Operation & Maintenance Manual──LG958L/LG959 Wheel Loader
97
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 as damaged
2 Loose pipe fitting or broken pipes
3 Poor sealing performance of check valve
in combination valve of oil-water
separator
1 Brake continuously 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.