GB816271A - Improved rotary core drill - Google Patents

Abstract

816,271. Earth-boring apparatus. LONGYEAR CO., E. J. June 6, 1957, [June 15, 1956], No. 18013/57. Class 85 A rotary core drill comprises a drill string 10, a sleeve 11, a wear coupling 12 having hardened lands 14L, a core barrel inner tube assembly 50, a hanger and valve coupling 17, core barrel outer tube 18, a reamer 19 and a bit 20. The assembly 50 is suspended from the coupling 17 and encircles the stem 66A of a bearing element 66 having a core lifter 75 screw threaded thereto. When the core lodges in or fills the core tube 72 the assembly 50 tends to lift relative to the drill string and this movement is opposed by spring-loaded latch dogs 53A, 53B. A rubber collar 61 is disposed between the members 50 and 66 whereby relative movement between said parts will expand said collar to block the fluid supply passage A.S. To withdraw the core barrel inner tube the drill string is retracted, whereupon the collar 61 is unloaded and the core lifter 75 moves upwardly relative to a split ring 76 to break off the core. An overshot 83, 84 is then lowered into the drill string, the pawls of which engage the spearpoint 80E-80D of a bearing tube 60 with a coller 84 in alignment therewith. The sleeve 60 is slotted so, as it moves upwardly, it extends the dogs 53A, 53B, the sleeve being retained on the member 51 by a rivet 55. In a modification (see Figs. 8-13, not shown), the coupling 17 above referred to is lengthened and the assembly 50 is provided with a O-ring to prevent a blowback of the drilling fluid.