GB201241A - Improvements in grabs - Google Patents

Abstract

201,241. Callow, A. M. April 27,1922. Grab-buckets.-In single-chain grabs, (1) the side rods are formed in two parts, C, C<1>, Fig. 6, hinged at c and connected by links D to the bucket hinge E or to some other point on the lower frame l, so that the overall height of the grab is almost the same open and closed; (2) suspension hooks g on the grab head co-operate with shrouds R for automatically engaging and disengaging the suspender ring U; and (3) the grab hanging open on the chain is kept open until grounded by toggle links. For discharging at different levels more than one suspension ring may be used. A grab embodying the features (1), (2) and (3) is shown open and grounded in Fig. 1, and closed and raised in Fig. 2. The suspension hooks g are rigidly attached to a frame G pivoted at f in the grab-head. The frame G supports the upper sheave o and is connected by links J<2> with a pair of bell-crank levers such as J<1>, J pivoted on the grab-head at N. The arms J of the bell-crank levers are connected with levers K pivoted to the lower frame l at k forming toggles J, K. The lower sheave M, or sheaves M, T are mounted in the frame l, the sheave M being carried on an arm L pivoted to the frame at x. The lifting chain H is reeved around the sheaves M, o, T, and secured to the end of a lever Q pivoted in the grab-head at P. The lever Q carries a stud q engaging the lower end of the shrouds R which are pivoted to the grab-head at r. With the open grab resting on the ground, Fig. 1, and the chain H slack, the weight of the parts G, J<2>, 0, o bends the toggles J, K so that the grab is free to close. When the chain has been hauled in and the grab raised, Fig. 2, the pull of the chain H on the pulley o and on the lever Q brings the hooks g and shrouds R to the position shown, and the hooks will push the suspension ring U aside and then engage with its upper edge. On paying out the chain, with the grab suspended on the ring W, the buckets will open until the toggle-levers J, K are in line, with the lower end of the lever K locked by engagement with the lever L. The open grab can now be lifted and lowered, the hooks g being held by the bell-crank levers J<1> in position to be covered by the shrouds R so as to pass down through the ring. When the grab is grounded, Fig. 1, the chain N becomes slack, the sheave M drops and the lever L disengages the toggle-lever K.