The jam of the valve core should be related to the automatic extension of the piston rod, and the seal in the jammed cylinder is likely to be seriously damaged. Therefore, the internal leakage test of the stick cylinder is performed as follows: return the main control valve of the stick cylinder to normal; when the stick cylinder extends to the end of the stroke, remove the oil inlet hose with the rod cavity; after the engine starts, operate the pilot Control the valve handle to make the stick cylinder continuously supply oil without entering the rod cavity. Observe whether the rod cavity leaks oil. The test results show that a large amount of hydraulic oil flows out at high speed from the oil port of the stick cavity, indicating that the seal in the stick cylinder has been seriously damaged.
When inspecting the hydraulic oil tank, a large amount of iron filings was also found at the bottom of the oil tank. After the stick cylinder is damaged, a large amount of iron filings generated by the inner wall scraping is adsorbed on the oil inlet filter element, resulting in insufficient oil supply when the main pump sucks oil, and whistling noise is generated. Replaced a new stick cylinder, carefully cleaned the hydraulic oil tank, and replaced all hydraulic oil and oil inlet and oil return filter elements. After installation and commissioning, after 100 hours of trial operation, the performance of the excavator returned to normal.
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