PERCUSSIVE PNEUMATIC APPARATUS FOR DRIVING HOLES IN THE GROUND BY COMPACTING SAME

摘要

1532122 Boring earth &c INST GORN DELA SIBERS OTDELENIA AKAD NAUK SSSR 15 March 1977 10820/77 Heading E1F In a self-propelled pneumatic percussive device for driving holes in the ground including a pointed hollow cylindrical body 1 and a stepped striker piston 2 having passages 8, 9 which cooperate with grooves 13 in the body to supply compressed air intermittently to the forward working chamber 5, the striker piston 2 can be rotated between and locked in either of two positions, one position causing the device to be advanced and the other position causing the device to move in the reverse direction. In a first embodiment (Fig. 1) the striker piston 2 has two spaced radial passages 9, 10. The striker 2 is rotated by air hose 22 via spline 17 and groove 19 connection so that either passage 9 or 10 registers with groove 13, thus causing air to be supplied to the forward chamber 5 at different times in the cycle and causing the striker 2 to impact against the front of body 1 or nut 3. Air is exhausted from chamber 5 through port 15, and in one position of the striker 2 a groove 12 registers with port 15. In a second embodiment (not shown) the striker 2 is provided with a single radial passage 9 and the body 1 is provided with grooves of unequal length, the passage 9 registering with a short groove in one position of the striker and with a long groove in the other position. A similar arrangement may be used for exhausting the air from the chamber 5.