The iron bar was placed across the poles of the electromagnet. Then the coil of the electromagnet was connected to a battery.
这根铁条被放在电磁铁的两个极上，然后，将电磁铁的线圈接通电源。
2
An extension line with a certain distance to the steel bar discharge hole is provided with a contact travel switch. A wire is connected between the travel switch and a clutch electromagnet.