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 (5) Injector rack may stick due to cramping
the fuel injectors by a fuel rod or link, attached to a lever on
caused by the rack control lever being out of position or
the injector control shaft. Fuel is decreased by action of fuel
cocked. Loosen screws in rack control lever. If this relieves
rod spring and increased by the opposing action of a hydraulic
the binding, move the lever on the control tube until the rack
servo-piston inside of a cylinder. Admission of oil to the
control lever no longer cramps the injector rack. Binding of
servo-cylinder is controlled by a pilot valve, which, in turn, is
the rack control lever may also be caused by damage to the
controlled by the flyweights of the governor.
The two
ends of the adjusting screws or the surfaces which they
flyweights are mounted on a vertical shaft and driven through
contact. Correct by filing. After correcting the bind or
a pair of miter gears from the upper rotor shaft of the blower.
damage, adjust the rack control lever to proper position.
Centrifugal force of the flyweights in rotation is opposed by a
(6) Control tube may stick or turn hard in control
speeder spring located on the vertical shaft between a spring
tube brackets. Binding due to poor alignment of control tube
fork at the top and the arms of the flyweights at the bottom.
brackets can be corrected by loosening bracket bolts and
Compression of the speeder spring, which is controlled by the
realigning brackets.
throttle, determines the speed at which the governor will
control the engine. To insure stability (without hunting) of
governor operation, speed droop, adjustable in amount, is
NOTE
introduced into the governor system. Adjustable speed droop
When the injector rack control tube is
is achieved through a slotted bracket, attached to the side of
free of binding and is operating the
the terminal lever, which carries a pin riding in a slot of the
injector racks properly, the tube will be
floating lever. Moving the droop adjusting bracket (speed
returned to the NO FUEL position by the
adjusting lever bracket) in toward the engine increases
tube return spring. When the control
governor droop, and out away from the engine, decreases the
tube brackets have been loosened, the
governor droop. (In starting a cold engine, several cranking
adjustments of rack control levers must
periods are required to increase lubricating oil pressure
be checked.
sufficiently to operate the governor and open the throttle so
that the engine can start. Starting time can be shortened by
(7) Pin in link that connects governor to control
pulling out on the fuel rod knob at the front side of the
tube may be binding in the control tube lever.
governor, thus, taking control away from the governor. The
(8) If speed variations are erratic, but slight, the
engine can be stopped regardless of the governor, by pushing
fault may lie in the governor drive. Excessive backlash in the
in on the fuel rod knob. Considerable force must be exerted
coupling or the miter drive gears, or too tight a meshing of the
to do this as the oil pressure against the servo-piston must be
latter, may cause this condition. If for any reason, such as
overcome. Besides holding the engine speed constant under
worn blower rotor bearings, rubbing of the rotors on the
varying load conditions, the hydraulic governor acts as an
housing, or the load on the flexible coupling between the
automatic engine shutdown device in case of lubricating oil
blower and the engine varies, this variation will be transmitted
pressure failure. If the engine fails to supply oil to the
to the governor as a speed change. The governor will attempt
governor, the servo-piston will drop, the fuel link will return to
to compensate for this by changing the fuel rod position. No
the NO FUEL position, and the engine will stop.
amount of adjustment or work on the governor can correct
b. Maintenance and Adjustment. Governor faults are
this condition.
usually indicated by speed variations of the engine, but all
c. Governor Adjustment. After installing governor on
speed variations do not necessarily indicate governor faults.
engine, adjustments enumerated below should be carried out
Therefore, when improper speed variations appear the
in the order shown. All adjustments, except maximum speed
following procedures should be carried out:
adjustments, are made with engine stopped. Adjustments
(1) Check load to be sure that speed changes
should be made only after an engine reaches normal
observed are not the result of load fluctuations.
operating temperatures.
(2) If load is uniform, check the engine to be sure
(1) Governor linkage adjustment.
that all cylinders are firing properly.
(2) Fuel rod adjustment.
(3) Check governor and operating linkage to
(3) Position injector control racks.
make sure that no bind exists between governor and engine or
(4) Maximum fuel adjustment (load limit
the injector control tube on its mounting brackets.
screw).
(4) Injector rack may stick or move too hard due
(5) Speed droop adjustment.
to the injector holddown crab being too tight or not properly
(6) Maximum speed adjustment.
positioned. This condition can often be eliminated by placing
d. Governor Linkage Adjustment. When the
a long punch or screwdriver on the foot of the crab and
tapping lightly with a small hammer.
5-59
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