GB370749A - Improvements in distributing valves and valve-gear for rock drills - Google Patents

Abstract

370,749. Valve gear for rock drills. INCERSOLL-RAND. CO., 15, Exchange Place, Jersey City, New Jersey, U.S.A. June 25, 1931, No. 18369. Convention date, Nov. 11, 1930. [Class 122 (ii).] A percussive rock drill is provided with a differential slide valve having a flange controlling the inlet to both ends of the cylinder and constructed so as to assure a greater flow of pressure fluid to the rear end of the cylinder than to the forward end. The sides of the flange form holding-area ; the ends of the valve constitute throwing - areas. The piston chamber C is closed by a bush E which guides the stem F of the piston D. A chuck J transmits the rotary piston motion to the tool. The cylinder is provided with an enlarged rear bore K containing a supply reservoir T, a ratchet ring W, and the head Z of a rifle bar b with which the piston D is slidably interlocked. The valve-chest comprises a block u and a plate V which forms a seat for the ratchet ring W. A bushing c is disposed in the block v and the plate V to act as a renewable bearing-surface for the bar b and to prevent leakage. The distributing- valve slides on the bushing c and has an intermediate flange g which controls the port h of the supply passage j. The valve has a forward head k of reduced diameter which works in a chamber p connected by a passage t to the cylinder, and a smaller rear hnad q which works in a chamber s connected to the cylinder by a passage u. The passages s, t have atmospheric vents w, v and are controlled by the piston. Passages x, y for inlet and exhaust lead to the cylinder ends. Passages at the end of the valve-chest communicate with the main exhaust B<1>. The flange g on the valve controlling the supply has annular recesses z, 2 which leave a stepped portion 3 in slidable engagement with the wall of the chamber d. The recess z which controls the supply to the rear of the piston is of greater depth than the recess 2 to ensure a greater flow of fluid. The opposite sides of the flange g act as holding-areas. The valve is thrown by pressure fluid supplied to the ends of the valves acting against the resistance of the fluid on the head g, the valve-throwing fluid in the chambers s, p escaping through the vents v, w respectively.