freightliner 108SD, Driver Manual

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NOTICE
Engage the differential lock only when the ve-
hicle is stopped or moving slowly at low speed,
less than 5 mph (8 km/h). Engaging the differen-
tial lock at high speeds can cause internal axle
damage.
1. With the engine running, press the upper half of
the differential lock switch to engage the differen-
tial lock.
2. If the vehicle is moving, briefly let up on the ac-
celerator to relieve torque on the gearing, allow-
ing the differential to fully lock.
WARNING
Be especially careful when driving under slippery
conditions with the differential locked. Though
forward traction is improved, the vehicle can still
slip sideways, causing possible loss of vehicle
control, personal injury, and property damage.
3. Drive cautiously and do not exceed 25 mph (40
km/h). When the differential is fully locked, the
turning radius will increase because the vehicle
understeers. See
Fig. 15.3 .
4. Press the upper half of the differential lock switch
again to disengage the differential lock after leav-
ing poor road conditions.
NOTE: If the differential lock is engaged when
the engine is shut down, the differential lock will
disengage.
5. If the vehicle is moving, briefly let up on the ac-
celerator to allow the wheels to fully unlock, then
resume driving at normal speed.
Single Drive Axles with Traction
Equalizer
Some single drive axles are equipped with a traction
equalizer that is a load-sensing, self-actuating fea-
ture. A traction equalizer provides normal differential
action where traction is good. When one wheel be-
gins to spin faster than the other, clutch plates in the
differential housing automatically engage, delivering
power to both wheels. There is no operator control
with this feature.
NOTICE
Tire sizes on both rear wheels should be the
same on axles equipped with a traction equalizer.
If not, excessive wear may occur in the traction
equalizer.
Interaxle Lock, Tandem and
Tridem Axles
The interaxle lock (axle lock, interaxle differential
lockout) feature causes the drive axle shafts to rotate
together, and is recommended for use under adverse
road conditions where greater traction is needed.
See the axle manufacturer’s website for more infor-
mation.
When engaged, the interaxle lock essentially makes
the driveshaft a solid connection between the drive
axles. Power entering the forward axle is transmitted
straight through to the rearmost axle(s). Driveline
torque is now delivered equally and the drive axles,
and wheels, turn together at the same speed. The
interaxle lock increases drivetrain and tire wear and
should be used only when improved traction is
required.
Interaxle Lock Switch
The interaxle lock switch ( Fig. 15.4 ) allows the driver
to lock the drive axles together.
02/09/96
f350079a
A
B
A. Turning Radius When the Differential Lock is
Engaged (understeer condition)
B. Turning Radius When the Differential Lock is
Disengaged
Fig. 15.3, Turning Radii
Drive Axles
15.2