HYDRAULICS
8O-54
LIFT CIRCUIT TEST
Lift Circuit
1. Shut down the engine.
2. Install a 2000-psi (13790 kPa) pressure gauge
with a quick connect fitting on the quick fitting
located on the lift valve; see Figure 8O-4.
3. Set the parking brake, start the engine, and
advance the engine speed to full throttle.
4. Using the joystick, lift the reels completely.
5. While watching the pressure gauge place the joy-
stick in the raise position. As the lift cylinder dead-
ends the pressure gauge should read approxi-
mately 1500 psi (10,335 kPa).
Conclusion
• If the relief valve opens within range, relief valve and
lift circuit are not at fault.
• If the relief valve exceeds range, replace the relief
valve.
• If the relief valve does not reach range, the reel
(auxiliary) hydraulic pump may be at fault. Proceed
to with test.
6. Shut down the engine and remove the ignition
key.
7. Remove the hydraulic hoses from the lift cylinders
(Figure 8O-4) and plug the hoses. Cap the lift cyl-
inder ports.
8. While watching the pressure gauge place the joy-
stick in the raise position. As the lift cylinder dead-
ends the pressure gauge should read approxi-
mately 1500 psi (10,335 kPa).
Conclusion
• If the relief valve opens within range, a lift cylinder is
at fault. Isolate the cylinder by shutting down the
engine and removing the plugs from one lift cylinder
at a time and repeating Step 8.
• If the relief valve does not reach range, perform a
reel (auxiliary) hydraulic pump flow test.
9. Remove plugs and caps and connect hoses to the
lift cylinders.
Figure 8O-4. Lift Circuit Testing
CAUTION
The plugs inserted in the lift cylinder hoses must be
able to withstand the maximum lift cylinder pressure.
Quick Connect Fitting
Lift Cylinder Hoses
0 to 2000 psi
(0 to 13790 kPa)
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