GB312038A - - Google Patents

Abstract

312,038. Ingersoll-Rand Co., (Assignees of Smickle, R. H.). May 19, 1928, [Convention date]. Percussive drills.-The drill cylinder contains two coaxial pistons L, U, separated by a partition G and arranged to strike concentric areas on the anvil block Y or its extension b. The pistons move oppositely under the control of a single .distributing valve g, which is itself actuated by pressure fluid admitted to passages 4, 5 alternately, exhaust taking place through ports c, d, controlled by the pistons. In the position shown pressure fluid is admitted behind the piston L and in front of the piston U through passages v, w respectively; the piston L is thus driven forward to strike the extension b, and the piston U is driven backwards, producing a cushioning action with the partition G which balances the blow. As the piston L clears the passage 5 the valve is reversed, and thereby admits pressure fluid behind the piston U and in front of the piston L through passages 2, z respectively, the fluid previously admitted escaping through ports c, d, as stated. In a modification (not shown) the partition G is omitted, and the pistons kept apart by the air cushion.