Slow working speed and insufficient overall power are common faults in medium and large excavators, usually related to hydraulic system problems, insufficient main pump output, or blockage of control valves. This case introduces a complete diagnosis and repair plan based on actual maintenance practices.
An excavator used in earthwork construction showed obvious weakness in boom lifting, bucket rotation, and walking. The operation response was slow, and the working efficiency dropped significantly, although the engine speed was normal. The maintenance personnel first checked the hydraulic oil level and found it was within the normal range, but the oil was slightly contaminated and had not been replaced for a long time.
Next, the pressure of the main hydraulic pump was tested. The measured pressure was significantly lower than the standard value specified by the manufacturer, indicating that the pump could not establish sufficient working pressure. Further inspection revealed that the hydraulic pump slippers and swash plate were worn, the piston cylinder was damaged, and the control valve spool was stuck due to oil contamination, resulting in internal leakage and insufficient flow output.
The repair steps included draining all contaminated hydraulic oil, thoroughly cleaning the hydraulic oil tank and pipelines, replacing the hydraulic oil and high-precision filter elements, repairing or replacing the worn parts of the main pump, and cleaning and calibrating the control valve. After reassembly, the hydraulic system pressure was adjusted back to the standard range, and the machine was tested under actual working conditions.
The excavator's movement speed and power returned to normal, and the fault was completely resolved. To avoid similar problems, equipment users should maintain the hydraulic system regularly, use high-quality hydraulic oil, replace filters on time, avoid mixing different types of hydraulic oil, and pay attention to keeping the hydraulic system clean to prevent impurities from entering.
