Regional Haul Model Operator's Manual - Peterbilt Motors Company

INTERAXLE DIFFERENTIAL LOCK
than 25 mph, or while wheels are spinning or traction
is minimal; lock it before you encounter these conditions.
Understeer Condition
02871
2. Put the inter-axle differential lock switch, labeled
MAIN DIFFERENTIAL LOCK, in the LOCK position. A
light (DIFF LOCK) in the warning module on the dash
will turn on, indicating that the differential is locked
(engaged).
STARTING AND OPERATING THE VEHICLE
3. If you LOCK or UNLOCK the inter-axle differential
while moving, let up momentarily on the accelerator
pedal to relieve torque on the gearing and allow full
engagement of the clutch (the mechanism that locks
the wheels).
NOTE: If your vehicle has an automatic transmission,
it may be necessary to shift the transmission
to the Neutral position momentarily to
allow the main inter-axle differential lock splines
to fully engage or disengage.
4. Drive the vehicle through the poor traction area, keeping
your speed under 25 mph (40 km/h).
To UNLOCK the inter-axle differential:
1. When you reach dry pavement or better road conditions
where the differential lock is not needed, switch
the differential lock to UNLOCK.
2. Let up momentarily on the accelerator pedal to relieve
torque and allow the clutch to disengage.
3. When you unlock the differential, normal vehicle handling
will resume and the light on the warning module
will turn off.
– 126 – Y53-6033 Regional Haul (R05/10)