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Actuator
(See Figure 5 and Figure 6)
The actuator consists of a stepper motor coupled to the
carburetor throttle shaft.
It receives signals from the governor control unit and
rotates the shaft to the proper position.
To test for proper operation of the actuator, disconnect
magnetic pickup leads.
shaft/governor stepper motor fully counterclockwise
(closed throttle). Start generator set. Actuator should
initially move clockwise (wide-open throttle) and then turn
completely counterclockwise.
remain in this position. Stop generator set. If actuator fails
this test, replace actuator.
The governor actuator should function with steady and
smooth movement during operation. If movement of
actuator is erratic or large changes in movement occur:
D Check shaft alignment— ensure that the actuator
and throttle shafts are concentric and that the
throttle-shaft pin is at midpoint of the actuator slot
D Check for excessive coupling slot wear— replace
worn parts
D Check for broken or loose wiring including plug
connections
Adjust coupling so throttle shaft pin is recessed to the
middle of the slot.
Stepper-motor rotational position adjustment is not
necessary. Throttle plate position can be either open or
closed during assembly.
Only two actuator leads of each coil group are utilized.
(BLK-YEL, and RED-WHT.) Resistance per phase: 38.5
ohms.
Voltage pulses received from the governor control
determine movement of the stepper motor.
A 12-VDC voltage applied to the motor leads will result in a
single-step movement of 1.8_ . Reversal of the voltage
polarity will result in a 1.8_movement in the reverse
direction.
The stepper motor will not continuously rotate with battery
voltage supplied to its windings.
4
Manually move the throttle
The actuator should
NOTE
NOTE
TOP VIEW
2
1
5
1
6
1. Actuator
2. Coupling
3. Closed throttle
4. Intake air flow
5. Pin
6. Set screw
7. Open throttle
Figure 5. Actuator (Stepper Motor)
BLK
YEL
GRN
Figure 6. Actuator Coil Group
4
4
TP-5572-6
RED WHT BLU
TP-5572-6
SB-555 5/96
3
7
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