Key hints: KOMATSU PC200-6 excavator work failure to troubleshooting: Komatsu PC200-6 full hydraulic crawler excavator sometimes can appear the whole machine work weakness, slow movement phenomenon, we analyze its main reason is the hydraulic system has been malfunction.
The PC200-6 type full hydraulic crawler excavator in Komatsu sometimes has the phenomenon of weak operation and slow movement. The main reason for our analysis is the failure of the hydraulic system.
1. main pump pressure is low
The PC200-6 type excavator adopts a double swash plate axial variable piston pump. Under normal conditions, the output pressure of the main pump is more than 30MPa. If the wear of the plunger and cylinder between the main pump and the cylinder body or the cylinder body is more than the standard (the clearance between the plunger and the cylinder should be less than 0.02mm, the contact area between the end of the cylinder and the flow plate should be less than 90%), the output pressure of the main pump will be low and the mechanical working device will appear. The inability of the whole machine to work.
2. main pump output flow control valve group has trouble
The output flow of the main pump varies with the power of the engine, with the power of the main pump and the engine to reach the best match and fully play the role of the engine. If the control valve group used to adjust the output flow of the main pump, such as the PLS feedback loop blockage, the LS valve spool card, the PC valve spool card, or the PC - EPC solenoid valve inner coil are burnt out, the main pump will always be in a state of constant flow. If the main pump has been in a low flow state, the machine will be weak and slow when it works.
Similarly, if the swashplate, servo piston and other parts of the main pump directly control the flow rate of the main pump are stuck, the output flow of the main pump will not change.
3. the control pressure of the pressure relief valve is low
Under normal circumstances, the pressure reducing valve can reduce the output oil pressure of the main pump and stabilize it at 3.3MPa to form oil pressure control. If the oil valve is too dirty, the cone valve spool of the relief valve will be closed, which will cause the output pressure of the pressure reducing valve to be less than 3.3MPa. At this time, no matter how the handle of the operation handle, the control oil pressure is always low, the movement of the main control valve of various working devices is small, so that the flow of the flow to the working device is also small, causing the whole machine to be weak.
The overflow pressure of the 4. main overflow valve is low
The main overflow valve limits the maximum pressure of the entire hydraulic system to 32.5MPa. For the high pressure exceeding this value, the main overflow valve will open the pressure relief to protect the system from damage. If a small hole in the main overflow valve core is blocked because of poor oil quality, the valve core is often open, or the set overflow pressure of the main overflow valve is low, the actual overflow pressure is low, that is, the pressure of the system is low.
5. discharge valve failure
When the driver starts the engine and puts the lever in neutral, the main pump outputs the hydraulic oil directly back to the fuel tank through the unloading valve, and the unloading pressure is 3MPa. If the valve core of the unloading valve is closed because the oil is too dirty, the output oil of the main pump will pass through the tank through the unloading valve when the machine is working, so that the system can not be made up of high pressure. Similarly, if the 0 type seal on the unloading valve used to block the PlS pressure oil and the tank is damaged, the hydraulic oil of the main pump will also flow back to the oil directly. Box.
6.LS bypass valve failure
The LS bypass valve can leak out a portion of the P15 pressure oil on the LS loop through two small holes on the valve body (slightly) to increase the softness of the machine operation. If the o - shaped seal on the valve body is damaged, the PL5 pressure oil will directly connect with the tank, which indirectly causes the unloading valve to open, causing the working device to move slowly and slowly.
In short, if the PC200 - 6 excavator can not work well, it can be largely attributed to the poor quality of hydraulic oil. Therefore, the key to avoid or reduce such faults is to replace the hydraulic oil filter on time (for every 500 h changes) and to monitor the hydraulic oil oil (viscosity, fluidity and without suspension, etc.).
