US 4,360,180 AGranted

Device for locking the drawing board of a drawing table assembly

AssigneeJeandal

InventorAlain Bruneau

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Abstract

A drawing board is mounted on a support column slidably guided by a vertical pedestal structure and is supported by a cable passing over a pulley which is urged upwardly by a gas cylinder to counterbalance the weight of the drawing board. Opposed brake shoes mounted by toggle linkage on an inner support member are biased into engagement with inner surfaces of the support column by springs acting on sliding pivots of the toggle linkage. The normally engaged brakes are releasable by a foot pedal connected by a rod with a sliding yoke on which the sliding pivots are mounted. The rod is connected with the yoke by engaging in a notch in an edge of the yoke. In the event of breakage of the cable or failure of the counterbalancing cylinder, a safety device is actuated to disconnect the rod from the sliding yoke and thereby permit spring actuation of the brakes to prevent the drawing board from falling.

Claims10

Dependent claims

In a drawing table assembly comprising a drawing board mounted on a support column guided for vertical movement in a pedestal structure and supported by a cable passing over a pulley biased in a direction to counterbalance the weight of the drawing board, a safety device comprising a vertical inner support member inside said column, brake means comprising brake shoes mounted by linkage on opposite sides of said inner support member and engageable with inner surfaces of opposite sides of said support column, spring means acting on said brake shoes to press them into frictional engagement with said support column, means for releasing said brake means, said brake releasing means comprising a release member connected with said brake shoes and movable to withdraw said brake shoes from said inner surfaces of said support column against the action of said spring means, a foot treadle, and control member connecting said foot treadle with said release member for operation of said release member by said foot treadle to release said brake means, and safety means for sensing tension in said cable and for disconnecting said control member from said release member upon loss of tension in said cable, whereupon said brake shoes are pressed into engagement with said support column by said spring means.

Dependencies are inferred from the claim text.