Table with leaf and locking system

Claim 1

In combination: a platform having a horizontal surface and an upright support beneath said horizontal surface, said support having a dimension of height; a horizontal first hinge means on said platform; a rigid leaf pivotally mounted to said platform by said first hinge means to permit the leaf to hinge around said first hinge means; horizontal second hinge means on said leaf spaced from first hinge means; a lock shaft having an axis of motion, and being pivotally mounted to said second hinge means; third hinge means attached to the support at an elevation below said horizontal surface; and releasable lock means pivotally mounted to said third hinge means, said lock shaft being engaged to said lock means for axial movement therein, whereby a three link locking system is created for the leaf as follows: a first rigid link between the third and first hinge means, a second rigid link between the first and the second hinge means, and a third rigid link between the second and third hinge means, said lock means being so constructed and arranged as releasably to lock the shaft thereto and at any shaft position in the range of permissible positions, thereby to adjust the length of the third link and the angle of the leaf, said three link system being rigid when the lock means is locked, in which said lock shaft bears rack gear teeth, and in which said lock means comprises an idler gear with teeth meshed to the rack gear teeth, and a lock gear having teeth always meshed to the idler gear teeth and so disposed and arranged that they can also be meshed with the rack gear teeth to lock the gears together or removed therefrom to enable the rack gear teeth to move relative to the idler gear.