What do you know about the hydraulic system of Wheel Loaders?

Wheel Loader is very helpful in engineering construction and the  loader Hydraulic System is a key part of it. How much do you know about the loader Hydraulic System. Here is some knowledge for you. 

First is the working principle of the loader Hydraulic System. 

Hydraulic transmission system includes working device and steering system. The working device system includes the working circuit of the moving arm lifting hydraulic cylinder and the working circuit of the bucket hydraulic cylinder, which constitute a series-parallel circuit. When the bucket hydraulic cylinder directional valve 3-leaves the median, moving arm lift hydraulic cylinder directional valve 11-is cut off. In order to lift the hydraulic cylinder with the moving arm, the directional valve 3 of the bucket hydraulic cylinder must be returned to the center. Therefore, the compound action of the moving arm and the bucket can not be carried out. So the thrust of each hydraulic cylinder is large, which is the form of hydraulic system widely used in the transfer machine. According to the operation requirements of the loader, the hydraulic transmission system should complete the following working cycle: the bucket flipped, raised (loaded), lifted, locked (transferred), tilted (unloaded) the bucket forward, tilted (unloaded) the moving arm. 

Next let’s introduce the causes of common faults in hydraulic system of wheel loader.

1.the bucket is weak and easy to fall off  

If only the bucket is easy to fall off the bucket or float up, but the arm lift is normal, the failure is not in the working gear pump, but in the rotating bucket cylinder in the distribution valve and the rotating bucket cylinder. And most of them are caused by the failure of the one-way valve on the piston of the bucket cylinder, the connection between the upper and lower cavities of the hydraulic cylinder, or the breakage of the oil seal on the piston of the bucket cylinder. If the clearance between the bucket slip valve and the valve body exceeds 0.035 mm, the leakage Will be too large and the pressure will not be enough, which will also cause this failure.

2.The moving arm is powerless or too slow to lift. 

If only the moving arm is powerless and the bucket will not fall off, it is not necessary to check the working pump. The fault only occurs in the arm joystick matching part of the working distribution valve, or due to the breakage of the piston oil seal of the moving arm cylinder.

3.Oil rush out of the steering wheel or from the middle of the steering gear casing

If the skeleton oil seal installed in the steering valve is broken and the oil will pop up the steering rod.

The third part is analysis of the overhearing hydraulic system of Wheel Loader.The high oil temperature of the hydraulic system of loader is mainly caused by the power loss of the system itself. The heating source is mainly from the power loss of the power system (pump), the leakage of the actuator (hydraulic motor, hydraulic cylinder) and the pipeline, the local pressure loss and the pressure loss of the hydraulic valve.