Troubleshooting - Hydraulic Problems - Doosan DX140R Shop Manual

Problem
Pressure at swing motor
inlet shows no increase,
and the swing motor is
making irregular noises.
Pressure at swing motor
inlet shown no increase, but
without irregular noises
from the swing motor.
Oil Leakage:
From drive shaft From
bolted connections or other
assembled surfaces.
Excess heat:
Gearbox casing becomes
excessively hot, with or
without irregular noise (s),
during operation.
TROUBLESHOOTING –
HYDRAULIC PROBLEMS
Problem
Attachment cylinders, swing
and travel motors are all
inoperable. Loud noises are
heard from main pump
assembly.
Attachment cylinders, swing
and travel motors are all
inoperable. No usual or loud
noises can be heard.
Sluggish performance of all
hydraulic functions –
attachment, swing and
travel.
Hydraulic System Troubleshooting, Testing and Adjustment
Possible Cause
Swing motor drive shaft damage.
Internal damage to gearbox drive
train.
Hydraulic pump or valve problem.
Oil seal damaged Assembly
compound (joint sealer) old and not
sealing, bolt not tight or flange
warped.
Low oil level.
Bearings or gears worn but not
completely inoperative.
Possible Cause
Main pump(s) malfunction.
Low oil level in hydraulic system.
Main pump inlet (oil supply) piping
or hose damaged.
Pilot pump malfunction.
Pilot cutoff solenoid stuck.
Pilot cutoff switch faulty.
Engine/pump flex coupling
damaged.
Main pump(s) damaged or worn.
Main relief valve pressure off.
Low oil level in hydraulic system.
Hydraulic reservoir intake strainer
clogged.
Pump inlet (supply side) piping or
hose allowing air into hydraulic
system.
Remedy
Replace swing motor.
Repair/Replace broken or faulty
assemblies.
Troubleshoot hydraulic system.
Replace oil seal Disassemble and check
mating surfaces. Reapply Loctite; torque
bolts to specifications.
Replace oil; refill to specified level.
Repair or replace gearbox.
Remedy
Repair or replace.
Refill.
Repair or replace.
Repair or replace.
Repair or replace.
Repair or replace.
Replace flex coupling.
Repair or replace.
Readjust pressure.
Refill.
Clean.
Tighten connection.
SP001942
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