| 摘要 |
A pair of door-sections make up a mine ventilation door. The door-sections are hinged to the side-walls of the passage. One of the door-sections opens upstream and the other downstream, so one is blown open, and the other blown closed, by winds passing through the passage. A linkage couples the door-sections, and harnesses the blow-open force and balances it against the blow-closed force, whereby only a small actuation force is needed to open and close the doors. The linkage ensures that the arcuate travels of the two door-sections are equal, or otherwise correspond.
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