Engine Tune-Up
required to close it. Open the valve to the previously
determined position at which the "hunting" stopped.
Test the action of the governor by manually disturbing
the engine speed. The engine should return promptly
t o the original steady speed with only a small
overshoot. The correct valve setting will be between
1/8 and 1/2 turn open. Closing the valve farther than
necessary will make the governor slow in returning the
engine to normal speed after a load change.
Adjust Governor Speed Droop
INTERNAL DROOP ADJUSTMENT
The purpose of adjusting the speed droop is to
establish a definite engine speed at no-load with a
given speed at rated full-load.
The governor speed droop is set at the factory and
further adjustment should be unnecessary. However, if
the governor has been overhauled, the speed droop
Fig. 9 - External Droop Control on PSG
must be readjusted.
Isochronous Governor
NOTE: When the engine lubricating oil is cold,
The best method of determining the engine speed is
the governor regulation may be erratic.
by using an accurate tachometer.
Regulation will become increasingly stable as
the temperature of the oil increases.
If a full rated load can be established on the unit, and
the fuel rods, injector rack control levers and the load
2. Stop the engine and remove the governor cover.
limit have been adjusted, set the speed droop as
follows:
3. Loosen the lock nut and back off the maximum
speed adjusting screw approximately 5/8"
1. Start the engine and run it at approximately one-
half the rated no-load speed until the lubricating oil
4. Loosen the droop adjusting screw. Move the droop
temperature stabilizes.
bracket so that the screw is midway between the ends
of the slot in the bracket. Tighten the screw (Fig. 8).
5. With the throttle in the RUN position, adjust the
engine speed until the engine is operating at 3% to 5%
above the recommended full-load speed.
6. Apply the full rated load on the engine and readjust
the engine speed to the correct full-load speed.
7. Remove the rated load and note the engine speed
No Load
Full Load
52.5 cycles. 1050 rpm
50 cycles. 1000 rpm
62.5 cycles. 1250 rpm
60 cycles. 1200 rpm
52.5 cycles. 1575 rpm
50 cycles. 1500 rpm
62.5 cycles. 1875 rpm
60 cycles. 1800 rpm
TABLE 1
Fig. 8 - Adjusting Speed Droop
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