SECTION 3 - TROUBLESHOOTING
3-8
– JLG Sizzor –
3120826
Table 3-4. Hydraulic System Troubleshooting
TROUBLE
PROBABLE CAUSE
REMEDY
Hydraulic pump noisy
Air entering system through broken line or fitting
Repair or replace line or fitting
Air bubbles in oil
Replenish oil as required
Faulty pump coupler
Replace coupler
Defective pump bearing
Repair or replace pump
Oil filter(s) dirty
Clean and/or replace filter(s) as necessary
Pump cavitating (Vacuum in pump due to oil star-
vation
Restricted suction line
Clean, repair, or replace line
OIl in reserve low
Replenish oil to proper level
Restricted reservoir air vent
Clean vent
Oil viscosity to high
Drain system and replace with recommended oil
(Refer to hydraulic oils)
Leak in suction line or manifold
Repair or replace line or manifold as necessary
System overheating
Oil viscosity too high
Drain system and replace with recommended oil
(Refer to hydraulic oils)
Restricted or blocked hydraulic line
Repair or replace line
Machine overloaded
Check weight in platform
Main relief valve set too high
Reset valve as required
Hydraulic system oil low
Replenish oil as necessary
Pump not delivering oil
Restricted suction line
Clean repair or replace line
Air entering system through broken line or fitting
(suction side)
Replace or repair line or fitting
Oil level too low
Replenish oil to proper level
Plugged strainer in tank
Clean strainer
Pump coupling defective
Replace pump coupling
Broken pump drive shaft
Repair or replace pump
System pressure too low
Main relief valve set too low
Reset valve as required
Main relief valve stuck in open position
Clean, repair or replace valve (Check system oil for
contamination)
Hydraulic pump not functioning properly
Repair or replace pump
Leak in component, line or fitting
Repair or replace component, line or fitting
Scored valve spool; Scored cylinder
Replace valve; Replace cylinder
System(s) operate erratically
Sticking or binding valve spools, piston rod, etc
Clean, repair or replace components as required
Hydraulic oil not a t optimum operating tempera-
ture
Allow oil sufficient time to warm up
Pump drive slipping
Repair or replace drive
Summary of Contents for 25RTS
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Page 52: ...SECTION 2 PROCEDURES 2 36 JLG Sizzor 3120826 Figure 2 27 Drive Torque Hub 2WD 4WD Rear...
Page 56: ...SECTION 2 PROCEDURES 2 40 JLG Sizzor 3120826 Figure 2 28 Drive Torque Hub Brake 4WD Front...
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