| 摘要 |
A hydraulic/pneumatic percussive device comprising a double-acting piston (60) which executes reciprocal motion and a tool or tool holder (90) which executes limited reciprocal motion due to the piston (60) striking it. The position of the tool or tool holder (90) relative to the piston stroke is maintained substantially constant by use of a spool valve (210, 211) which acts, through a drive gear (90B) and insert (90D) to apply greater or lesser fluid pressure to the tool or tool holder (90) in response to the axial thrust acting thereupon. The spool valve may be made adjustable to allow the maintained position of the tool or tool holder to be adjusted to cope with variations in axial thrust levels. The sleeve 211 of the spool valve can be made movable (left or right) thereby altering the metering position of the spool 210 and hence the strike position. The tool or tool holder may be rotated by a drive gear. <IMAGE> |
