The necessity of safety door switch protection for double girder bridge crane

A 10t double beam bridge crane in a certain unit has its power indicator light on and the control linkage table indicator light on, but it cannot be started. After inspection by maintenance personnel on site, it was found that the safety door from the driver's cab to the walkway was not closed. When the maintenance personnel close the safety door and all operations of the crane are normal, this is a false fault.

In the safety protection of cranes, there is a door switch on the hatch door, driver's cab door, and maintenance door. When the crane driver or maintenance personnel go to the crane for maintenance, they must open the hatch door to the crane platform or open the maintenance door to the crane track beam. At this time, the normally closed contact of the electrical switch on the opened door is disconnected, and the main contactor of the electrical box is released, thereby cutting off the power supply of the crane and preventing it from starting. At the same time, this protection protects maintenance personnel from the threat of live wires on the trolley on the bridge, and also prevents others from starting and driving and injuring maintenance personnel. The protective function of the safety door switch is very necessary.