Follow the directions in the
Cummins Operation and
Maintenance Manual
and in this manual for trouble-free,
economical vehicle engine operation.
1. Cummins diesel engines produce high horsepower
and peak torque characteristics at low rpm. Be-
cause of this, it is not necessary to keep the engine
"wound up" to deliver the required horsepower at
the wheels. These characteristics may also result in
less shifting, and make shifting at lower rpm (to
peak torque) more practical.
2. Depending on the vehicle gearing, the posted
speed limit can sometimes allow operation in either
of the top two gears; however, for improved operat-
ing efficiency (fuel economy and engine life), oper-
ate in the top gear at reduced rpm, rather than in
the next lower gear at the maximum rpm.
3. Cruise at partial throttle whenever road conditions
and speed requirements permit. This driving tech-
nique permits operating within the most economical
power range of the engine.
4. When approaching a hill, open the throttle smoothly
to start the upgrade at full power, then shift down
as desired, to maintain the optimum vehicle speed.
The high torque of Cummins engines may permit
topping some grades without shifting.
5. Cummins engines are designed to operate over a
wide speed range. More frequent shifting than nec-
essary does not allow proper utilization of this flex-
ibility. The driver who stays in top gear and uses
the wider speed range will achieve the best fuel
economy.
6. The Cummins diesel engine is effective as a brake
on downhill grades, but care must be used not to
overspeed the engine going downhill. The governor
has no control over engine speed when the engine
is being pushed by the loaded vehicle.
Never turn off the ignition switch while going down-
hill. With the engine still in gear, fuel pressure will
build up against the shutdown valve and may pre-
vent it from opening when the ignition key is turned
on.
CAUTION
Engine overspeed (engine speed exceeds high idle,
no-load rpm) can damage the engine.
7. Use a combination of brakes and gears to keep the
vehicle under control at all times, and to keep the
engine speed below the rated governed rpm.
Cruise Control
The cruise control is activated by the ON/OFF and SET/
RESUME switches. The minimum speed at which cruise
Engines
4.6
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