Trouble Shooting - JLG 1850SJ Service And Maintenance Manual

Trouble Shooting

Low or No Flow From Gear Pump
Item
1. Check oil level in reservoir.
2. Check input spline condition.
3. Check pressure at pump inlet. Recommended inlet pres-
sure: 0.8 to 3.0 bar absolute. 0.6 Minimum at cold start.
4. Check condition of gear faces and bearing blocks.
5. Check bushings.
Excessive Noise
Item
1. Check oil level in reservoir.
2. Check inlet line for leaks.
3. Check pressure at pump inlet. Recommended inlet pres-
sure: 0.8 to 3.0 bar absolute. 0.6 Minimum at cold start.
External Leakage
Item
1. Check for pinched o-rings or backup ring seal.
2. Check pressure seals.
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SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
Table 5-43. Troubleshooting
Description
Description Insufficient oil to supply gear pump.
Input shaft broken or stripped.
Clogged suction filter or inlet screen.
Scored bearing block and gear faces will reduce pump effi-
ciency.
Overpressure of gear pump will cause idler gear bushing to
fail.
Description
Excessive air will cause cavitation sound.
Excessive air will cause cavitation sound.
Lower than normal inlet pressure causes excessive pump
noise.
Description
Pinched seal will allow leakage.
Damage to pressure seals is typically caused by reduced
stack-up in the pump assembly. This may be due to under-
torqued assembly fasteners, or more commonly is attrib-
uted to excessive wear on the bearing blocks. Reduced stack-
up will affect seal efficiency possibly to the point of seal
extrusion.
Action
Fill reservoir to proper level.
Repair or replace gear pump.
Replace filter or clean suction screen.
Repair or replace gear pump.
Repair or replace gear pump.
Action
Fill reservoir to proper level .
Repair inlet line.
Return inlet pressure to recommended levels.
Action
Replace pinched seal.
Inspect condition of bearing blocks. If they are found to be
worn, repair or replace the pump.
If bearing blocks are not worn, replace pressure seals and re-
torque pump assembly fasteners.
5-169