CG958H Wheel Loader. Manual - part 17

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70

3. Dismounting and servicing of steering gear by untrained maintenance staff is strictly 

prohibited. 

4. Simultaneous hard steering by two people is strictly prohibited. 

 

CAUTION 

When replacing rubber tube assembly in steering gear, loader engine should be shut off first to 

release pressure and cool down hydraulic oil (to a safe degree) before the replacement is made. 

1.  Priority valve (Eaton VLE-150) 

 

 

 

 

a Structure and principle 

 

b Position of priority steering control valv 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 Excess joint, 2 O-ring, 3 Safety pressure controlled 
valve, 4 Nut, 5 Valve body, 6 O-ring,, 7 Screw cap, 8 
Pipe plug, 9 Valve core, 10 Pressure spring, 11 Oil plug 

,  

     

Hydraulic schematic diagram 

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71

IMPORTANT 

 

Dismounting and servicing of priority steering control valve by untrained maintenance staff is 

strictly prohibited. 

 

 

CAUTION 

 

When replacing rubber tube assembly in priority steering control valve, loader engine should 

be shut off first to release pressure and cool down hydraulic oil (to a safe degree) before the 

replacement is made. 

 

IMPORTANT 

Dismounting and servicing of steering cylinder by untrained maintenance staff is strictly 

prohibited. 

CAUTION 

When replacing rubber tube assembly in steering cylinder, loader engine should be shut off 

first to release pressure and cool down hydraulic oil (to a safe degree) before the replacement is 

made. 

5.

 Emergency steering

: 

Steering system features emergency steering function. When a sudden failure occurs to 

steering pump, etc., pressure in steering system drops quickly and the emergency steering is 

automatically started when the pressure drops to 0.6 Mpa (6kg).

 

 

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 60s 

Emergency steering power unit: model number: 11551-00. 

 

The ascending flow curve allows emergency steering system to have adequate steering power 

and velocity. Steering control components is able to turn from neutral position to the position of 

steering angle measured in B.3.2 (i.e. 38º/2=19º) in 6 seconds after the operation begins. Forward 

velocity should be kept at (10±2) km/h, and steering control force should not exceed 350N. 

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72

IV. Pressure relief of system: 

Turn off engine and then turn steering wheel leftward and 

rightward for several times to eliminate internal pressure of 

pipeline system. 

Hydraulic oil leakage in pipelines may cause accident and 

leads to personal injury or death. Leaking pipeline is damaged 

and should be replaced. When replacing pipeline, first 

eliminate (release) pressure and cool down hydraulic oil (to a 

safe degree) before the replacement is made. 

V. Lubrication of oil cylinder pin: 

Adopt BAKE automatic concentrated lubrication. 

VI. Troubleshooting of hydraulic steering system 

Failure Symptoms 

Causes 

Solutions 

Dirt on joint faces 

Check and clean joint 

faces 

Shaft sealer ring damaged 

Replace sealer ring 

Oil leakage 

Leakage on joint faces of 

parts 

Leakage at front cover 

Leakage at screws 

Insufficient tightening 

torque of screw 

Tighten screw 

Steering is heavy in fast 

turning and light in slow 

turning 

Insufficient oil supply 

Check pump and priority 

steering control valve 

Oil cylinder crawls with 

irregular noise and bubbles 

in oil 

Air in steering system 

Eliminate air in steering 

system and check pump 

inlet for leakage 

Heavy steering, and no 

steering cylinders do not 

work 

Manual steering check valve 

failure 

Check for existence of 

steel ball and jam by dirt

Oil cylinders do not work 

Leakage at FK overload 

valve or in cylinder 

Replace FK combination 

valve and check cylinder 

for internal leakage 

Light steering with zero load 

and heavy steering with 

heavy load 

FK safety valve leakage or 

safety valve spring failure 

Replace FK combination 

valve 

Heavy 

steering 

Heavy steering 

High hydraulic oil viscosity 

 

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73

No opposite rotation 

Spring leaf failure 

Replace spring leaf 

Marked increase of pressure 

runout, and even steering 

failure 

Bent or broken key, crack in 

universal driving shaft 

keyway 

Replace key or universal 

driving shaft 

Steering 

malfunction 

Opposite rotation or 

wagging of steering wheel 

immediately after steering 

Misplacement of universal 

driving shaft and rotor 

Reassemble 

No manual 

steering 

Cylinder piston reaches limit 

and no sense of steering 

dead end in power steering, 

steering cylinders do not 

work in manual steering 

Large radial or axial 

clearance in stator and rotor 

Replace stator and rotor 

Steering is 
normal in 
slow 
turning and 
heavy in 
fast turning 

Steering is normal in slow 
turning and heavy in fast 
turning 

(1). Insufficient oil supply 
from oil pump 
(2). Large pressure loss 
between priority valve and 
steering gear 
(3). Priority valve plug 
blocked 
(4). Air in control oil circuit 
between priority valve and 
steering gear 

(1). Repair or replace oil 
pump 
(2). Use a priority 
control spring with larger 
control pressure, or 
redesign pipeline with an 
externally controlled 
priority valve 
(3). Turn steering wheel 
to reach dead end and 
then keep turning to 
open steering safety 
valve for air elimination 

Irregular 
noise and 
bubbles in 
oil 

Irregular noise and bubbles 
in oil, intermittent working 
of cylinder in steering 

Air in steering system 

(1). Check oil level and 
add oil to oil tank 
(2). Check air intake 
pipeline for air leakage 
and repair 
(3). Eliminate air in 
steering system