Non pressure air door of the ideal of underground coal mine in China, mainly used for underground mine in return airway and main return airway between each connection, it has broken the traditional door structure for a long time, cleverly to wind pressure on the air door through the balance structure is transformed into a internal force , fully demonstrated the unique air structure.

The two air doors were opened in two directions . To realize linkage through the connecting rod and the support arm . Change the length of the connecting rod can adjust the air tightness.