XCMG crane common fault maintenance and troubleshooting

Fault description: Slow telescopic action

Fault description:The amplitude varies, the arm extends and retracts (the movement is slow and the throttle must be increased), and the main and auxiliary rolls are normal.

Troubleshooting process:1. Using a multimeter to measure the power supply of the solenoid valve of the pilot valve based on the schematic diagram is correct. (Please refer to the schematic diagram of the 25K quadruple pump pilot hydraulic system.)2. Swap the pilot pipeline for amplitude up and down, if there is still no action during amplitude up, the amplitude down is normal, and it is judged that the pilot oil pressure is normal.3. Measure the pressure at the M1 port of the multi way valve, and the pressure gauges for dynamic amplitude, expansion, and winch all show 0 pressure. Replace the pressure measuring joint and measure again. The pressure during dynamic amplitude and expansion is 1MP, and when the throttle is increased to the maximum, the pressure is 7MP. Preliminary speculation is that it is due to internal leakage of pump 1 (because the pressure increases with the increase of throttle).4. Replace the main relief valve of the multi way valve with a normal product vehicle of the same model, but the pressure of the multi way valve remains unchanged.5. To accurately confirm the internal leakage of pump 1, the oil pipes of pumps 1 and 2 were disassembled and replaced at the central rotating body. The vehicle was restarted, and the dynamic amplitude and expansion were normal.6. Confirm that the chassis gear pump supplying oil to the P1 port of the multi way valve is leaking internally.Experience sharing:When solving a fault, the first step should be to analyze the fault phenomenon, clarify the thinking, and conduct step-by-step troubleshooting according to the thinking. Guessing without thinking will only waste more time.