GB767167A - Improvements in distributing valve means for elastic pressure fluid driven percussion tools - Google Patents

Abstract

767,167. Engine valve gear. ATLAS COPCO AKTIEBOLAG, [formerly AKTIEBOLAGET ATLAS DIESEL]. March 3, 1955 [March 23, 1954], No. 6320/55. Class 122 (2). A piston-type percussion tool operated by pressure fluid such as compressed air has an annular sliding valve member 17 with a flange 20 seating either on a surface 18 or a surface 19 and the member 17 is raised to engage the upper surface 18 and supply air to the chamber 14 on the return side of a piston 10 by a thrower member 28 having an undersurface 37 in communication through a passage 35 with the chamber 15 on the working side of the piston; the thrower member may slide on the valve member or be secured to it by a press-fit or other means. With the valve member in the position illustrated, air from the main inlet valve 33 and a chamber 32 passes through the annular space 30 into the chamber 15. When the piston has moved down sufficiently to uncover the passage 35, the pressure in the chamber 15 acts on the thrower member to raise it against an abutment 45 on the valve member and so close the supply to the working chamber and open the supply to the return chamber through a passage 42. After uncovering the passage 35, the piston continues downward under expansion of the air until it uncovers an exhaust port 16. On the return stroke, an annular passage 43 in the piston vents the passage 35 to the exhaust port 16 and the compression of the air above the piston, acting on the effective surface 46, moves the valve member to the lower seat 19. A rifle bar 12 engages a nut 11 on the piston and, at its upper end, co-operates with a pawl and ratchet mechanism 9.