GB140039A - Improvements in or relating to pneumatic hammer-drills and other pneumatic tools - Google Patents

Abstract

140,039. Soc. Belge d'Outillage Pneumatique (Ateliers Rorive). March 12, 1919, [Convention date]. Addition to 125,954. Percussive hand tools.-The automatic stop device described in the parent Specification is modified so that when the working tool moves forward owing to lack of resistance thereto, the exhausts from both ends of the cylinder are closed without affecting the inlets thereto. The piston is then held stationarv between two bodies of compressed air. In the form shown in Fig. 1, air from the inlet 0 flows past the valve N and through ports Q, R, A to raise the piston C; when the piston closes the exhaust port F, cushioned fluid lifts the valve N and fluid flows through port H to move the piston downwards, the valve being again reversed by cushioned fluid when the piston passes the exhaust ports G. When the tool K advances owing to lack of resistance, a sleeve I is also advanced by fluid acting on its rear end or on a forward shoulder M and closes the exhaust ports F, G, the inlet port A remaining open to the cylinder through elongated apertures D' in the sleeve. In a modification, the sleeve moves in an annular recess formed within the walls of the cylinder and directly open to the fluid inlet O. In the form shown in Fig. 3, the exhaust ports F, G are opened to the atmosphere through an annular groove U in a sleeve T and ports F<1>, G<1>; when the tool K advances, the sleeve T also advances under the pressure of the fluid or the blows of the piston and communication is interrupted between the ports F. F' and G, G' respectively. The ports F', G' may be deflected to open at any part of the cylinder. In a modification, the sleeve T is dispensed with, the groove U being formed in the shank of the tool K.