GB1253275A - Improvements in pressure fluid actuated rock drills with feed cylinder and control means therefor - Google Patents

Abstract

1,253,275. Feeding rock drills. ATLAS COPCO AB, 13 Feb., 1969 [16 Feb., 1968], No. 7843/69. Heading B4C. A pressure fluid-actuated rock drill 10 has a feed leg 12 which is extended and retracted by increasing or decreasing pressure above and below a piston 14, the fluid pressure flow to and from the chamber 15 above the piston 14 being controlled by a ball valve 26, and that 'to and from the chamber 16 below the piston 14, by a sleeve valve 29, both valves being actuated by a single manually movable member. Pressure fluid is fed through an inlet 22 to a throttle valve 21, which, when open, supplies pressure fluid through conduits 25, 28 to the ball valve 26 and sleeve valve 29. The valve positions are varied by movement of a plunger 37, 37<SP>1</SP> which pushes a spring 36 against the ball valve 26 to close it. The plunger 37, 37<SP>1</SP> is moved by rotating a twist grip 43 having an eccentric 48, bearing against a collar 49, or pushing a button 50, the twist grip having a rachet 47 engaged by a plunger 46 to maintain any intermediate position. When the valve 26 is open, Fig. 2, i.e. with minimum compression of the spring 36, pressure fluid is allowed to flow from conduit 25 to the chamber 15 via conduit 33, whilst the pressure in chamber 16 is relieved through conduit 34 and ports (54), (42), Fig. 4 (not shown), causing the feed leg to expand. On turning the twist grip 43, the plunger 37, 37<SP>1</SP> compresses the spring 36, reducing the inflow pressure through conduit 25 and relieving the chamber 15 via conduit 33, annular grooves (52), (53), Fig. 4 (not shown), and ports (42), (54), Fig. 5 (not shown). For retracting the feed-leg the button 50 is pushed so that a collar 51 on the plunger 37, 37<SP>1</SP> moves the sleeve valve 29 to allow pressure fluid to flow into the chamber 16 from conduit 28 via an annular groove (40), Fig. 5 (not shown), and conduit 34 the chamber 15 still being relieved. The sleeve valve acts against a spring 38 which returns the valve when the button 50 is released, this spring being of greater strength than the spring 36 to warn the operator that further pushing will retract the feed-leg. The button 50 can be pushed to relieve the chamber 15 at any position of the twist-grip 43.