GB185363A - Improvements in or relating to grabs, lifting-dogs and like lifting and lowering apparatus - Google Patents

Abstract

185,363. Hollick, W. J. Feb. 24, 1921. Grab - buckets; grabforks.-Relates to grabbuckets, grab-forks and the like of the kind wherein shank and catch coupling mechanism is provided within the frame or body of the grab &c. for transferring the point of suspension of the bucket segments. As applied to a grab, the buckets are locked in the closed position by the engagement of a headed pin, secured to the buckets, with axially slidable pins in the interior of a sleeve or the like connected to the lower movable sheave block or like member, the pins being withdrawn to release the bucket segments for dumping. Fig. 4 shows one construction in which spring latches 23 axially sliding in casings 20, engage the head 18 and are released for dumping by pulling the cords 34 which are connected to the latches by bell-crank levers 31. In a modified form, the springs are dispensed with, and the outer ends of the latches are confined within a wedge-shaped sleeve so as to be projected into the acting position by the axial movement of the sleeve. When the sleeve is positioned to allow play to the ends of the catches, the weight of the load forces them outwards to dump the contents. Fig. 7 shows a modification in which the re-entry of the head 13 into the catch sleeve re-sets the catches. The latches are withdrawn by bell-crank levers 31 as before, but the withdrawal rotates other levers 42 from the position shown in full lines to the position shown in dotted lines. On re-engagement, after dumping, the head 18 strikes against the levers 42 and restores them to the position shown in full lines, thus re-engaging the catches. Fig. 9 shows a construction which allows automatic retraction of the latches when the grab rests on the ground or is suspended otherwise than by the lifting-chain. The paying- out of the lifting-chain lowers the member 22 relatively to the bucket framing 14 and causes the levers 46 to be operated by the collar 47 to withdraw the catches and also to manipulate the re-setting levers 42 as before. On re-winding, the member 22 can then be drawn clear of the member 18, leaving the bucket segments free to open. On re-lowering the member 22 to close and raise the grab, the member 18 operates the levers 42 to re-set the catches. This operation brings the levers 46 into the path of the collar 47 again, and involves the necessity for passing the collar to the lower side of the levers during the operation of lowering the head on to the re-set latches. To permit this movement the ends of the levers 46 are spring-pivoted so that they can be tripped when the collar moves downwards, without affecting the remainder of the levers. For retracting the latches in mid-air, operating cords would be fitted as previously described. The head 18 may be undercut and the ends of the latches similarly shaped. In a further modification, the collar 47 can rotate on the shaft of the member 18. The movement of the member 22 is utilized to rotate the collar between two set positions through the medium of pin-andslot mechanism. In one position, the levers 46 pass freely through circumferential slots in the collar, while in the other position they are operated by engagement with the collar. As applied to grab-forks &c. the coupling head 18 is connected to the pivot of the forks and the casing 20 is connected to a cross-head to which the upper arms of the forks are connected by reds, the opening and closing of the forks being effected by the engagement and disengagement of the coupling.