Switch combination used in mines - is protected for safe operation in explosive atmospheres and has stepped slot locking flattened part of drive shaft

摘要

The device is used in underground mining, and has a pressure-proof case, an isolator operated by a shaft and a locking device for case cover and isolator. The isolator driving shaft (5) has a flat section (4) interacting with a link (1) operated by rotation of the locking element. It has a stepped slot (2) whose narrower part (3) corresponds to the thickness of the flattened part (5), of the shaft and the wider part (6) corresponds to the full dia. of the shaft. Rotation is impossible when the flattened part of the shaft is fitted into the narrow slot.