GB1289872A - - Google Patents

Abstract

1289872 Releasable fastenings ALLIANCE MACHINE CO 4 March 1970 [9 July 1969] 10347/70 Heading E2B Tie-down mechanism for releasably holding an object against movement relative to a fixed structure, comprises a first link 23 pivotally connected at its one end to the fixed structure, a tie-down link 24 pivotally connected at its one end to the other end of the first link and free at its other end, said free other end being engageable over a tie-down pad 15 fast to the object, and extensible and contractable operating means 26 pivotally connected at its one end to the fixed structure and at its other end to the toggle constituted by the two links at a point adjacent the pivotal connection between the links, the arrangement being such that when the two links are substantially in line with one another and the free end of the tie-down link is engaged over the tie-down pad, contraction of the operating means will cause relative angular movement of the two links, reducing the overall length of the toggle and applying a tractive force between the structure and the object. As described four of the tie down mechanisms are used for securing a gantry crane to the deck of a ship in storms; the deck carries rails 11 for the crane 12 having a four legs 14 with wheels 13 engaging the rails. Each leg is provided with one of the pads 15 extending from the side thereof which are engageable by the link 24 of respective tie-down mechanisms. The deck carries a platform alongside each rail made up of a pair of spaced vertical members 17, 18 and a top member 19, the top member being provided with upstanding post 20 carrying a shaft 22 to which the first link 23 of a pair of the tie down mechanism is pivoted. The tiedown link 24 of each mechanism consists of a U shaped rod which carries a screw jack mechanism 25 the rod 24 being engageable with the upper side of one of the lugs 15 and the jack with its underside. The extensible and contractable means 26 is a turn-buckle mechanism which is pivotally connected to the top member 19 of the platform and to the free end portion of the link 23 adjacent its pivot with the tie down rod 24. The rod 24 carries a crank arm 27 which is connected by a hydraulic jack to the top member 19 of the platform. Operation of the jack rotates the rod 24 from its clamping position on pad 15 to a releasing position substantially at right angles to the clamping position. Fixed to the platform are a plurality of screw jacks for engaging the legs to prevent side movement and the platform also pivotally carries screw jacks which are engageable with hooks on the respective legs to prevent the crane moving along the rails.