2.7
DETROIT DIESEL 53
M E C H A N I C A L GOVERNORS
it and, if necessary, recondition it as outlined in
Horsepower requirements on an engine may vary due
Section 2.1 or 2.1.1.
to fluctuating loads; therefore, some method must be
provided to control the amount of fuel required to
3. Check for bind that may exist in the governor
hold the engine speed reasonably constant during load
operating mechanism or in the linkage between the
fluctuations. To accomplish this control, a governor is
governor and the injector control tube.
introduced in the linkage between the throttle control
and the fuel injectors. The following type of
With the fuel rod connected to the injector control
mechanical governor used:
tube lever, the mechanism should be free from bind
throughout the entire travel of the injector racks. If
1. Limiting Speed Mechanical Governor.
friction exists in the mechanism, it may be located and
corrected as follows:
1. If an injector rack sticks or moves too hard, it may
Engines requiring a minimum and maximum speed
be due to the injector hold-down clamp being too tight
control, together with manually controlled intermedi-
or improperly positioned. To correct this condition,
ate speeds, are equipped with a limiting speed
loosen the injector clamp, reposition it and tighten the
mechanical governor.
clamp bolt to 20-25 lb-ft torque.
2. An injector which is not functioning properly may
have a defective plunger and bushing or a bent
injector rack. Recondition a faulty injector as outlined
in Section 2.1 or 2.1. 1.
3. An injector rack may bind as the result of an
improperly positioned rack control lever. Loosen the
rack control lever adjusting screws. If this relieves the
bind, relocate the lever on the control tube and
The governor has an identification plate
position the rack as outlined in Section 14.
located on the control housing, containing the
governor assembly number, type, idle speed range and
4. The injector control tube may bind in its support
drive ratio. The maximum engine speed, not shown on
brackets, thus preventing free movement of the
the identification plate, is stamped on the option plate
injector racks to their no-fuel position due to tension
attached to the valve rocker cover.
of the return spring. This condition may be corrected
by loosening and realigning the control tube
supporting brackets. If the control tube support
brackets were loosened, realigned and tightened, the
Check Governor Operation
injector racks must be repositioned as outlined in
Section 14.
Governor difficulties are usually indicated by speed
variations of the engine; however, it does not
5. A bent injector control tube return spring may cause
necessarily mean that all such speed fluctuations are
friction in the operation of the injector control tube. If
caused by the governor. Therefore, when improper
the spring has been bent or otherwise distorted. install
speed variations are present, check the engine as
a new spring.
follows:
6. Check for bind at the pin which connects the fuel
1. Make sure the speed changes are not the result of
rod to the injector control tube lever; replace the pin.
excessive load fluctuations.
if necessary.
If, after making these checks, the governor fails to
2. Check the engine to be sure that all of the cylinders
control the engine properly, remove and recondition
are firing properly (refer to Section 15.2). If any
the governor.
cylinder is not firing properly, remove the injector, test
SEC. 2.7 Page 1
November, 1973
