Patent GB-489933-A (GB)
Abstract: 489,933. Hooks. NATIONAL SUPPLY CORPORATION and OIL WELL ENGINEERING CO., Ltd. Jan. 2, 1937, No. 140. Convention date, Aug. 3, 1936. [Classes 44 and 89 (ii)] A hook construction comprises a body having a pair of relatively rotatable parts, one of which carries the hook proper, and a pivoted locking lever carried by one of the parts and adapted to be engaged with the other part to lock it against rotation. A spring urges the lever into locking position, whilst a cam or a catch is provided for holding the lever out of locking position. The hook, Figs. 1, 2a, comprises a bail 3 journalled on trunnions 2 on the body 1, a hook member 5 pivoted at 7 to a shank 4 extending through the body 1 and a yoke 6 secured to the member 5. A shoulder 8 on the body 1 supports a thrust bearing 10 on which a sleeve 11, slidable relatively to the shank 4, is rotatably supported. A helical spring abuts against a flange 13 on the sleeve 11 and a stop plate 14 engaged by a collar 15 threaded on the shank 4. Abutment of the sleeve 11 and stop plate 14 limits the travel of the body 1 downwardly and abutment of shoulders 46, 46<1> limits the upward travel. 47 is a lubricant fitting for the thrust bearing 10. The hook member 5 has an opening 17 closed by a bill 18 pivoted at 19 and having a finger 20 to close the bill automatically on application of the load and to prevent opening when loaded. The bill 18 has shoulders 27 engaging recesses in the member 5 and is locked in the closed position by a pivoted latch 22 engaging a member 21 on the member 5 ; a spring 23 acting on a plunger 24 retains the latch 22 in the closed position. A guard 25 prevents accidental opening of the latch which is manually operated through an aperture in the guard. The yoke 6 is secured on a trunnion 29 by a threaded collar 30 and may be locked in various positions by means of a plunger 31 ; openings 33 receive elevator bails. The shank 4 may be locked against rotation relative to the body 1 by means of a floating lock ring 34 splined to the collar 15, a lock member 37 engaging recesses 36 in the periphery of the ring 34. The member 37 is pivoted on a pin 38 in the cap 39, an operating lever 40 being secured to the pin 38. A latch member 41 is journalled on a pin 41<1> in the cap and is connected to an extension 44 on the locking member 37 by a spring 43 ; complementary latching surfaces 42, 42<1> are formed on the members 41, 37. Secured to the pin 41<1> externally of the cap is an actuating lever 45. Operation of the lever 45 automatically locks the shank 4 against rotation, whereas operation of the lever 40 unlocks the shank. In a modification, Figs. 4, 5, the spring 12a engages a stop plate 11a carried by the bearing 10a at its lower end and a flange 14a on the sleeve 15a secured to the shank 4a at its upper end. A stop shoulder 60 is formed on the shank. Supported rotatably in the body 1a is a spider 64 having vertical keyways 65 engaging keys 66 on the sleeve 15a. Locking lugs 36a, formed integrally with end flange 67, are engaged by a locking member 37a pivotally mounted on a pin 38a. A cam 41a, mounted on a pin 42a, has a nose 70 fitting a recess 71 in the member 37a ; an operating lever 45a is secured to the pin 42a externally of the casing; a spring 43a engages the member 37a. To check excessive recoil of the spring 12a, a snubbing device is provided comprising a piston 78 secured to the shank 4a and mounted within a cylinder 77 on the interior of the spider 64. The piston carries a check valve 80 mounted in a passageway 83 connecting the cavity 82 with the cylinder 77 and adjustably controlled by a needle valve 84. Oil is introduced into the hook through an opening 85 and reaches the cavity 82 through ports 87, 88 ; a vent 91 is provided in the cap 39a.