The governor system controls engine speed with and
without load. The system consists of a governor cup
with steel flyballs on the camshaft, a yoke, shaft, and
arm, governor spring and adjusting screw, and
linkage to the carburetor.
Variations
in
engine speed change the position of the
governor cup on its shaft. This change is transmitted
by the shaft, arm, and linkage to the carburetor
throttle lever. Engine speed is determined by the
tension on the governor spring. Sensitivity (speed
drop from no-load to full-load) is controlled by the
number of spring coils used. More coils give less
speed drop from no-load to full-load (greater sen-
sitivity).
MAINTENANCE
Periodically lubricate the governor linkage with
lubricating graphite or light non-gumming oil. Also,
inspect the governor linkage for binding or excessive
slack or wear.
Adjustments
Prior to Spec
R,
both the governed speed and the
governor sensitivity are adjusted with the stud and nut
on the front of the engine air housing (Figure
50).
Beginning with Spec
R,
the sensitivity
is
adjusted with
an adjusting ratchet.
Speed Adjustment (Prior to Spec
R):
To adjust the
governed speed, hold the governor spring stud in
position and turn the governor spring nut with a
wrench. A mechanical tachometer may be used for
speed adjustment.
Sensitivity Adjustment (Prior to Spec
R):To adjust the
sensitivity, turn the governor spring stud; turning
counterclockwise gives more sensitivity (less speed
drop). If the governor is too sensitive, a hunting
condition occurs (alternate increasing and decreas-
ing speed). Adjust for maximum sensitivity without
hunting. After a sensitivity adjustment, the speed may
req u
i
re readjustment.
Speed Adjustment (Begin Spec
R):
Adjust engine
speed (RPM) by turning governor speed adjusting
nut, Figure
50.
Turn nut clockwise to increase speed,
counterclockwise to decrease speed.
Sensitivity Adjustment (Begin Spec
R):
Sensitivity
(no-load to full-load speed droop) is adjusted by
turning the sensitivity-adjusting ratchet nut accessi-
ble through hole in side of blower housing. If speed
drops too much when full load is applied, turn the
ratchet nut counterclockwise to increase spring ten-
sion and compensate for reduced rpm. An over-
sensitive adjustment, approaching no speed drop
when load
is
applied, may result in a hunting condi-
tion (alternate increase and decrease in speed).
After adjusting speed and sensitivity, replace the dot
button in blower housing (air-cooled units
only)
and
secure speed stud lock nut.
If the governor is too sensitive or not sensitive
enough, and can’t be adjusted with the stud or
ratchet, the sensitivity can be coarsely adjusted by
changing spring attachment on the governor arm.
Moving this point further from the governor shaft
decreases the governor’s sensitivity.
39
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