governor. the power piston will drop allowing the fuel
rod to return to the no-fuel position; thus the
hydraulic governor also acts as an automatic shut-
continually due to the fluctuating loads; therefore, a
means must be provided to control the amount of fuel
required to hold the engine speed reasonably constant
during such load fluctuations. To accomplish this
control, one of three types of governors is used on the
Fluctuations of the engine speed usually indicates
engine, depending upon the application. Installations
requiring maximum and minimum speed control,
governor malfunction. However, these fluctuations can
together with manually controlled intermediate speeds,
also be caused by an excessive load on the engine,
ordinarily use a limiting speed mechanical governor.
misfiring, or binding linkage. Contact an authorized
Detroit Diesel Allison Service Outlet for information
Applications requiring a near constant engine speed,
under varying load conditions that may be changed by
the operator, are equipped with a variable speed
mechanical governor. The hydraulic governor is used
where a uniform engine speed is required, under
Output Shaft Governors
varying load conditions, with a minimum speed droop.
On certain applications equipped with a Torqmatic
converter, it is sometimes desirable to maintain a
constant output shaft speed regardless of the engine
speed or load fluctuations. To acquire the necessary
results. a governor driven by the output shaft is
Mechanical governors are lubricated by oil that is
installed in conjunction with an engine governor. This
sprayed from an orifice in the front blower end plate.
governor is called an output shaft governor and may
This orifice directs a stream of oil into the revolving
be mechanical or hydraulic.
governor weights. The weights throw the oil to all
moving parts within the governor.
The output shaft governor controls the engine
governor (usually a limiting speed type) in the engine
Surplus oil returns to the engine crankcase through
speed range between idle and maximum speed. The
connecting passages in the blower and cylinder block.
engine speed is prevented from going below idle or
exceeding the maximum speed setting by the engine
When an engine equipped with a hydraulic governor
is running, oil is supplied under pressure from the
engine to the governor and a portion of the oil flows
past the power piston and pilot valve plunger to
lubricate the moving parts in the governor housing.
Oil which collects on the floor of the governor housing
Refer to the Engine Tune-Up Procedures for any
drains into the drive housing, thus providing
adjustments to the output shaft governors or contact
lubrication for the drive and driven shafts and their
an authorized Detroit Diesel Allison Service Outlet for
bearings. If the engine should fail to supply oil to the
information regarding output shaft governors.