GB191416035A - Improvements in Valve Gear for Rock Drilling and like Machines. - Google Patents

Abstract

16,035. Stephens, W. C. July 4. [Cognate Applications, 23,434/14 and 76/15.] Percussive hand tools. -A rock drill or other percussive tool is provided with a fluidactuated differential valve c which is hollow and works on a projection e<1> in line with the cylinder. One face of the valve is constantly subjected to fluid pressure to move the valve in one direction, and the valve is moved in the other direction by fluid compressed by the piston and supplied through a leakage port n, Fig. 2. In the construction shown in Figs. 1 and 2, the valve is provided with three heads k, k<1>, k<2> and live-fluid and exhaust grooves l, l<1>. The recess m<1> in the valve is in constant communication with the air-supply, and the annular end of the valve is open to the exhaust through a small port o. Pressure fluid is supplied to the ports g, g<1> through passages f opening into a space f<0> communicating with the air supply. The ports h, i, j communicate respectively with the front of the cylinder, back of the cylinder, and atmosphere. The main exhaust is shown at j in the position shown, an auxiliary exhaust from the front end of the cylinder takes place through the passages h<2>, h<1>, h, p. A casing provided with a cock encloses the valve-chest. Modifications of the above construction are described. In one construction, the projection e<1> is solid, the recess m<1> communicates with the exhaust through a port connected to the recess l, and the annular end of the valve is supplied with fluid pressure. In another construction, the valve has one recess only, which alternately communicates with the supply and exhaust through passages controlled by the heads of the valve. In a modification of this construction, the supply passes through radial ports in the valve controlled by the hollow projection e'.