LG956 Wheel Loader. Instruction - page 29
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z Check the clearance and wear condition of the pins and the bushes in every articulated point.
In addition, do the extra maintenance in the first 1000 hours as follows:
z Replace the hydraulic oil. And then replace once every 2000 hours.
3.6 Every 2000 Hours (Year) Service
Carry out the periodic maintenance of every 10, 50, 250, 500 and 1000 hours with this maintenance
operation at the same time.
z Check performance of the torque converter and gearbox, differentials of front and rear axles and
the wheel side reducers. Disassemble them for checking if necessary.
z Check the sealing performance of multi passage valve and hydraulic tank by measuring the
natural sedimentation volume of the cylinders fuel oil, and then check the system pressure.
z Check the welded seams of rim and other stress parts and adjust the deformation.
3.7 Alteration
The maintenance principles listed above are the normal requirements. The maintenance time should
be determined by the closer one between the two the maintenance schedules. If the working condition
is very severe, please shorten the maintenance cycle and increase the maintenance times according to
the real conditions.
3.8 Replace The Air-Storage Tank After 3 Years of Service
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CHAPTER V SYSTEM PRICIPLE
DIAGRAM
1 TRANMISSION SYSTEM
The transmission system includes the hydraulic torque converter, transmission box, transmission axle,
front and rear driving axle, wheel and others. The transmission system diagram is shown in the Figure
5-1.
Figure 5-1 Transmission System Principle Diagram
2 HYDRAULIC SYSTEM
2.1 Pilot Control and Load Sensing Hydraulic System
As shown in Figure 5-2, the hydraulic system includes the working equipment hydraulic system and
steering hydraulic system. The pilot control hydraulic system is composed of a work pump, pilot
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valve, multi-way valve, load select valve, lift arm cylinder, bucket cylinder, hydraulic pressure oil
tank and pipe attachments, which is mobile and flexible. The bucket unit includes dumping, neutral
and receiving bucket in three positions. The lift-arms unit controls four actions including floating,
lowering, neutral and lifting. The set pressure of the hydraulic system safety valve is 17MPa.
The steering hydraulic operating system employs load sensing hydraulic system. When steering, the
system prior to supply oil to steering hydraulic system, and the residual oil returns to the oil tank
through the radiator. The safety valve is set on the priority valve and the set pressure is 16MPa.
1- Work Pump 2-Bucket Cylinder 3-Lift Arm Cylinder 4- Multi-way Directional Valve
5- Priority Valve 6-Hydraulic Oil Tank 7-Pressure Select Valve 8-Hydraulic Oil Radiator
9-Double Units Pump 10-Priority Valve 11-Redirector 12-Steering Cylinder
Figure 5-2 Pilot Control and Load Sensing Hydraulic System Principle Diagram
2.2 Pilot Control and Flow Enlarge Hydraulic System
As shown in Figure 5-3, the pilot control hydraulic system is composed of a work pump, pilot valve,
multi-way valve, load select valve, lift arm cylinder, bucket cylinder, hydraulic pressure oil tank and
pipe attachments, which is mobile and flexible. The bucket unit includes dumping, neutral and
receiving bucket in three positions. The lift-arms unit controls four actions including floating,
lowering, neutral and lifting. The set pressure of the hydraulic system safety valve is 18~18.5MPa.
The overload pressure of the bucket large cavity is 20.5MPa while that of the small cavity is 12MPa.
The steering hydraulic system employs flow enlarge type full hydraulic hinged steering system. The
steering flow enlarge system is composed of steering pump, unloading valve, flow enlarge valve,
redirector, steering cylinder, hydraulic oil tank and pipe attachments.
The oil way classifies into pilot oil way and main oil way. The flow of pilot oil way controls the flow
of main oil way to remain the ratio between the flow change of steering cylinder to its flow be a
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certain value. Use low pressure small flow to control high pressure large flow in order to control the
steering system flexibly. The safety valve is set on the flow enlarge valve and the set pressure is
14MPa.
When the working pressure of working device hydraulic system is lower than 16Mpa, the hydraulic
oil of steering through the flow enlarge valve PF port and unload vale concourses with working
device hydraulic systems to utilize low pressure large flow working; When the working pressure of
working device hydraulic system is more than 16Mpa, the unload valve unloads the pressure, and
supply oil to the working device by working pump only to utilize high pressure small flow working.
1- Work Pump 2- Hydraulic Oil Tank 3- Pressure Select Valve 4-Double Units Pump
5-Flow Enlarge Pump 6-Steering Cylinder 7-Redirector 8- Priority Valve
9- Multi-way Directional Valve 10-Lift Arm Cylinder 11- Bucket Cylinder
Figure 5-3 Pilot Control and Flow Enlarge Hydraulic System Principle Diagram
3 BRAKE SYSTEM
Brake system is used when the machine decelerates, stops or for long-term parking on the level
ground or slight incline. The brake system of this machine is composed of a driving brake system and
parking brake system as shown in Figure 5-4 and 5-5.
