There are three main reasons for the metal band sawing machine GT-4230 which only dropped but not rose:
Solenoid valve stuck valve: There are two valves on the sawing machine. The 3C2 solenoid valve is the first to control the rising and falling of the sawing machine. If the valve core is stuck, the oil circuit will be blocked, which will cause the sawing machine to not rise.
The hydraulic oil pump is broken: If the sawing machine has been used for a long time, the hydraulic oil pump is worn out and the sealing ring is damaged, which causes the pressure of the sawing machine to fail and cannot rise.
The electromagnetic circuit breaker or the communication contactor is broken: different manufacturers have different circuits, but the principle is the same. Some manufacturers use communication contactors to control rising electrical appliances, and some manufacturers use electromagnetic relays, no matter what electrical appliances are used. But the principle is the same. If the electrical appliance sparks or continues to supply power without disconnecting the solenoid valve, the sawing machine will not rise.