series Installation and Maintenance FCD LMENIM1401-04-AQ – 01/15
32
5
Operation
c WARNING: See Section 4.1 and 4.2 on Safety Precautions and Safety Practices prior to
operation.
5.1 Motor Operation
Actuator motors are high-starting torque, totally enclosed motors. The motors are furnished in
weatherproof, explosionproof, or submersible enclosures. The motors are furnished with ball bear-
ings and provided with grease seals. All three-phase AC motors are squirrel-cage design and all DC
motors are compound wound.
Piece numbers refer to Figure 7.9 through 7.11. However, this description is applicable to all models.
The piece numbers will differ for each model.
The electric motor has a Motor Pinion (piece #40) mounted on its shaft extension. This pinion drives
the Worm Shaft Clutch Gear (piece #41), which is engaged with the Worm Shaft Clutch (piece #50).
The Worm Shaft Clutch is splined to the Worm Shaft (piece #43). The Worm (piece #53) is splined to
the Worm Shaft (piece #43), and when it is rotated, it turns the Worm Gear (piece #16).
The Worm Gear has two lugs cast onto the top portion that engage the two lugs on the Drive Sleeve
(piece #11). These lugs are spaced so that when the Worm Gear begins to turn during motor opera-
tion there is a certain amount of lost motion before the lugs engage, causing the hammer blow effect
within the actuator.
As soon as the Worm Gear Lugs engage, the Drive Sleeve, splined internally with the Stem Nut (piece
#20), causes the stem nut to rotate and open or close the valve. The Stem Nut is threaded to fit the
thread of any rising stem valve. In the case of non-rising stem valves, the electric actuator may be
mounted in tandem with an additional gear drive, and the Stem Nut (piece #20) is bored and keyed to
fit the shaft.