Differential Locks - freightliner cascadia Driver Manual

Drive Axles

Differential Locks

Tandem Drive Axles with Interaxle
Differential Lock
An interaxle differential lock is standard on vehicles
equipped with tandem drive axles. It is driver-
actuated by means of a LOCK/UNLOCK control
valve switch located on the dash in the cab (see
Chapter 5 for more information about the switch).
Engagement can be at any speed, provided the
wheels are not slipping or spinning. A red indicator
illuminates when the interaxle differential lock is en-
gaged.
In the UNLOCK position, there is differential action
between the two axles. The differential compensates
for different wheel speeds and variations in tire size.
Keep the interaxle differential unlocked for normal
driving on roads where traction is good.
In the LOCK position, the interaxle differential is
locked out and the driveshaft becomes a solid con-
nection between the two axles. Power entering the
forward axle is also transmitted straight through to
the rear axle, so both axles turn together at the same
speed. The LOCK position should be used when the
vehicle encounters poor traction conditions; however,
it also increases drivetrain and tire wear and should
be used only when improved traction is required.
Interaxle Differential Lockout Operation
NOTICE
Do not actuate the interaxle differential control
valve while the tires are slipping. Do not operate
the vehicle continuously with the interaxle differ-
ential locked during extended good road condi-
tions. Using the IAD lock when wheels have good
traction can harm the axle, wear the tires exces-
sively, and increases fuel consumption. Release
the IAD lock as soon as road conditions permit it.
To lock the interaxle differential and achieve maxi-
mum pulling power when approaching slippery or
poor road conditions, move the lockout control valve
to LOCK while maintaining vehicle speed, before en-
countering the poor road conditions. Let up momen-
tarily on the accelerator to engage the differential
lock. Proceed over poor road conditions with caution.
Do not wait until traction is lost and the tires are
spinning before locking the interaxle differential.
16.1
To unlock the interaxle differential, move the lockout
control valve to UNLOCK while maintaining vehicle
speed, after leaving the poor road conditions. Let up
momentarily on the accelerator to allow the shift,
then resume driving at normal speed.
Driver-Controlled Differential Lock
(DCDL)
Some vehicles are equipped with a driver-controlled
differential lock (DCDL) that is operated by a dash
switch in the cab (see Chapter 5
tion about the switch). The differential lock provides
maximum traction for slippery conditions by forcing
the wheels on a drive axle to rotate together. The
differential lock should be engaged when the vehicle
is stopped or moving at a low, constant speed and
the wheels are not spinning, slipping, or losing trac-
tion. Do not exceed 25 mph (40 km/h) when the dif-
ferential lock is engaged.
On tandem axles there are three possible DCDL op-
tions:
•
Forward-rear carrier only
•
Rear-rear carrier only
•
Both rear carriers.
An indicator light comes on when the DCDL is en-
gaged. An optional buzzer can also be used to indi-
cate DCDL engagement.
The DCDL provides maximum traction under slippery
conditions. When the DCDL is engaged, the clutch
collar completely locks the differential case, gearing,
and axle shafts together, maximizing traction of both
wheels and protecting against spinout. Under normal
traction conditions, do not engage the DCDL; operate
the axle with differential action between both wheels.
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.
for more informa-