Patent GB-115462-A (GB)
Title: Improvements in or relating to Rock Drills.
Inventor: VEASEY JOHN HERBERT
IPC: E21B19/086
Filed: 1917-05-04
Abstract: 115,462. Veasey, J. H. May 4, 1917. Percussive drills.-In a rock drill with fluidpressure feeding means, the feed being checked by liquid, some of which is exhausted at each full stroke of the drill, means are automatically actuated on the completion of the forward stroke for supplying liquid under pressure to return the drill. The feed-cylinder 10 is secured to the boss 12 which ordinarily carries the feed-nut, and the feed-piston 9 to a head 7 connected by rods 6 to the cradle 1. The piston 9 has a port 16 opening between the packings and permitting escape of leaking fluid. The front chamber 14 of the cylinder 10 is constantly supplied with air through a pipe 20 connected to the inlet side of the valve 19 controlling the supply of actuating fluid to the throttle valve 17 of the drill 4. The rear chamber 15 of the cylinder 10 contains water and is connected by a pipe 22, with branches 22a, 22<b> to a valve 24 which controls communication between the pipe 22 and an exhaust port 63, a pipe 61 leading to a water supply 62 and a pipe 25 leading to an exhaust valve 26. The pipes 20, 22 have readily-connectible joints 21, 23. The valve 19 comprises a poppet member 73, Fig. 9, normally held open by a spring 74 and adapted to be closed by a wire 72 connected to a trigger 70; in the closed position, a leakage port 74' permits slow reciprocation of the drill piston to prevent jamming of the tool. The valve 24 is carried by a plate 48 secured to the cylinder bolts 50 and comprises a plug with a handle 56 controlled by a spring 65, Fig. 4, and with a T-port controlling the pipe branch 22<a> and a straight port controlling the pipe branch 22<b>. Stops 57, 57' limit the movement of the valve, and a spring-pressed pawl 59, controlled by a wire 67 and a trigger 66, holds the valve in middle or working position. The valve 26 comprises a casing 27, Fig. 3, held to the drill cylinder 4 by bolts 36 and clips 31, metal 33 being welded to the cylinder 4 if required; a tappet 37, raised when the drill piston 35 takes an excessive stroke, acts through a rod 38, passing through washers 40, 41, 42 separated by outwardly-curved packings 44, to raise a ball 34 from its seat and open the pipe 25 to exhaust ports 47. In operation, the valve handle 56 is first pushed against the stop 57<1> to open the pipe 22 to the exhaust port 63, the air in the feed-cylinder chamber 14 then feeding the drill to its work. The drill is then started by means of the throttle valve 17, and the handle 56 being released is pulled to working position against the pawl 59, when the pipe 22 is connected to the pipe 25. When an excessive stroke of the drill piston occurs, the exhaust valve 26 is operated to exhaust liquid from the rear feed-cylinder chamber 15 and permit forward feed of the drill. On completion of the forward feed, a stop carried by the cradle acts through the trigger 66 and wire 67 to trip the pawl 59, when the spring 65 pulls the valve handle 56 against the stop 57 and so opens the pipe 22 to the water supply 62 to return the drill; during this return, a spring-pressed stop actuates the trigger 70 to close the air valve 19 and reduce the speed of the drill piston 35. The valve 19 is re-opened by closing the throttle 17.