GB440625A - Automatic feed for rock drills - Google Patents

Abstract

440,625. Percussive drills. CHICAGO PNEUMATIC TOOL CO., 6, East 44th Street, New York, U.S.A. Aug. 2, 1935, No. 21988. Convention date, Sept. 1, 1934. [Class 124] A feed for a rock drill is of the reaction type, so arranged that a rearward blow of the piston produces a forward feed. The feed mechanism is contained in a casing 32, 33 and 34 mounted on the end of the feed screw 28. When the steel is free from the rock face the forward blow produces forward movement but opposite rotation of the feed screw is prevented by the pawls 48a acting on the ring 40. When the steel engages the work it prevents forward blows on the drill body, and backward blows therefore produce backward movement of the screw 28 compressing the spring 70 and rotating the ring 80 splined to engage the helical flutes 76. The end of a spring 85 enters a notch in the ring 80 and allows this to rotate in one direction but opposite rotation is prevented by the spring expanding against the casing 82. Hence when the spring 70 expands the screw 28 is rotated to feed the drill forward. A shaft 57 has three angular positions, to engage pawls 48a for forward feed, to engage pawls 48b and release casing 82 for backward feed, and to release all these for hand positioning. The cam handle 100 adjusts the pressure between the brake surface 109 and the ring 40 to adjust the rate of feed.