DECREASE SPEED
INCREASE SPEED
GOVERNOR ARM
EXTENSION
GOVERNOR LINKAGE
MAXIMUM SPEED STOP
DECREASE SPEED
MINIMUM SPEED STOP
FIGURE
21.
VARIABLE
SPEED
GOVERNORS
engine speed. Decreasing spring tension decreases
engine speed. The no load speed of the engine should
be slightly higher than the speed requirements of.the-
connected
load.
For example: If the connected load is
to turn at 3510 rpm, set the no load speed of the
engine at about 3600 rpm. Check speed with a
tachometer.
If a speed adjustment is needed, turn the speed
adjusting nut in to increase the speed or out to
decrease the speed (Figure 21).
Sensitivity Adjustment: The engine speed drop from
no load to full load should be not less than 100 rpm.
Check the engine speed with no load connected and
again after connecting full
load.
Do not exceed 4000
rpm at no
load.
"
The sensitivity of the governor depends upon the
position of the arm end of the governor spring. A
series of. holes in the governor arm. provides for
adjustment. To increase sensitivity, move the spring
toward the governor shaft. To decrease sensitivity,
move the spring toward the linkage end of the
governor arm.
If the setting is too sensitive, a hunting condition
(alternate increase and decrease in engine speed) will
result. If the setting is not sensitive enough; the speed
variation between no-load and full load conditions will
.be too great. Therefore, the correct sensitivity will
result in the most stable speed regulation without
causing a surge condition.
Always recheck the speed adjustment after a
sen-
sitivity adjustment. Increasing sensitivity will cause a
slight decrease in speed and will require a slight
increase in the governor spring tension.
Variable Speed Governor Adjustments: These
engines are adapted for use where a wide range of
speed settings is desired. The design of the variable
speed governors give an automatic increase in
sensitivity when the speed is increased and the result
is good stability at all speeds.
To adjust the variable speed governors, refer to
Figure 21 and the following:
1.
Run the engine and make necessary carburetor
adjustments.
2.
Adjust the throttle stop screw on thecarburetor to
allow a recommended minimum idling speed of
900 rpm. A lower minimum does not assure
smooth operation under
load.
3. Adjust the tension of the governor spring for
minimum speed.
, For governors having a manual control arm, set lever to
minimum speed with no load and adjust the spring tension for
ahout 1500 rpm.
For governors having a Bowdin wire remote control knob .
(NHC engines with mounted.engine controls), pull back the
knob and slide to the first notch (low.speed). Adjust speed to
about'1500 rpm (or the desired low speed) at no load by
turning the knob as required.
4.
Adjust the sensitivity/while operating at minimum
speed to attain the smoothest no load tb full load
operation as follows:
To decrease sensitivity (allow more speed drop
from no load to full load operation) move the
governor spring outward into a different groove
. or-hole in.the extension arm.
To increase sensitivity (closer regulation by the
governor which permits less speed drop from no.
•load to full load operation)-, move the governor
• spring inward into adifferentgrooveorhole in the
extension arm.
. 5, Apply a full load and shift the variable control to.
maximum.speed—moving the control arm to the
. - -righf or shifting the control knob and slide to the
., second notch. For the governor control with the
control arm, set the screw in the bracket slot to
stop lever travel at the desired maximum full load
speed position. For the control with the control
knob and slide, increase or decrease speed by
turning the knob as required.
Approximately 3000 rpm is the recommended max-
imum full load.speed for continuous operation. The-
speed must agree with the load requirements... -
23
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