Navistar WorkStar Series, Operator'S Manual

Page: 158 / 258

Operation
Lowering the Lift Axles
With the lift axle system enabled, when the DOWN position of
the UP/DOWN switch is selected, air is vented from the lift bags,
thus causing the axle to be lowered. At the same time, air is
applied to the axle load bags through the air pressure regulator
for adjustment of the proper axle load carrying capacity. The
amount of air pressure applied to the load bags is monitored by
the air pressure gauge. The switch DOWN indicator will be lit
indicating that the axle is in the operational position. Refer to the
load capacity charts to determine the air pressure needed
for the desired load capacity for both axle designs.
Raising the Lift Axles
WARNING
On systems with self-steering lift axles, the axle
will automatically rise to the UP position any
time the transmission is shifted into reverse, and
back down when the transmission is shifted out
of reverse. Before backing up, check to see that
area behind vehicle is clear of people, animals
and objects. Use a spotter whenever possible
and always keep that person in sight. Failure to
do so may result in property damage, personal
injury, or death.
When the UP position of the UP/DOWN switch is selected, air
is vented from the axle load air bag and, at the same time,
pressurized air is routed to the lift bag, raising the axle.
For system with self-steering axles, when the transmission is
shifted into Reverse, +12 VDC is removed from the air solenoid,
venting air from the axle load air bag and supplying air to the
lift bag. This lifts the axle (s) regardless of the position of the
UP/DOWN switch.
Load Capacity Chart for 20,000 Pound Fixed Lift Axle
Mounting Height
Ground Axle
Load
9 in. 10 in. 11 in.
5,000 lbs 15 psi 15 psi 15 psi
10,000 lbs 36 psi 36 psi 36 psi
15,000 lbs 58 psi 58 psi 58 psi
20,000 lbs 79 psi 79 psi 79 psi
1. This table is approximate. To obtain an accurate load vs. air
pressure reading, it is necessary that the unit be calibrated over a
flat and accurate scale.
2. This table assumes 1500 lbs ground weight with 0 psi air
pressure.
Load Capacity Chart for 13,200 Pound Steerable Lift Axle
Mounting Height
Ground Axle
Load
10 in. 11 in. 12 in.
5,000 lbs 29 psi 31 psi 34 psi
6,000 lbs 37 psi 39 psi 43 psi
7,000 lbs 44 psi 47 psi 52 psi
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