How to repair the hydraulic system of Komatsu excavator？

First, the engine power is sufficient, the operation is normal, and the machine speed is slow, the excavation is weak.

1. The hydraulic pump of the excavator is a plunger variable pump, which works for a certain period of time. The original parts in the hydraulic pump such as (cylinder, plunger, distribution plate, rocking, etc.) inevitably produce excessive wear, resulting in a large number of internal leaks, various parameters. The data is not coordinated, resulting in insufficient flow of oil, too high temperature, slow speed, and can not establish high pressure, so the movement is slow and excavating. For such problems, the hydraulic pump must be removed and sent to the commissioning department of the company to test the hydraulic pump, confirm the problem of the excavator, replace the accessories that cannot be used, repair the accessories that can be used, and reassemble the hydraulic pump. After that, debug the test bench and match each series of soft parameters (such as pressure, flow, torque, power, etc.).

2. The excavator also has an important hydraulic original multi-way distribution valve with a main safety valve, a secondary valve, a jet valve, a charge valve and the like. If the pressure set by these safety valves is less than the standard pressure (the standard pressure of the EX200-5 main safety valve is 320kg, and the current pressure is only 230kg), the excavation is weak. Also, if the gap between the valve stem and the valve hole is too large due to wear and the valve stem is not fully returned, the flow rate is insufficient and the speed is slow. For such problems, the multi-way distribution valve must be removed, sent to the company and directly on the commissioning station for commissioning, reset the pressure of all safety valves, and eliminate the gap between the valve stem and the valve hole.

3. The hydraulic pump on the excavator is equipped with a pilot gear pump. The pump mainly participates in the variable of the hydraulic pump and opens the valve stem of the multi-way distribution valve as a pilot oil to make it reverse. If the gear pump is excessively worn, it cannot be established. A certain pressure or insufficient pressure set by the safety valve on the gear pump will cause the hydraulic pump to always be in a low flow state, and the valve stem cannot be completely reversed. This will result in insufficient flow, slow movement, insufficient pressure, and excavation weakness. In this type of situation, simply replace the pilot gear pump or reset the pilot safety valve.

Second, everything is normal when the machine is cold, the action is slow when the heat engine is running, and the excavation is weak.

The problem of this situation indicates that the hydraulic pump is not overhauled, and the internal parts of the hydraulic pump are seriously worn. If it continues to be used, it may cause serious damage to the hydraulic pump parts. All internal wear parts need to be processed or replaced, and then re-assembled and then commissioned on the test bench to restore the standard condition of the hydraulic pump.

Third, the engine power is enough, but there is a boring car (brake) phenomenon

The hydraulic pump itself also has a certain power. If the power of the hydraulic pump is greater than the power of the engine, there will be a boring phenomenon. This requires the test and debugging of the hydraulic pump on the test bench, and the power of the hydraulic pump can be reduced to 95% of the engine power.

Fourth, walking and deviation, while the movement of one handle is not ideal

The hydraulic pump is divided into front and rear pumps or left and right pumps. The running deviation indicates that one pump is faulty. The simplest way to judge is to remove the two high pressure oil pipes of the hydraulic pump and adjust them. If the original slow walking is faster, faster. Walking slows down, which means that there is a pump failure. For such problems, just remove the hydraulic pump, process or replace the accessories in one pump, and then debug on the test bench. Only the handle is not ideal.