GB456233A - Improvements in and relating to hooks - Google Patents

Abstract

456,233. Oil-well hooks. OIL WELL ENGINEERING CO., Ltd., Cheadle Heath, Stockport.-(National Supply Co. ; Toledo, Ohio, U.S.A.) Aug. 22, 1935, No. 23620. [Class 89 (ii)] In oil-well hooks, in order to facilitate such operations as the change from drilling to the operation of removing the drill pipe from the well, the hook is provided with a device to which the elevator sections may be attached, which device being situated immediately beneath the centre of gravity of the pivoted hook, falls into position when the drill is removed from the hook. As shown in Fig. 6 the bail 51 of the elevator is engaged in recesses 65 in the yoke 5, 6 which swivels on the base of the hook. The hook may be locked in either drill receiving or elevator receiving positions. The hook is spring mounted, the spring 6 surrounding the stem 7 being mounted in the casing 2. The movements of the spring are damped by oil which fills the casing. The damping effect is relatively ineffective on the downward travel of the shank as a check valve 31 controlling the oil passage 30 opens. During the upward travel of the shank the valve closes and the oil flow is confined to the constriction 28 The differential piston 12 has diameters 21and 23 designed so that the oil may be transferred from one side of the piston to the other without undue compression. A device for locking the swivelling hook comprises a lock-shaft 38 mounted in the cap 16 enclosing the oil space and rotatable to bring teeth into engagement with the teeth of a lock ring 33 splined on a nut 13 screwed to the upper end of the stem 7. An arrangement for selectively locking the hook against clockwise or counter-clockwise rotation or both. Comprises spring pressed ratchets 100<a>, 100<b>, Fig. 12, engaging the teeth of the splined lock ring 33<a>. The selector rod 38<a> slidably mounted in the casing to bring cams 103<a>, 103b into engagement with the selected operating-rods 102a, 102b controlling the ratchets. A spring-pressed detent 106a working in grooves 105<a> facilitates the rotation of the rod in the selected position. Translation of the rod to the selected position is permitted by the engagement of the pin 107<a> in the transverse slot 109 out of which lead circumferential recesses 108<a> corresponding to the operative positions of the rod.