Operation & Maintenance Manual
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LG968 /969Wheel Loader
86
3.8.3 Brake System
No.
Problems
Possible Causes
Remedy
1
Insufficient
brake force
1
Oil leakage of pliers pump
2
Air in brake hydraulic lines
3
Low brake air pressure
4
Over worn leather cup of booster pump
5
Oil leakage from hub to brake plates
6
Worn brake plates
1
Change rectangular sealing ring of
pump
2
Bleed the air out
3
Check the sealing performance of
air compressor, control valve,
storage tank and lines.
4
Change the leather cup
5
Check or replace the seal of hub
6
Change brake plates
2
Failure to release
the brake
normally
1
Wrong position of brake valve spool,
locked piston rod, damaged or faulty
reset spring
2
Improper operation of booster
3
Pliers piston can’t reset
1
Refer to problem 2
2
Check the booster pump
3
Check or replace the rectangular
seal ring
3
Pressure in air
storage tank
drops quickly
after shutting
down (pressure
drop is over 0.1
MPa in 30 min)
1
Inlet valve of foot brake valve is
clogged by dirt even damage
2
Loose pipe fitting or broken pipes
3
Poor sealing performance of check valve
in combination valve of oil-water
separator
1
Brake for continuous several times
to blow the dirt off or change valve
2
Tighten the pipe fitting or change
brake pipes
3
Find out the reasons for sealing
failure and change parts if
necessary
4
Slow rise of
pressure reading
in the brake
gauge
1
Loose pipe fitting
2
Abnormal work of air compressor
3
Inlet valve or diaphragm of brake valve
is not sealed
4
The bleed hole of pressure controlled
valve is clogged or the diaphragm of
check valve leaks air.
1
Tighten the fitting
2
Check air compressor
3
Check and clean the inner parts of
brake valve, find out the unsealed
parts then repair
4
Clean air bleed hole, find out the
unsealed reasons of retaining valve
and diaphragm then repair.
