JLG 740A, Service And Maintenance Manual

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SECTION 5 - HYDRAULICS
3121160 – JLG Lift – 5-23
Initial start-up procedures
Follow this procedure when starting-up a new pump or
when the pump has been removed.
1. Install the pump on the engine. Ensure the pump
shaft is properly aligned.
INCORRECT SHAFT ALIGNMENT MAY RESULT IN DAMAGE TO
DRIVE SHAFT, BEARINGS, OR SEAL WHICH CAN CAUSE EXTER-
NAL OIL LEAKAGE.
2. Fill the main pump housing with clean hydraulic
fluid. Pour filtered oil directly into the upper most
case drain port.
3. Fill the inlet line leading from the pump to the reser-
voir. Check the inlet line for properly tightened fit-
tings and be certain it is free of restrictions and air
leaks.
4. To ensure the pump stays filled with oil, install the
case drain line in the upper most case drain port.
5. Install a gauge at port M2 to monitor system pres-
sure during start up.
6. While watching the pressure gauge installed at M2,
jog the engine or run at the lowest possible speed
until system pressure builds to normal levels (mini-
mum 160psi [11 bar]). Once system pressure is
established, increase to full operating speed. If sys-
tem pressure is not maintained, shutdown the
engine, determine cause, and take corrective action.
Refer to Troubleshooting.
7. Operate the hydraulic system for at least fifteen min-
utes under light load conditions.
8. Check and adjust control settings as necessary after
installation. Refer to Adjustments.
9. Shut down the engine and remove the pressure
gauge. Replace plug at port M2.
10. Check the fluid level in the reservoir; add clean fil-
tered fluid if necessary. The pump is now ready for
operation.
Troubleshooting
Table 5-6. Excessive Noise and/ or Vibration
Item Description Action
Check fluid level in reservoir. Insufficient hydraulic fluid will cause cavitation. Fill the reservoir to proper level.
Check for air in system. Air in system will cause noisy, erratic control. Purge air and tighten fittings. Check inlet for
leaks.
Check pump inlet pressure / vacuum. Improper inlet conditions will cause erratic behav-
ior and low output flow. Correct pump inlet pressure / vacuum conditions.
Refer to Hydraulic parameters.
Inspect shaft couplings. A loose or incorrect shaft coupling will cause
excessive noise and/or vibration. Repair or replace coupling and ensure that cor-
rect coupling is being used.
Check shaft alignment. Misaligned shafts will create excessive noise and/
or vibration. Correct shaft misalignment.
Hydraulic fluid viscosity above acceptable limits. Hydraulic fluid viscosity above acceptable limits
or low fluid temperature will not allow the pump to
fill or control to operate properly. Allow system to warm up before operation or use
fluid with the appropriate viscosity grade for
expected operating temperatures.