Kenworth T410, Driver'S Handbook Manual

Page: 215 / 418

CAT: 8612 November 2019 Page 189
OPERATING INSTRUCTIONS
Climbing and Descending
When approaching an uphill grade, apply light throttle early to build up
engine temperature gradually, so that when power is applied for the climb,
the engine won’t be subjected to a sudden, large heat change. Use
the tachometer and pyrometer to maintain optimum power/temperature
relationship during the climb.
As you approach the top of the grade, begin easing up on the throttle to
allow engine temperature to dissipate gradually. This technique can be
a real engine-saver when cresting a hill just prior to beginning a descent
down the other side. Running uphill at full throttle, then quickly coming
off the throttle entirely as the descent begins, puts punishing stresses on
the engine.
Downhill Grades
Gear selection is critical when descending hills. Engine overspeed can
occur when using the engine as a brake because the engine governor
does not function as a brake. A rule-of-thumb for gear selection is to go
down a hill in the same gear used to climb it.
If engine rpm approaches the top limit, apply brakes or shift up to a higher
gear. Use regular moderate brake application to bring speed to about
10km below desired speed, and release the brakes to allow the truck to
speed up again.
This procedure allows all brakes to contribute to brake performance,
whereas a light continuous application can cause one axle to do all the
braking.
Mountain Driving
Approaching an uphill grade, apply throttle to build up engine temperature
gradually and be in the best power range for the climb. As you approach
the summit, shift down one or two gears to allow the engine to cool down
slowly, especially if you are going to descend on the other side.
Level Cruising
If the pyrometer indicates excessive temperature while cruising, ease off
slightly on the throttle. Normally, on a smooth, level road, there should
be no loss of rpm and speed, and the pyrometer should indicate a drop in
temperature. If rpm and speed begin to drop, and the temperature remains
high, shift down one step to maintain speed and allow the temperature
to stabilise. Conversely, if the pyrometer indicates consistently low
temperature, then shift up one step and monitor the pyrometer.