Governor Control Unit Adjustment - Hobart 140GT17P Operation And Maintenance Manual With Illustrated Parts List

OM-2029

(3) Governor Control Unit Adjustment

Before making an adjustment to the control unit (Fig. 6), make certain that linkage between actua-
tor lever (3, Fig. 4) and fuel control lever (7, Fig. 4) is properly adjusted. There must be no lost
motion or "play" in the linkage. Be sure magnetic pickup is producing a strong, normal output.
There are three adjustment controls on the unit (see Fig. 6) . They are identified as:
RATED SPEED - Adjusts engine speed and generator frequency.
GAIN and STABILITY - Together, these adjust engine response time and engine stability.
To adjust control unit, proceed as follows:
(a) If the control box is being adjusted for the first time, set adjustment control as follows:
RATED SPEED control - Set the rated speed control screw fully counterclockwise (to mini-
mum speed setting).
GAIN control - Set this control screw to mid position.
STABILITY control - Set this control screw to mid position.
NOTE: A VERY shall screwdriver is required for these adjustments.
(b) Start engine and allow it to warm up.
(c) Place engine-generator control switch (23, Fig. 1) in GEN position to make electric governor
functional.
(d) Turn RATED SPEED adjusting screw clockwise to increase engine speed to 1714 RPM. At
1714 RPM, the frequency meter (9, Fig. 1) will indicate 400-Hz.
(e) Adjust GAIN control screw to the stable region between low frequency and high frequency os-
cillation.
(f) If there is a low frequency oscillation which does not stop when the gain control is adjusted,
turn the STABILITY control screw slightly clockwise and try the GAIN control adjustment again.
Continue adjusting the STABILITY control screw slightly clockwise, then re-adjusting the GAIN
control screw until the engine runs at a steady speed.
If there is a high frequency oscillation which does not stop, even when the GAIN control screw is
turned fully counterclockwise, adjust the STABILITY control screw slightly counterclockwise until
the high frequency oscillation stops.
(g) The electric governor is now set to a nominally good operating point. Trim adjustments as de-
sired or required.
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March 16/90