The hydraulic transmission system on wheel loaders mainly consists of working device hydraulic system, steering hydraulic system and variable speed variable speed hydraulic system. It has the advantages of compact structure, flexible operation, smooth operation, easy to operate and easy to operate. However, because the hydraulic system uses liquid as the medium of transmission power, it is easy to produce leakage. After a long running time, it is easy to overheat, work powerless, and damage the internal components.
Today, we mainly talk about the failure analysis of wheel loader hydraulic system and the solutions.
The cause of the failure of the hydraulic system of the carrier:
Faults usually appear as follows: Boom lifting and bucket turning weak.
There are four main reasons for the failure.
1. Low system pressure:
At the pressure point of the distribution valve, the measuring range is 25MPa. When the engine and hydraulic oil are in the normal working temperature and the engine speed is around 1800r/min, the valve is manipulated by the valve to turn the bucket to the end, and the pressure of the pressure gauge should be 17Mpa. If the value is below this value, check the safety valve to check whether the pilot valve spring is broken, the seal is good, the main valve core is dead and the damped hole is blocked. When there is no problem above, adjust the pressure adjusting screw to make the system pressure reach the normal value.
2. The internal leakage of the working gear pump:
The internal leakage of gear pump is shown as follows: when working noise is high and the engine speed is higher, the noise is greater; a large amount of copper scraps can be seen in the oil filter. The gear pump should be removed to detect the gear clearance (normal value is 0.100-0.140mm) gear meshing clearance (normal value 0.005~0.015mm), the radial clearance of the gear (normal value 0.100~0.200mm), and check the seal is good. If there is a difference or damage, it should be repaired or replaced.
3, distribution valve internal leakage:
The main causes of leakage in the distribution valve are: the main valve core of the total safety valve is jammed; the gap between the valve stem and the valve body is too large (normal clearance is 0.025~0.040mm); the stem or valve body is pulled; the seal is damaged.
4, the inner leakage of the jar or the cylinder of the bucket:
The piston of the boom cylinder or the rotary bucket cylinder is collected to the bottom, and the tubing cavities are removed, so that the rod cavity of the boom cylinder or the rotary bucket cylinder continues to be filled with oil. If there are more fluid vent (normal leakage of less than 30ml/min), the piston seal ring has been damaged and should be replaced, and the bucket can be filled with load, lift to the limit position, the arm control rod is placed in the middle, and the engine is extinguished, and the sinking speed of the arm is observed (normally <40mm/h); and then, the sinking speed of the arm is observed. The lever of the manipulator is placed in the upward position, if the speed of the sinking of the arm is obviously accelerated, the inner leakage occurs in the hydraulic cylinder; if the change of the sinking speed is not obvious, the inner leakage causes the distribution valve.
