GB1209489A - Improvements in or relating to fluid-operated percussive tools - Google Patents

Abstract

1,209,489. Percussive tools. FORGES ET ATELIERS DE MEUDON. 27 Dec., 1967 [24 Jan., 1967], No. 58643/67. Heading B4C. A percussion tool actuated by incompressible liquid comprises a piston 2, which with cylinder 1 defines an upper chamber 10 and a lower chamber 12, the upper chamber being in constant communication with a pressure fluid supply port 9, and the lower chamber being alternately in communication with an exhaust port 15 and the supply port. The chamber 12 is of a greater effective cross-sectional area than the chamber 10. The tool also includes a distributer valve 3 and a pilot slide valve 4. In operation, just as the piston has struck bit 8, pressure fluid in chamber 10 forces the slide valve 4 to its lowermost position (as shown) and fluid flows from the supply port to force the distributer valve 3 against its spring, thus causing the lower chamber to be in communication with the supply port (Fig. 2, not shown). Due to the greater force being exerted on the piston by fluid in the lower chamber than that in the upper chamber, the piston will be forced away from the bit. When the piston reaches its uppermost position (Fig. 3, not shown) pressure fluid in chamber 12 will force the slide valve 4 upwardly, thus enabling pressure fluid acting on distributer valve 3 to be exhausted. The valve 3, under action of its spring 14, moves upwardly and causes the lower chamber to communicate with the exhaust port. The piston then commences its downward stroke. Excess fluid output is absorbed by an accumulator 5-7. The tool may include a rotary tool bit-holder which is rotated through a predetermined angle, during upward movement of the piston, by an hydraulic motor (Figs. 5-7, not shown).