Importance

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Abstract

The load platform of a lift is carried by a runner mounted for vertical reciprocation along a hollow guide column. Within the column the runner and its load are suspended from a short length of a leaf chain that, in turn, is suspended from a powered vertically reciprocable wire rope. The leaf chain extends between a pair of cam pawls pivotally mounted on a brake body carried by the runner, with the pivot axis of the pawls oriented parallel to the pivot axes of the links of the chain. The pawls are biased in a direction to move out of a retracted position into an extended position wherein they engage one side of the column to jam the brake body against an opposite side of the column. The pawls have a contact pin confronting one side of the chain such that when the chain is under tension it bears on the contact pin and so maintains the pawls in retracted position. Upon a partial or total failure of the wire rope inducing a loss of tension in the leaf chain, the short, pivotally connected links of the chain are readily laterally deflectable and offer no significant resistance to movement of the spring biased pawls into the extended braking position.

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First Claim