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®
The HYDRAIR
II suspensions are hydro-pneumatic
components containing oil and nitrogen gas. The oil
and gas in the four suspensions carry the gross truck
weight less wheels, spindles and final drive assem-
bly.
The front suspension cylinders consist of two basic
components; a suspension housing attached to the
truck frame and a suspension rod attached to the
front spindle. Check valves and orifice dampening
holes control suspension travel to provide good ride
qualities on haul roads under loaded and empty con-
ditions. The front suspension rods also act as king-
pins for steering the truck.
®
The HYDRAIR
II suspension cylinder requires only
normal care when handling as a unit. However, after
being disassembled these parts must be handled
carefully to prevent damage to the machined sur-
faces. Surfaces are machined to extremely close tol-
erances and are precisely fitted. All parts must be
completely clean during assembly.
Removal
1. Park unloaded truck on hard level surface.
Block wheels and apply parking brake. Remove
front wheel and tire according to Removal
instructions in Section G, Front Tire and Rim.
Remove front wheel hub and spindle as cov-
ered in Section G.
2. Remove boot clamp and boot from around sus-
pension. Disconnect pressure sensor.
H02026
FRONT SUSPENSION
3. Discharge nitrogen pressure from suspension
by removing cap from charging valve (5, Figure
2-1). Turn the charging valve swivel nut (small
hex) (3, Figure 2-2) counterclockwise 3 full
turns to unseat valve seal (DO NOT turn more
than three turns). DO NOT TURN LARGE HEX
(4) (see DANGER below). Wearing face mask
or goggles, depress valve stem until all nitrogen
pressure has been relieved.
Make certain only the swivel nut (3) turns. Turn-
ing the complete charging valve assembly may
result in the valve assembly being forced out of
the suspension by the gas pressure inside.
1. Cap Structure
2. Sensor Port Plug
3. Charging Valve Guard
Front Suspensions
FIGURE 2-1. SUSPENSION CAP
4. Vent Plug
5. Nitrogen Charging
Valve
H2-3
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