GB499616A - Rotary jar for use in well-drilling operation - Google Patents

Abstract

499,616. Well-drilling jars. KAMMERDINER, J. A. Feb. 11, 1938, No. 4319. [Class 85] A jar for use in well-drilling operations comprises means actuated by relative movement of the telescopic parts for stressing a spring, means for holding the spring against release of said stress, and means engaging said holding means for preventing release until said stress has reached a desired degree, the engaging means being actuated to release the holding means by continued movement of the telescopic parts to enable the hammer to strike the anvil. In Fig. 1, a shank 3, adapted to be Secured to the fish, is splined at 6 to the lower head 8 of an outer barrel 2 secured above to the drill string ; a flushing- fluid conduit 17 is threaded to the shank 3 and is slidable through a packing 22 in the upper head 10 of the barrel. A hammer member 24 is slidable on the conduit 17 and is threaded to a sleeve 25 with a shouldered lower end supporting an outwardly shouldered ring 34 pressed by a spring 46. Superposed conical spring rings 28 are supported below the hammer on a flange 27 within the barrel 2, a grooved ring 30 engaging the lowest pair of rings 28 and forming an abutment for the spring 46. Clutch dogs 33, pivoted at 36 to the shank 3, co-operate with a cam 35 in the barrel 2, whereby, on pulling the barrel 2 upwardly, the heads 38 of the dogs 33 first engage the ring 34 ; during further upward movement of the barrel, the spring rings 28 are compressed until the dog heads 38 pass the cam 35 and release the ring 34, the spring rings 28 then causing the hammer 24 to strike the upper head 10 of the barrel. The strength of the blow is varied by adjusting the hammer on the sleeve 25 while a stop ring 47 limits extension of the jar. In Fig. 9, the hammer 58 is carried by a mandrel 57 surrounded by a spring 60, while latches 62 project from a sleeve 63 secured to the shank 51 and surrounded by a spring 64 resting on a shouldered sleeve 67 and formed of dished resilient annuli 80 and intermediate flat annuli 81. On moving the barrel 50 upwardly, a restricted bore 71 first forces the heads 72 of the latches into an annular groove 73 in the mandrel, and the spring 60 is then compressed. Towards the end of the movement, sleeve 67 engages the lower head of the barrel, and the spring 64 is then compressed to increase the tension in the device. When the latch heads 72 pass below the bore 71, the mandrel is released and the hammer strikes its blow. In both forms, collapsing the jar automatically resets the parts.