1. Single action failure
(1) Slow movement or no movement at all.
First check the pilot oil circuit and shunt overload valve; if it is normal, check the control valve to see if the corresponding valve core is stuck; if it is normal, you should check the actuator and other parts related to it.
(2) Disturbed movements Sometimes the excavator does not need to operate and some movements appear on its own. The essence of this phenomenon is: when the working circuit should be closed, there is pressure oil entering the actuator and causing it to move. Possible failure points are: joystick and pilot valve related to the fault action (mechanically operated machine should be a tie rod), valve core and body of the control valve. The specific inspection method is: plug the corresponding pilot tubing to the control valve and test the machine. If the fault disappears, it means that the fault is in the control rod and the pilot valve; otherwise, it should be checked whether the valve core is stuck, excessive friction and wear or assembly errors, etc .; If the valve core is normal, continue to check whether the valve body and other components (such as oil seal) matched with the valve core are damaged.
2. Several actions controlled by a certain group of control valves are abnormal at the same time
(1) The faulty subsystem main relief valve is faulty. Test the machine after swapping the main relief valve in the faulty subsystem with the main relief valve in the normal subsystem. If the fault is moved to another subsystem, you can conclude that the main relief valve in the original faulty system is faulty. In the atomic system, the main relief valve works normally, and the cause of the fault should be found separately.
(2) The hydraulic pump of the subsystem where the fault is located is faulty. Among them, the damage and improper assembly of the hydraulic pump will cause the loss of several corresponding actions of the machine, and the wear of the hydraulic pump will make this group of actions slow and weak. Regardless of the form of the fault, as long as the general fault point is determined according to the above analysis method, further inspection and disassembly can finally find the problem.
Similarly, the displacement comparison method can also be used for the suspected hydraulic pump to change the pump outlet pipeline, thereby changing the working pump of the subsystem, depending on whether the failure of the subsystem changes. If it is changed, the hydraulic pump is faulty, otherwise the fault is not in the hydraulic pump.
(3) Faulty subsystem hydraulic pump adjustment mechanism is faulty. The failure of the hydraulic pump adjustment mechanism is as follows: the working conditions of the hydraulic pump cannot change with the working conditions of the working device when the machine is working. Check the pump flow adjustment plunger to see if the plunger hole can move freely. If it cannot move freely, when the working device requires the hydraulic pump to increase the flow rate, the flow rate cannot be increased due to the jamming of the adjusting plunger, and it shows slow movement. After disassembling the pump adjusting mechanism, it was found that the adjusting plunger had some grinds, which were replaced after polishing and cleaning, and the fault disappeared.
