For the hydraulic system of excavators, when the excavator of this type is working, if the digging speed of the bucket is very slow, firstly operate other actuators. If only the digging speed of the bucket is very slow, the diesel engine can be operated at the rated speed , Operate the pilot valve to overflow the large cavity of the bucket, and the maintenance personnel of the excavator use both hands to grasp the oil outlet pipe that leads from the two multi-way valves to the large cavity of the bucket cylinder. At this time, there will be two different results:
(1) Both high-pressure oil pipes have a sense of oil flow. This shows that the large cavities of the bucket have merged, and the bucket digging is still very slow, which may be caused by the following reasons:
① The overflow pressure value of the secondary overflow valve of the large cavity of the bucket is too low. At this time, a pressure gauge can be installed at the oil outlet of the hydraulic pump to make the bucket digging in an overflow state. If the pressure gauge shows a very low value, adjust the secondary overflow valve in the large cavity of the bucket. If the pressure value changes, the overflow pressure value can be adjusted to the rated pressure value. If the secondary relief valve is adjusted, the pressure value does not change, the reason is generally;
A. If the spring of the secondary relief valve breaks or yields, the damaged spring should be replaced:
B. There is a foreign matter jam between the valve core and the valve core seat, which causes the overflow valve to overflow prematurely. The foreign matter should be removed.
② The piston seal of the bucket cylinder is damaged or worn seriously, and the piston seal should be replaced.
③If the piston rod is bent, the piston rod should be corrected, repaired or replaced.
(2) If only one high-pressure hose has an oily feel, it means that the bucket cavity has not merged, and the inspection should be continued according to the following methods:
① If the oil outlet pipe of the valve block leading to the large cavity of the bucket has no sense of oil flow, it may be caused by the following reasons:
A. The valve stem has been bonded or jammed by foreign matter. It should be matched to grind the valve stem and valve hole or remove foreign matter to make the valve stem change freely;
B. The pilot control oil pressure is too low, and the valve stem cannot be completely reversed. The pilot control oil pressure should be eliminated first;
C. The corresponding pilot control pipe is blocked by foreign matter, and the foreign matter should be removed.
②If the oil outlet pipe of valve group II leading to the large cavity of the bucket has no sense of oil flow, you can loosen the second and third thread of the pipe joint corresponding to the valve stem control oil circuit, and operate the joystick that controls the large cavity of the bucket. Increase the control angle, and observe whether the pipe joint is leaking or spraying:
A. If there is oil leakage at the loose pilot pipe joint, it means that the valve stem of the multi-way valve has no pilot reversing pressure or the reversing pressure is very low. Generally, the valve core of the reversing valve is poorly polished, rusted or stuck by foreign objects. The spool of the reversing valve should be disassembled to repair or remove foreign objects to make it move freely.
B. If oil is injected at the loose pilot pipe joint, it means that the multi-way reversing valve stem has pilot reversing pressure, it may be caused by the multi-way reversing valve stem being stuck or jammed by foreign matter and should be repaired Or remove foreign matter, so that the valve stem of the multi-way reversing valve can be switched freely.
Conclusion: The bucket is in direct contact with the external environment and working objects, so its fatigue and working intensity are very high. When encountering hard objects, do not use violent manipulation to avoid damage to the cylinder. In addition, the usual inspection, maintenance, and maintenance work should not be slack, especially the oil seals and other consumable parts. After a long period of time, the oil seals have a great chance of aging and broken. Timely detection and timely replacement can ensure that there is no failure.
