1. Features of the rotary hydraulic circuit
1.U-type median slide valve function
Due to the large rotation inertia of the rotary mechanism, in order to prevent the rotary driving oil from generating excessive peak pressure, the reversal valve generally exercises the U-type median slide valve function, forming two parallel sealing tapes, so the slide valve is formed in the working state. The impact of wear on leaks is larger than other types of spools.
2.m to the replenishment limit circuit
In order to avoid the inertial rotation of the bus, the low-voltage side produces a higher vacuum, thereby precipitating the gas in hydraulic oil, and there is a filling valve on the two working oils to ensure that the loop work is stable, because the two working oil road is completely symmetrical, so There are two plug-in pilot limit valve to limit the highest working pressure of the two roads.
2. Rotation is weak
The reason for hydraulic faults should be analyzed from the entire system, causing excavators to turn weakness.
The wear of the R pump motor and the reverse valve, too large, the return mechanism is too large and the servo manipulation is too low, but the most likely cause is as follows:
1. Filling valve wear
Since the fuel valve is often closed, the valve seat valve is generated between the valve seat valve, which is extruded deformation and wear. It is similar to the valve tapered surface of the engine, and is mainly worn by the wear of the valve heart, and the valve core valve after wear. The sealing of the back path is lowered (i.e., the driving state) is lowered, and the working pressure oil leaks from the fuel valve, which causes the rotation and weakness, and can not even be rotated.
2. Pressure valve damping hole clogging
Generally, the modulation pressure of the turning oil road is relatively low in the system, mainly related to the rated pressure of the hydraulic motor, and is much lower than the main pump rated pressure, so the restriction valve of the rotary oil path is often opened. The regular valve is often opened, and on the one hand, the wear of the valve core valve is caused, and the impurities in the oil fluid can cause the grouse of the valve-thyed bore. After the damping hole is blocked, the opening pressure of the restriction valve is completely determined by the preload of the main valve heart return spring. The preload can only satisfy the friction and hydraulic force of overcoming the valve heart, and cannot drive the rotary motor.
3, troubleshooting
Trouble-inspection
First check the working conditions of the hydraulic main pump. On the full speed of the boom, observe the degree of load of the engine, mainly determined according to the sound of the engine and the color of the exhaust gas. If the load level can reach 2/3 of the rated power, the main pump is working properly. The retransmission device, such as the degree of engine loads, and the rotation speed is slow, and it is not possible to rotate, it is possible to initially determine the failure of the filling valve and the limit valve.
2. Troubleshooting
Removing the tonic valve and the pressure pressure valve, such as the amount of the fuel valve valve core wear <0.3mm, can use the outer round grinding machine with the outer grinding machine, can also use a fine blade in the drill machine or the lathe. polishing. When assembling, the appropriate gasket can be matched on one end of the valve spring spring as needed. Such as wear is> 0.3mm, the replacement valve is required. The restricted valve mainly read the wear of the pilot valve, and the emergency excavator can also be used to repair the method, and if necessary, replace it. The restriction valve must be used to check if the damping hole is smooth with a light transmissive method. If it is not smooth, it should be used to use compressed air. When assembling, such as the on-site non-pressure sensing device, the adjustment bolt can be adjusted to 1 to 2 buckles in the lock nut. After assembly, according to the operation, it is appropriately adjusted. ,
According to the grinding conditions of the valve, it can be considered that the spool hardness is low, and the main cause of the valve is too early. It is recommended that the design department will increase the surface hardness of the valve heart and improve the valve thermal material.
The three excavators that were repaired by the above method were used for hundreds hours, and no turn-free failures occurred, ensuring the normal operation of the excavator.
