DETROIT DIESEL 53
2.7.1
LIMITING SPEED MECHANICAL GOVERNOR
IN-LINE ENGINE
The limiting speed mechanical governor (Fig.1) performs the
following functions:
I.
Controls the engine idle speed.
2. Limits the maximum operating speed of the engine.
The mechanical engine governors are identified by a name
plate attached to the governor housing. The letters D.W.-
L.S. stamped on the name plate denote a double-weight
limiting speed governor.
The governor is mounted on the rear end plate of the engine
and is driven by a gear that extends through the end plate
and meshes with either the camshaft gear or the balance
shaft gear, depending upon the engine model.
Operation
The governor holds the injector racks in the advanced fuel
position for starting when the throttle control lever is in the
idle position. Immediately after starting, the governor moves
the injector racks to the position required for idling.
The centrifugal force of the revolving governor low and high
speed weights is converted into linear motion which is
transmitted through the riser and operating shaft to the
operating shaft lever. One end of this lever operates against
the high and low speed springs through the spring cap, while
the other end provides a moving fulcrum on which the
differential lever pivots.
When the centrifugal force of the revolving governor weights
balances out the tension on the high or low speed spring
(depending on the speed range), the governor stabilizes the
engine speed for a given setting of the speed control lever.
In the low speed range, the centrifugal force of the low and high speed weights together operate against the low
speed spring. As the engine speed increases, the centrifugal force of the low and high speed weights together
compresses the low speed spring until the low speed weights are against their stops, thus limiting their travel, at
which time the low speed spring is fully compressed and the low speed spring cap is within .0015" of the high
speed spring plunger.
Throughout the intermediate speed range the operator has complete control of the engine because the low
speed gap is closed and the low speed weights are Fig. 1 - Governor Mounting against their stops, and the
high speed weights are not exerting enough force to overcome the high speed spring. As the speed continues
to increase, the centrifugal force of the high speed weights increases until this force can overcome the high
speed spring and the governor again takes control of the engine, limiting the maximum engine speed.
A fuel rod, connected to the differential lever and the injector control tube lever, provides a means for the
governor to change the fuel settings of the injector rack control levers.
The engine idle speed is determined by the force exerted by the governor low speed spring. When the
governor speed control lever is placed in the idle position, the engine will operate at the speed where the force
exerted by the governor low speed weights will equal the force exerted by the governor low speed spring.
April, 1971 SEC. 2.7.1
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