PNEUMATIC PERCUSSION DEVICE FOR MAKING HOLES IN THE GROUND BY PACKING THE LATTER

1,261,304. Boring earth. INSTITUT GORNOGO DELA SIBIRSKOGO OTDELENIA AN SSSR. 27 Feb., 1970, No. 9699/70. Heading E1F. A pneumatic percussion device for making holes in the ground by packing the latter comprises a housing I with a pointed front portion, a striker 2 which divides the interior of the housing into front and rear chambers 3 and 4, a compressed air feed pipe 7 extending into the shank of the striker, and a sleeve 11 on the pipe and which is movable on movement of the striker alternatively to open and close an aperture 9 in the pipe leading to the rear working chamber 4. The sleeve is moved by a pin 14 on the striker engaging one of the ribs 12, 13 on the sleeve. At the end of the forward stroke of the striker which impacts against the housing to move it forwardly, air is fed to the chamber 3 through openings 6 from the end of pipe 7 to return the striker. In the embodiment shown air is alternatively exhausted from the chambers 3 and 4 through opening 16 into pipe 15, while the striker can be arranged to impart rearward impacts to the housing to withdraw it from the hole by moving pipe 7 backwards relative to the housing by means of thread 18. In another embodiment air is exhausted from chambers 3 and 4 through an aperture in the housing uncovered by movement of the striker.