GB966848A - Improvements in engine powered rock drilling machines provided with a compressor for scavenging air - Google Patents

Abstract

966,848. Percussive drills. BERGBORRMASKINER A.B. Aug. 6, 1963, No. 30904/63. Heading B4C. A rock drilling machine comprises a hammer piston 11 driven against a tool 26 by the combustion gases of an internal combustion engine and returned via air delivered to a counterpressure chamber 21 by a compressor 6, 7, a manually-operable valve 45 being provided in a passageway communicating the compressor with the counter-pressure chamber 21 and a scavenging air chamber 16 and adapted upon operation, to direct the air to either of the two chambers. The hammer piston 11 is formed with a large diameter portion 11a slidable within a cylinder 10 and defining, together with a wall 15, the counter-pressure chamber 21. The valve 45 is mounted in a casing 44 and provided with a diametral port 48 and an angular port 49. In operation, with the valve in the position shown in Fig. 2, compressed air is fed from the engine-driven compressor 6, 7 via pipes 43, 47, annular chamber 19, ports 18, into the counterpressure chamber 21 thereby returning the piston after every working stroke. When the valve is rotated to its alternative position air is fed from the compressor via a chamber 42, tubular passage 41, chamber 16a, into the scavenging chamber 16 where it then passes through a passage 25 in the drill steel. The drill is partially rotated after every stroke by means of an eccentric 29 on the engine crankshaft 4 acting on a pivoted block 31 which a connected through a link 34 to a one-way clutch 37 and gear drive 40, 22. The three-way valve 45 may be replaced by two separate manuallyactuated valves.