GB654185A - Improvements in hammer drills for producing drill holes in rock or similar material - Google Patents

Abstract

654,185. Percussive drills. AKTIEBOLAGET ATLAS DIESEL, ANDERSSON, G., and SVENSSON, S. L. March 15, 1948, No. 7778. [Class 124] [Also in Group XXVI] A compressed air driven percussive drill has a differential piston, a drill turning device independent of the motion of the hammer, and a valve device including an annular valve seat at the periphery of the cylinder and a valve cooperating with the seat. As shown, a differential piston 2 reciprocates in a cylinder 1. the narrow diameter of the piston being guided in a lower cylinder head 12 which carries a compressed air driven drill turning mechanism 42, illustrated in Fig. 2 (not shown). The upper end of the cylinder 1 carries a valve seat on an axial flange 31 which co-operates with a valve 9 to admit air to the top of the piston. The valve 9, Fig. 3, comprises two annular flanges 28 and 29 on which are valve seats 35 and 30 respectively. A space 33 between the flanges is in communication with an air supply and also in restricted communication with a space 32 surrounding the flange 31 and a space 34 between the flange 28 and a ring 6 mounted between the cylinder 1 and a top head 4. An annular passage 37 leads from the inner edge of the seat 36 to a chamber 8 communicating with the underside of the piston. Air leaking round the small end of the piston may escape through openings 47 and passages 48 in the chuck housing 13 or through ducts in the chuck 14. Cleaning fluid may be supplied to the bit through passages 19, 20, 21 and 23.