GB369637A - Improvements in or relating to grab buckets - Google Patents

Abstract

369,637. Grab-buckets. PRIESTMAN, S. H., Holderness Foundry, Hull. Dec. 23, 1930, No. 38728. [Class 78 (iv).] Relates to grab-buckets of the kind wherein the jaws are hinged so as to swing down to discharge their load, being urged into their load retaining position by tension in the closing ropes, and held in this position by constraining links pivoted at their lower ends to the jaws and movable lengthwise in guides, pivoted to upper parts of the grab, and capable of being locked to the guides. According to the invention a movable detent is provided for each link which normally tends to move into a position in which it can lock the link to the guide when these are in a predetermined relative position, but which tends to move into non-locking position when the jaws approach one another within a certain limiting distance. As shown, the jaws 10 are pivoted at 12 to arms 14 which are pivoted at 16 to a'member 18 adapted to receive a sliding rod 20 connected to the holding rope 28. Constraining links 30, pivoted to the jaws at 31, can slide through guides 32 pivoted at 52 to toggle links 22 which are pivoted to the arms 14 and to a casting 26 on the rod 20. The closing ropes 34 are guided over sheaves 36, 38, mounted on the member 18 and the links 30 respectively, and are anchored by wedges 40 engaging sockets 42 formed in lateral extensions of the links. On hauling in the closing ropes 34 with the jaws apart, and tilted as shown in dotted lines in Fig. 2, the jaws swing upwards causing the links 30 to slide upwards through the guides 32 until the ends of weighted or spring controlled pawls 44 engage notches 46 in the links and lock the links to the guides and hold the jaws in the raised position as shown in Fig. 1. The grab is now lowered on the holding rope 28 and digging proceeds. As the jaws move inward, the links 30 approach the vertical and cam surfaces 48 thereon ride up guides 50 on the casting 26 and permit.the pawls to move out of the notches as shown in Fig. 2. The jaws will now swing down to discharge their load on paying out the closing ropes. The pawls may be disengaged from the notches by stops on the links. 22 engaging their lower ends. In order to vary the angular position of the jaws when apart, the guides and links 22 are provided with additional pivot holes 56, 56A, respectively, which are in register when the grab is in the closed position. Specification 338,225, [Class 78 (iv), Loading &c.], is referred to.