LG936L Wheel Loader. Manual - part 25

Operation & Maintenance Manual──LG936L Wheel Loader 

 96

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. 

 

Operation & Maintenance Manual──LG936L Wheel Loader 

 97

3.8.4 Hydraulic System of Work Equipment 

No. 

Problems  

Possible Causes 

Remedy  

1 

1  Insufficient 

rising force of 
life-arms 

1  Over worn or damaged cylinders 
2  Over worn multi passage valve, 

excessive clearance between valve 
spool and valve block 

3  Oil leakage of oil lines 
4  Severe internal leakage of working 

pump 

5  Idle suction of working pump 
6  Low set pressure value of safety valves 
7  Clogged suction tube and filter 

1  Change the oil seals of cylinder
2  Change the distribution valve 
3  Find out the leaking points and 

repair 

4  Change the oil pump 
5  Check oil lines and remedy 
6  Regulate the system pressure to 

set value 

7  Clean the filter, strainer, and 

change oil 

2 

Insufficient force 
of the bucket, the 
bucket tend to 
lower down or 
float up 

1  Damaged seal ring of steering cylinder 

piston 

2  Over worn of multi passage valve, 

excessive clearance between valve 
spool and valve block 

3  Low set pressure value of safety valves 
4  Overload valve and oil complementary 

valve is blocked by dirt 

1  Change the oil seals 
2  Change multi passage valve 
3  Change the system pressure to 

its prescriptive value 

4  Disassemble and clean 

3 

Hydraulic oil 
mixing into 
gearbox 

Aged or broken oil seals of working pump 
or steering pump lead to the hydraulic oil 
leaking into the gearbox 

Change oil seals or change oil 
pump 

4 

Foam in hydraulic 
oil tank and harsh 
noise 

1  Suction oil line is damaged and air is 

sucked into oil lines 

2  Low oil level and large amount of air is 

sucked into oil lines 

1  Check the oil lines, remedy the 

leaking parts. Replace if 
necessary. 

2  Add hydraulic oil to specified 

level 

 

 

 

 

 

 

 

 

 

 

 

 

Operation & Maintenance Manual──LG936L Wheel Loader 

 98

3.8.5 Steering System 

No. Problems 

Possible 

Causes 

Remedy 

1 

Heavy steering 

1  Insufficient oil supply for working pump 

and steering pump 

2  Air in steering system 
3  Faulty steel-ball in check valve body of 

steering unit causes heavy steering and 
little pressure during either slow or quick 
turning of steering wheel 

4  Faulty of piloted valve 
5  Too low pressure of safety valve 

1  Check oil pump 
2  Discharge air from system and 

check the suction lines 

3  Check the valve. Clean if it is 

blocked by dirt 

4  Replace piloted valve 
5  Readjust the pressure to 

specified value 

2 

Increased 
steering turns 

1  Insufficient oil level in hydraulic reservoir 
2  Leakage in oil lines, damaged oil seals 
3  Internal leakage of steering cylinder 
4  Worn steering unit 
5  High viscosity of oil or wrong brand of oil 

1  Fill oil to specified level 
2  Change seals of oil circuits 
3  Change seals of hydraulic tanks 
4  Replace steering unit 
5  Change by the specified oil 

3 

Inflexible or 
failure of 
steering system 

1  Damaged spring plate of steering unit 
2  Cracked, broken or deformed centre pin 

and drive shaft 

3  Faulty dual overload valve 
4  Scuffed rotor and stator, scuffed valve 

spool, valve body and sleeve 

5  Faulty in steering pump or piloted valve 

1  Change the damaged spring 

plate 

2  Change the center pin or drive 

shaft 

3  Check and repair the 

bi-directional overload valve 

4  Disassemble, check, clean and 

assemble strictly or change parts

5  Change the damaged parts 

4 

Steering wheel 
can not reset 

1  No concentric steering column and valve 

spool 

2  Steering shaft axially locks the valve plug 
3  Large axial resistance of steering column 
4  Broken spring plate 

Phenomena: medium pressure drop 
increases or the relief of steering unit fails 
when steering wheel stops (wheel loader 
deflects from straight traveling line) 

Remove the problems according to 
the respective reasons. 

 

 

3.8.6 Engine 

Refer to 

Operation and Maintenance Manual 

of diesel engine for troubleshooting. 

 

 

Operation & Maintenance Manual──LG936L Wheel Loader 

 99

 

CHAPTER  

MAINTENANCE

Ⅳ

 

1 MAINTENANCE GUIDE 

Read following information carefully before carrying out maintenance and inspection. 

1.1 Attention to Maintenance and Inspection 

z  Perform the maintenance on hard and level ground. 
z  Lower the work equipment near the ground and level the bucket. 
z  Set all control levers (or handles) to the Neutral position. 
z  Press the parking brake switch. 
z  Put blocks in the front and back of wheels. 
z  Lock the front and rear frames with frame locking bars. 

1.2 Hanging Warning Tag 

z  Attach the warning tag near the starting switch before maintenance to prevent someone starting 

the engine during maintenance. 

1.3 Fitting preparation 

z  Use only parts specified by the manufacturer of the loaders wheel. 

1.4 Oil and Fuel preparation 

z  Use oil and fuel specified in this manual according to ambient temperature. 

1.5 Using the Prescriptive Oil and Fuel 

z  Keep containers of oil and fuel clean and use clean oil and fuel. 

1.6 Keep the Machine Clean 

z  Always keep the machine clean. Keep grease fittings, pipe joints and oil level gauges clean and 

prevent foreign materials entering. 

1.7 Pay Attention to the Refrigerant Water and Oil in High Temperature 

z  It is very dangerous to drain hot oil and refrigerant water or remove the filters immediately after 

the engine stops. Make sure the engine is cool. The temperature of the oil drained is appropriately