GB825396A - Improvements in pneumatic percussion tools - Google Patents

Abstract

825,396. Compressed-air engines; cylinders. ATLAS COPCO A.B. May 15, 1958 [May 21, 1957], No. 15644/58. Classes 122 (1) and 122 (3). A pneumatic percussion tool comprises a cylinder 1, a hammer piston 11, first and second chambers 12, 13 for compressed-air producing the working and return strokes respectively, valve means 8 for admitting air to the first chamber in which piston - controlled main and auxiliary outlets 19 and 22, 27 are formed in the cylinder wall, the total area of the outlets 22, 27 being less than that of the main outlets 19 and disposed so as to be uncovered by the piston during the working stroke before the main outlet. The cylinder 1, which is of steel and mounted in an aluminium casing 2, is also provided with a further series of auxiliary outlets 23 to be uncovered similarly on the return stroke of the piston. The holes 19, 22, 23, 27 may be evenly distributed as shown or in zig-zag lines, a separate series of main outlets 19 may be provided for each chamber 12, 13 and the auxiliary outlets 22, 27 in the chamber 12 may consist of one series of holes only. For the working stroke, compressed-air is admitted into a valve chamber 7, through the valve 8 and passages 14 into the chamber 12 and, for the return stroke, through passages 15 and port 16 into the chamber 13, the air being exhausted to atmosphere through a chamber 24.