Patent GB-190514949-A (GB)
Title: Improvements in, and relating to, Rock Drills.
Inventor: LEYNER JOHN GEORGE
Filed: 1905-07-20
Granted: 1906-07-20
Abstract: 14,949. Leyner, J. G. July 20. Rock drills.-In an air-actuated percussive rock drill, the bit 39 may slide in a sleeve 30 and is struck, through an interposed striking-pin 37, by the piston hammer 18 ; the sleeve.30 and with it the bit may be rotated by means of a wheel 43 rotated bv the feed-screw 47 which thus serves both to rotate the drill and to feed forward the drill cylinder. The cylinder 1, closed at the rear by a screw cap 5, is formed with axial bores 2, 3 of different diameters, the larger bore 2 terminating in a shoulder 4. An air inlet 9, Fig. 5, leads to a circumferential port 12 communicating through passages 14, plugged at the rear, with another circumferential port 13. The smaller bore 3 leads to an exhaust port 16 open to the atmosphere through a port 17. The piston hammer 18, having a bore 21, is formed in two diameters 19, 20 and is provided with ports 23 and with ports 22, some of the ports 22 being arranged radially and others at an obtuse forward angle, the outer openings of the port being on a circumferential-line. In operation, the piston being at the end of the forward stroke, air passes from the port 12 along the passages 14 to the port 13 and enters the cylinder between the shoulder 4 and a shoulder 20<A> on the piston which is moved to the rear. When the ports 22 pass the port 12, air enters the piston, which is cushioned and then thrown forward. At the end of the forward stroke, the air exhausts through the ports 22, 16. The hammer piston strikes a pin 37 which is mounted in the cylinder and transmits the blows to the cruciform bit 39 which may slide in the sleeve 30. The pin 37 is formed with a collar 38 and fits in the rear of the sleeve 30 and also in a' sleeve 26 having flanges which bear against shoulders 24<A>. 25<A> formed in the cylinder. The sleeve 30 is rotatably mounted in the sleeve 26 and in a hub 30<A> formed on the detachable cylinder head 31. A rubber buffer 28 located in front of the sleeve 26 is secured by a washer 29 and a flange 31<A> on the cylinder head; The sleeve 30 is formed with an integral wheel 3'5 in gear with a wheel 43 formed on a sleeve 45 mounted in a depending port 40 of the cylinder. The sleeve 45 is formed with two feathers 49 entering keyways 48<A> in a feed-screw 47 which engages a nut 46 secured to the cylinder. Guides 52 are formed on a supporting shell and the cylinder is provided with slides 53. When the feed-screw is rotated, the cylinder is fed backwards or forwards and the sleeve 45 and with it the wheels 43, 45 and the drill 39 are rotated. The operator feeds the drill cylinder forward sufficiently to keep the bit in' contact with the rock. If, however, the drill bit is not in the sleeve 30 or is not in contact with the rock, the piston strikes against the sleeve 26 and the blow is taken up by the rubber buffer 28. Preferably the drill bits are of cruciform crosssection, but other cross sections may be employed. The sleeve 45 is formed with an aperture 45<A> opposite the exhaust port 17, which permits the exhaust air to enter the sleeve and keep the screw free from dust.