993,365. Percussive drills. WESTINGHOUSE AIR BRAKE CO. March 17, 1962, No. 10295/62. Heading B4C. [Also in Division F4] A percussive drill 40 for tapping a blast furnace is mounted on an arm 39 clamped to the rigid tube 77 extending from a boom 38 pivotally mounted on a base 37 disposed to one side of the iron runner 34, the said boom being movable vertically by hydraulic cylinder 57 and laterally by another cylinder 61, Fig. 2 (not shown). The mounting base 37 includes a vertical face plate 47 carrying a pivot shaft 49 on which is swingably mounted a bracket 52 with lugs 53 and 54 respectively and pivotally carrying the boom 38 and the cylinder 57. The plate 47 also carries a swivel support on which the cylinder 61 is pivotally mounted. The arm 39 also carries an air motor 41 which advances or retracts the drill 40 on its carriage 96 by chain and sprocket gearing 92-95, Fig. 10. The drill 40 always takes up the same position relative to the tap hole 33 due to stop 74, Fig. 5, in the cylinders. The drill bit is supplied with compressed air during use through passageway 114, Fig. 10, extending through the rod 84 the forward end of which may be detachably secured by an adaptor 115. Operation of the cylinders, the air motor 41 and the drill 40 are manually controlled from a console 42 located at a safe distance from the tap hole.