Troubleshooting Pump Problems - JLG Lull 1044C-54 II Series Service Manual

Troubleshooting Pump Problems

Problem
1. Excessive pump noise
2. Pump Overheating
3. System not developing
pressure
31200079
(Ref. Fig. 5-21) The hydraulic pump is located on the transmission towards
the back of the machine.The hydraulic pump used is a two-section gear
type, driven directly from the transmission power takeoff.
PUMP SPECIFICATIONS:
Type - Gear
Sections - Two
Manufacturer - Vickers
Model - G2020
GPM - 18 at 2500 RPM (Cover End - Pump 1)
GPM - 26 at 2500 RPM (Shaft End - Pump 2)
Probable Cause
A. Low oil level in the hydraulic
reservoir
B. Air in the system
C. Vacuum condition
D. Oil too thick
E. Cold weather
A. Internal leakage
B. Low fluid level
A. Relief valve open
B. Loss of fluid internally
(slippage)
Supply, Pressure, and Return Hydraulics
Solution
Fill reservoir to proper level with the recommended
hydraulic fluid. DO NOT overfill.
1. Operate hydraulic system until purged.
2. Check inlet (suction) lines and fittings for air
leaks.
1. Check inlet (suction) lines and fittings for
restrictions.
2. Check reservoir breather filter conditions.
Be certain correct type of oil is used for refilling or
adding to the system. Viscosity must be correct for
ambient temperatures.
Run hydraulic system until unit is warm to the
touch and noise disappears. Check oil viscosity.
Return vehicle to maintenance shop for evaluation
and repair.
Add oil to operating level.
Replace or repair the relief valve.
Return the vehicle to the maintenance shop for
repair of hydraulic system.
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