GB191504004A - Improvements in Valves and Valve Gear for Percussive Rock Drills, Tools and the like. - Google Patents

Abstract

4004. Rayner, G. H. T. March 13. Fluid-actuated gears; slide valves, piston.- In percussive rock drills &c., the air supply is controlled by a piston valve b one end b<2> of which is provided with a recess c connected to the atmosphere and fitted with a fixed piston d so that the effective area of this end is less than that of the end b<1>. The air entering at a passes by the channels a<1>, a<2> to the two ends of the valve, which is moved to the right, and into the cylinder by the passage a<1>. The main piston y is moved to the right until a. port e is uncovered, whereupon the pressure on the collar b<1> of the valve falls, so that the valve is forced to the left. The air then passes by the passages a<2> to the right of the piston y and forces it to the left. During this movement, the cylinder to the left of the piston is open to exhaust, first through the port e, and then by the passages e<2>, e<1> and ports z. When the piston covers the passage e<2>, the air trapped between the piston and the end of the cylinder is compressed and forces the valve to the right. During the movement of the piston y to the right, the cylinder is connected to exhaust by the passages f, f<1>, f<2> and ports z. In a modification, the fixed piston is replaced by a looseball or other piston, the annular end of the collar b<2> is open to atmosphere, and the interior of the recess c is always open to the channel a<2> and intermittently connected to the passage f. Specifications 5549/12 and 13,726/14 are referred to.