| 摘要 |
A collector hood (25) is mounted on the feed beam (11) for a rock drill (15). The drill stem (20) extends through two annular diaphragms (31, 32) which form a rear wall of the hood (25). A pressure fluid is supplied between the two diaphragms (31, 32) and since the inner one of the diaphragms (31) is less stiff than the outer one (32), it bends inwardly so that the pressure fluid flows into the hood (25) through a clearance (42) around the drill stem whereas the outer diaphragm (32) maintains its sealing contact with the drills stem. |
