The sucker of the surface grinder can't be lifted by hydraulic pressure, but it can be lifted without hydraulic pressure. What happened?

The hydraulic pump circuit of the surface grinder works independently. As long as the oil pump is started and the oil pressure is normal, whether the magnetic workbench is used or not will not affect the oil pressure and other operations of the grinder. The start of the magnetic workbench will affect the oil pressure. Only when the power supply of the hydraulic pump is directly cut off, or when the power supply of the oil pump is stepped down out of phase, it is possible that the oil pressure is gone. It is recommended to check whether the magnetic workbench is normal and whether there is any problem with the control circuit.