The most comprehensive knowledge of hydraulic system introduction of XCMG wheel loader

November 29 16:46 2021

The hydraulic system of XCMG wheel loader is a transmission form that uses the pressure energy of the liquid for energy transmission, conversion and control. It is mainly composed of the following aspects:

1. Power components: such as hydraulic pumps, which convert the mechanical energy of the prime mover into hydraulic energy

2. Actuating elements: such as oil cylinders, motors, etc., which convert hydraulic energy into mechanical energy

3. Control elements: various control valves to control and adjust the pressure, flow and direction of the liquid in the system

4. Auxiliary components: such as fuel tank, oil filter, pipeline, joint, oil diffuser, etc.

5. Working medium: hydraulic oil is the carrier of power transmission

The hydraulic system of the loader is mainly divided into the following parts: working system, steering system, some of which are G series

The loader also has a pilot system and a braking system.

1. Working hydraulic system

The function of the loader’s working hydraulic system is to control the movements of the boom and bucket. It is mainly composed of working pump, distribution valve, bucket cylinder, boom cylinder, oil tank, oil filter, pipeline, etc. The working system principle of the LW500FN wheel loader is the same as that of the LW300FN wheel loader, except that the specifications and models of the components of XCMG parts are different.

2. Brief introduction of main components

1. Working pump

Most of the pumps used on loaders are external gear pumps.

Rotation direction: viewed from the direction of the shaft end,

Clockwise rotation is right rotation,

Counterclockwise rotation is left-handed

2. Cylinder

The boom cylinder, wheel loader bucket cylinder, and steering cylinder to be introduced later in the loader are all piston-type single-rod double-acting hydraulic cylinders.

3. Distribution valve

The distribution valve is also called a multi-way reversing valve, which is mainly composed of three parts: the bucket reversing valve, the boom reversing valve, and the safety valve. The two reversing valves are connected in series and parallel oil circuits, and the movement direction of the oil cylinder is controlled by changing the flow direction of the oil. The built-in safety valve sets the maximum working pressure of the system.

4. Pipeline

The threaded connection between the hose and the joint was mainly Type A and Type D, with only one seal. Last year, we took the lead in adopting the current internationally popular 24°taper 0-ring double sealing structure in all products, which can effectively improve the leakage problem of the joint surface.

5. Fuel tank

The function of the oil tank is to store oil, dissipate heat, precipitate impurities, and escape the air that has penetrated into the oil. The 30 series loader uses a patented siphon self-sealing high-mounted fuel tank, and only a small amount of oil in the oil-absorbing steel pipe can be discharged during vehicle maintenance.

It is a pressurized fuel tank, which is realized by adopting PAF series pre-pressure air filter. The self-priming ability of the pump is improved, and the service life of the pump is prolonged.

Three, steering hydraulic system

The role of the steering system is to control the direction of travel of the loader. The loader produced by our company uses articulated steering. The steering hydraulic system is mainly divided into the following three forms:

1. Steering system with monostable valve

This system is the earliest fully hydraulic steering system adopted, mainly composed of steering pump, monostable valve, steering gear, valve block, steering cylinder, oil filter, pipeline, etc., and some are also equipped with hydraulic oil radiator. LW500FN steering system ZL50GN loader also adopts different specifications and models of the system components.

4. Brief introduction of main components:

(1) Steering gear

It uses a full hydraulic steering gear, which is mainly composed of a follow-up valve, a metering motor and a feedback mechanism

(2) Valve block

The valve block is mainly composed of a one-way valve, a safety valve, an overload valve and an oil supplement valve. It is connected between the steering pump and the steering gear, and is generally directly installed on the valve body flange of the steering gear.

(3) Monostable valve

The monostable valve guarantees the stable flow required by the steering gear to meet the steering requirements of the whole machine when the fuel supply of the oil pump and the system load change.

Five, other

1. The steering pump is also a gear pump, with the same structure and working principle as the working pump; the structure and working principle of the steering cylinder is the same as the boom cylinder and the bucket cylinder.

2. Load sensing full hydraulic steering system

The difference between this system and the above systems is: the priority valve is used instead of the monostable valve, and the steering gear adopts the TLF series coaxial flow amplifying steering gear.

The characteristic of this system is that it can distribute flow to it first according to the requirements of the steering oil circuit; and the remaining flow is merged into the working hydraulic system, which can reduce the displacement of the working pump.

3. Flow amplification steering system

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