GB200543A - An improved lifting and dumping or ring discharge grab - Google Patents

Abstract

200,543. Cooper, H. M., and Willmott, H. B. March 7, 1922. Grab-buckets.-Relates to grabs which are discharged by dumping or by engagement with a suspended ring, of the type in Which the buckets a are hinged to spreader arms b and to a lower frame d which is raised and lowered by a guided hook-carrying cross-head g. Flexible guides are provided for the cross-head g, comprising parallel ropes or chains h, Figs. 5 and 7, passing through guideways j in the cross-head. The ropes h are fixed at one end to the grab-head c, and in order to keep them taut during the opening and closing of the buckets, each rope is reeved around sheaves k, m on the lower frame d, and a sheave n on the bucket or spreader arm, and are secured to the lower frame. The spreader arms b at opposite sides of the grab are connected by links o' to an equalizing lever o pivoted on the grab-head. Cushioning. The opening movement of the buckets may be cushioned by a dash-pot, or by passing the lifting-rope i<1> over a sheave p on the grab-head and securing the end to the rim of a sheave p', Fig. 8, turning with the bucket on the outer bucket-hinge, so that when the buckets are opened the rope i<1> is wound on the sheave p<1> and the whole of the grab is raised. Releasing by dumping. The hook f, Fig. 4, on the cross-head g is constructed as described in Specification 175,325, and tends to turn to the position shown in broken lines when the shoulder f<3> is released by movement of the lever s. A weighted lever r, Figs. 4 and 7, pivoted on the cross-head rests on the lever s and disengages it from the shoulder f<3> when the grab is lowered to the ground and the weight of the buckets is no longer supported by the hook f. When the crosshead has been lifted to discharge the grab and is again lowered, the lever r rests on a bar t on one bucket so that when the hook f is engaged by the bucket hinge and returned to the normal position, the lever s engages the shoulder f<3> in readiness for closing the buckets. Releasing by engagement with suspended ring- A lever u, Fig. 7, pivoted on the grab-head passes up freely through the discharging ring, and on again lowering the grab, the lever is engaged by the ring so as to turn a lever v and raise a rod w, which at its lower end engages and raises a lever x, Fig. 4, thereby lifting the lever s and releasing the hook f.