DETROIT DIESEL 53
LIMITING SPEED MECHANICAL GOVERNOR
The limiting speed mechanical governor (Fig. 1)
performs the following functions:
1. 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 Iimiting 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
The governor holds the injector racks in the advanced
fuel position for starting when the throttle control
lever is in the idle positron 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.
Fig. 1 - Governor Mounting
When the centrifugal force of the revolving governor
weights balances out the tension on the high or low
against their stops, and the high speed weights are not
speed spring (depending on the speed range), the
exerting enough force to overcome the high speed
governor stabilizes the engine speed for a given setting
spring. As the speed continues to increase, the
of the speed control lever.
centrifugal force of the high speed weights increases
until this force can overcome the high speed spring
In the low speed range, the centrifugal force of the low
and the governor again takes control of the engine.
and high speed weights together operate against the
limiting the maximum engine speed.
low speed spring. As the engine speed increases, the
A fuel rod, connected to the differential lever and the
centrifugal force of the low and high speed weights
injector control tube lever, provides a means for the
together compresses the low speed spring until the low
governor to change the fuel settings of the injector
speed weights are against their stops, thus limiting
their travel, at which time the low speed spring is fully
The engine idle speed is determined by the force
compressed and the low speed spring cap is within
exerted by the governor low speed spring. When the
.0015 " of the high speed spring plunger.
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
Throughout the intermediate speed range the operator
equal the force exerted by the governor low speed
has complete control of the engine because the low
speed gap is closed and the low speed weights are
April, 1971 SEC. 2.7.1 Page 1