September 2016
Service and Repair Manual
Manifolds
Part No. 1272222
GS-84 • GS-90
83
7-6 Valve Adjus tments - F unc tion M anif ol d
7-6
Valve Adjustments -
Function Manifold
How t o Adj ust t he Sy stem Reli ef Valve
How to Adjust the System Relief
Valve
Note: Perform this procedure with a minimum
hydraulic oil temperature of 32°F / 0°C and a
maximum hydraulic oil temperature of 120°F /
48°C.
Note: Be sure that the hydraulic oil level is between
the full and add marks on the oil level indicator.
Note: Refer to Function Manifold Component list to
locate the system relief valve.
1
Models with outriggers:
Deploy the
outriggers and level the machine.
Models without outriggers:
Chock both
sides of the wheels at the steer end of the
machine.
2
Locate the system relief valve on the function
manifold.
3
Connect a 0 to 5000 psi / 0 to 350 bar
pressure gauge to the test port on the function
manifold.
4
Remove the platform controls from the
platform.
Note: Perform this test from the ground with the
platform controls. Do not stand in the platform.
5
Determine the test weight for your machine.
Refer to the specifications below.
Rated work load at full height, maximum
GS-3384 and GS-3390
2500 lbs
1135 kg
GS-4390
(most models - refer to capacity indicator
decal)
1500 lbs
680 kg
GS-4390
(some models - refer to capacity indicator
decal)
1800 lbs
816 kg
GS-5390
1500 lbs
680 kg
6
Using a suitable lifting device, place the test
weight, determined in step 5, at the center of
the platform floor. Secure the weight to the
platform.
7
Turn the key switch to platform control and pull
out the red Emergency Stop button to the on
position at both the ground and platform
controls. Start the engine.
8
Press and hold the lift function enable button.
9
Activate the platform up function and fully
raise the platform while observing the
pressure reading on the pressure gauge.
Result: The hydraulic pressure should not
exceed 3500 psi / 241 bar.
Result: The platform should lift and fully raise.
Proceed to step 13.
Result: The platform does not fully raise OR
raises too easily. Proceed to step 10.
Component damage hazard. Do
not continue to operate the
machine if the hydraulic pump is
cavitating.
10 Turn the machine off. Hold the system relief
valve with a wrench and remove the cap.
Summary of Contents for GS-3384
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