GB373748A - Improvements in valve mechanism for rock drills - Google Patents

Abstract

373,748. Valve-gear for percussive tools. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Ingersoll-Rand Co. ; 15, Exchange Place, Jersey City, New Jersey, U.S.A.) April 30, 1931, No. 12744. [Class 122 (ii.).] The cylinder has ar enlarged rear bore J for the valve chest K and ratchet mechanism I arranged to the rear o: the valve-chest. The ratchet mechanism I seats on the valve-ches K and is backed by the head S provided with a throttle valve T and a pressure reservoir X The chest K comprises plates Y, Z between which is formed the valve chamber b comprising a reduced portion c and an enlarged portion d with an annular supply groove e therein. Inlet passages g, h are pro 'vided leading to the two ends of the cylinder. An oscillating-plate valve i centrally pivoted on a median line, and the wings a, h thereof control passages g, h. The'valve permits equal expansion working for both cylinder ends ; its ends bear slidably against the reduced portion c. The plate Y has shoulders q, r which engage the valve-ends to effect cut-off. When the valve occupies.a mean position, the edges of the wings slightly overlie, the shoulders, and the supply is cut off from both cylinder ends. To ensure maximum fluid flow with minimum valve lift, the valve has side recesses s. The valve action is accelerated by like pressure fluid supplied to recesses u, v through ports w, k in the valve wings. The valve movement is initiated by compression and the slight suction created on the edge of the wings, and the movement is completed by the compression.