User Manual

SERIES 50 OPERATOR'S GUIDE
Engine Brakes and Cruise
Control
If your engine is equipped with
both cruise control and engine brake
retarders, the engine retarders can
operate automatically while you
are in cruise control. I f the cruise
control/engine brake function is turned
ON in the ECM (electronic contr ol
module) programming, the engine
retarders will come on “low” when
your set road speed increases a few
miles-per-hour (kilometers per hour)
above your cruise set speed. If your
speed continues to increase, the ECM
will increase the engine retarders'
braking power progressively. When
the vehicle returns to the set cruise
speed, the engine retarders will “turn
off” until you need them.
For safety reasons, don't use cruise
control when it is not possible to keep
the vehicle at constant speed due to:
□ Winding roads
□ Heavy traffic
□ Slippery pavement
□ Descending grades that call for
engine brake assistance.
For an exp lanation of the engine brake
retarder system and recomm endations
for proper operation, refer to section
ENGINE B RAKE SYSTEM.
Shifting
Depending on your transmissio n
model, the gear split may vary from
500 to 300 rpm. The electron ic
governor prov ides almost no overrun
capability; and, if the transmission
is downsh ift ed too early, you will
experience a temporary loss of pulling
power until the engine speed falls
below rated speed.
In general, when using a 7- or 9-sp eed
transmission, you should always
downshift between 1250 an d 1 300
rpm. This is true even on steep grades
with heavy loads. W h en using an
18-, 15- or 13-speed transmission,
youwillneedtodownshiftatan
rpm that allows “less th an rated”
rpm b efore throttle application in the
next gear down. You m ay want to
limit engine speed to 1900 rpm in all
gears. The Series 50 provides constant
horsepower from 1800 rpm through
2100 rpm, but fuel econom y is not as
efficient above 1800 rpm.
All information subject to change without notice. (Rev. 01/04) 39
DDC-SVC-MAN-0058 Copyright © 2004 DE TROIT DIESEL CORPORATION