Service Manual User Manual

Hydraulic System
9-65
Figure 9– 50. Unloader valve detail.
Unloader Valve Legend
1. Unloader Valve (includes items 2 through 8)
2. Cap
3. O-Ring
4. Spool Spring
5. Tube Spacer
6. Spool
7. Valve Housing
8. Relief Valve Assembly
Preset at 3500 psi ± 100 psi (241 bar ± 7 bar)
f. Unloader Valve Installation
1. Secure the unloader valve to the vehicle frame near
the transmission (Fig. 9– 49) with two 5/16" SAE
washers, two 5/16" lockwashers and two 5/16-18 x 3-
1/4" hex-head capscrews. Torque the capscrews to
18 lb/ft (24 Nm).
2. Connect the hydraulic lines to their appropriate ports
on the unloader valve.
3. Check the routing of all hoses, wiring and tubing for
sharp bends or interference with any rotating
members. All tube and hose clamps must be tight.
4. Start the engine and run at approximately one-third
to one-half throttle for approximately one minute
without moving the vehicle or operating any hydraulic
functions.
5. Inspect for leaks and check all fluid levels. The
hydraulic reservoir oil level must be visible in the sight
gage.
Note: Check for leaks and tighten fittings or repair as
required before continuing. Wipe up any spilled hydraulic
fluid.
g. Unloader Valve Pressure Check Test
Attach a 4000 psi (276 bar) gauge to the unloader valve
inlet port. Monitor the outlet pressure at the unloader
valve. It must provide 250 to 350 psi (17,25 to 24,15 bar)
within moments after starting the engine. Failure to
achieve this pressure means that the unloader valve is
not properly functioning.
1
2
3
4
5
6
7
8
Torque to Maximum 20 lb/ft.
(27 Nm)
PS0510
WARNING: Avoid prolonged engine operation
in closed areas with inadequate ventilation.
Failure to properly ventilate exhaust fumes can
result in death or severe personal injury.
Model 3606 • Origin 10/99