operators_manual

under heavy loads or rough terrain as well
as for over the road hauling.
The Low Range provides maximum torque
for hauling heavy loads or traveling over
rough terrain. The High Range is a faster
ratio for highway speeds and general over
the road conditions. A switch on the
accessory switch panel controls the Dual
Range Rear Axle. You will notice that the
switch has a guard to protect you from
activating it accidentally. Always park your
vehicle with the range selector in LOW.
Important tips on operating a Dual Range
Axle with Interaxle Differential:
• Shift the axle with the inter-axle
differential in the unlocked position
only.
• When you are driving with poor
traction, lock the differential. When
you have the differential locked,
drive with the axle in LOW range
only.
• When you are driving on a surface
with good traction, keep the
interaxle differential unlocked. You
can drive with the axle in the LOW
or HIGH range.
• Always UNLOCK the inter-axle
differential before shifting the axle
speed range.
WARNING
Never shift the axle when moving
downhill. Engine driveline disengage-
ment may occur, eliminating engine re-
tardation and allowing the wheels to
spin faster than the current speed of
the engine. This may require severe
braking to slow the vehicle down and
can result in an accident. Failure to
comply may result in death, personal
injury, equipment or property damage.
CAUTION
If you shift the axle range with the in-
ter-axle differential in LOCK, you could
seriously damage the axles. Never
shift the axle range with the differential
locked.
Proper shifting of the axle depends on the
synchronization of engine/driveline and
wheel speed. When you shift the axle, the
connection between the engine and wheels
is momentarily disengaged while the
gearing is synchronized. Normally when
the axle is shifted the speed of the engine,
axle, and wheels adjust, allowing for proper
gear engagement.
When going downhill the wheels will not
slow down, but will tend to speed up, which
makes gear synchronization almost
impossible. As a result, the axle is neither
in HIGH nor LOW range and all engine/
driveline retardation is lost. Without engine
retardation it is more difficult to slow the
vehicle down and greater stress is put on
the brake system.
CAUTION
To avoid damaging your vehicle shift
the axle at slower travel speeds until
you are used to driving with a dual
range axle.
How to Operate Two Speed Axle -
Low to High
These steps should be used if operating a
2 speed axle in LOW range on rough
DRIVING - Axle and Suspension
Y53-6047-2HEN (03/18) 157
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