Peterbilt Model 320 Operator's Manual after 8-07 - Peterbilt Motors ...

Dual Range (Two Speed) Axles
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
or cause axle damage—you could be injured.
Switch to LOCK only when the wheels
are not spinning.
• Do not operate the vehicle on dry pavement
with the differential locked; it could lead to
an injury accident. 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.
• Do not use the differential lock during downhill
operation 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 not turn
as quickly and more steering effort will be required,
which can cause an injury accident.
To reduce load on the drive train, ease up on the throttle
pedal whenever you shift into LOCK or UNLOCK.
PART 7: STARTING & OPERATING THE VEHICLE
Dual Range (Two Speed) Axles
If you have this option, dual range axles provide two rear
axle ratios for operating under heavy loads or off-highway
as well as for over the road trucking. The Low range provides
maximum torque for off-road work. The High range is
a faster ratio for highway speeds and conditions. A switch
on your instrument panel controls this function. You will
notice that it has a guard to protect you from activating it
accidentally.
0005
Range Selector
– 82 – Y53-6015 R(08/07)