Regional Haul Model Operator's Manual - Peterbilt Motors Company

STARTING AND OPERATING THE VEHICLE
corners and on dry pavement is more difficult. Continuous
operation on a paved, dry surface stresses the tandem
axles, possibly causing internal damage.
Use this feature only when driving on surfaces with poor
traction, such as wet slippery roads, heavy mud or snow,
or loose gravel. And do not use it when going downhill or
at speeds greater than 25 mph (40 km/h).
Lock the inter-axle differential when you encounter road
conditions such as these:
• Ice or snow — with or without tire chains.
• Dirt roads.
• Loose sand, mud, or other rough road conditions.
WARNING! Do not put the differential lock in
the LOCK position while the wheels are spinning
freely (slipping), you could lose control
of the vehicle, resulting in death, personal
injuryor property damage. Switch to LOCK
only when the wheels are not spinning.
• Look ahead for wet, muddy, or icy patches on the
road, stop your vehicle and switch to LOCK ahead of
time.
INTERAXLE DIFFERENTIAL LOCK
WARNING! Do not operate the vehicle on dry
pavement with the differential locked. This
could lead to an accident, resulting in death or
personal injury. On dry pavement, you will not
be able to steer well with the differential
locked. Lock the differential only when operating
on surfaces with poor traction, such as
wet, slippery roads or loose gravel.
Inter–Axle Differential Lock Operation
WARNING! Do not use the inter-axle differential
lock when travelling downhill or at speeds
above 25 mph (40 km/h). When it is engaged
under these conditions, your vehicle will
exhibit “understeer” handling characteristics.
This “understeer” condition will cause your
vehicle to turn less quickly and more steering
effort will be required, which can cause an
accident, resulting in death or personal injury.
To LOCK the inter-axle differential:
1. Anticipate when you might need increased traction,
slow down to a steady speed under 25 mph (40 km/h)
or stop the vehicle. Do not lock the inter-axle differential
while going down steep grades or traveling faster
Regional Haul (R05/10) Y53-6033 – 125 –