When the problem of overflow valve and pump is eliminated, start to eliminate the doubt of internal leakage of hydraulic cylinder
Let the machine press down until the workpiece cannot press down, remove the oil pipe in the lower chamber of the oil cylinder, and then continue to press down to see if there is still oil flowing from the oil cylinder
If the oil cylinder is in good condition and the oil cylinder can not be pressed at this time, the oil cylinder will never stop external fuel injection
If the oil leakage starts at a lower pressure, the internal leakage of the oil cylinder is likely to fail to seal
Note two points:
- Don’t press return button.
- Note that the oil pipe must be completely disconnected, so as to determine whether it is internal leakage of oil cylinder or that of solenoid valve in case of leakage.