| 摘要 |
1531337 Feed leg for percussive drill TORQUE TENSION Ltd 21 June 1977 [30 July 1976] 31992/76 Heading B4C A feed leg for a percussive drilling machine comprises a cylinder 12 in which is slidably disposed a piston 10 to which is connected a piston rod 8, the cylinder being provided with an inlet port 36 for admitting hydraulic fluid into a working chamber 7 to extend piston rod 8, a variable-volume closed chamber 46 containing compressible fluid and separated from the working chamber by a movable wall 40, and means 14 at one end of the feed leg for connecting the leg to the drilling machine. The fluid, e.g. air or nitrogen in chamber 46 absorb the shock of the recoil of the drill. A second hydraulic fluid inlet 38 may be provided to retract piston rod 8. In the embodiment of Fig. 3 (not shown) variable-volume chamber 46 is defined by the interior of hollow piston rod 8 and auxiliary piston 40. In a further embodiment the movable wall is a flexible member, e.g. a bellows or a rubber bag. |
