GB190826448A - Improvements in or applicable to Single-chain Grab-dredgers. - Google Patents

Abstract

26,448. Richardson, H. Dec. 7. Grabs.-In single-chain grabs of the kind in which a flange on the grab-head is supported by suspended hooks during discharge, the flange is fitted with a weighted collar adapted to push the hooks apart when the open grab is slightly lifted, and the grab-head is provided with a pair of coupled pawls adapted to engage the grab chain. The outer corners of the buckets are connected by links c<1> to a block c, within which slides a hollow sleeve a<1> with mushroom head a, the relative movement between the sleeve and the block being limited by pins c<2> working in slots. The lower end of the sleeve a<1> engages a pair of balanced catches f, which are mounted in the block c and are connected to each other by a pin and slotted arms so as to ensure equal movement. Between the block c and the mushroom head a is mounted a sliding weight d with an enlarged head fitting closely beneath the mushroom head a. The hoisting- chain passes through the hollow sleeve a<1> and is connected to the usual triple winch. The loaded bucket is raised until the head a and the enlarged part of the weight d pass between, and are supported By, a pair of pivoted hooks e suspended from the jib head. The hoisting-chain is then slackened, the block c falling slightly so as to free the catches f, and the grab consequently opening and discharging. When the chain is again hauled in, the catches f engage the chain links and prevent the grab from closing. The grab is then raised slightly, and the weight d forces the hooks e to separate so that the mushroom' head a can be lowered between them.