Self-extending dockboard

Claim 1

A dockboard comprising a ramp adapted to be hingedly mounted on a support, a lip, hinge means mounting the lip on an edge of the ramp, said lip being swingable between a pendent position and an extended position, a toggle arrangement for locking said lip in the pendent position when the ramp is substantially horizontal, said toggle arrangement including linkage connected to the lip at one end and extending inwardly beneath the ramp, a spring retaining the linkage with a toggle line thereof located above said hinge means and thereby locking the lip in the pendent position, and operating means to engage the linkage to shift the latter to start to swing the lip from the pendent position and at the same time to move the toggle line of the linkage below the hinge means when the ramp has been sequentially raised and lowered, at which time said spring acts on the linkage to assist the lip to swing to the extended position, said linkage comprising a bent link connected at one end to the lip near the hinge means thereof and extending therefrom beneath the ramp to an inner end above said toggle line when the lip is in the pendent position, a lock-assist first member pivotally connected at an outer end to the inner end of the link and inclined inwardly and downwardly therefrom to an inner end, an actuating second member pivotally connected at an outer end to the link between the ends of the link and inclined inwardly and downwardly therefrom to an inner end, and a sleeve pivotally connected to one of said members remote from said link and through which the other of said member slidable extends, said spring being connected to said first member near the inner end thereof and to the ramp near said link, whereby said spring normally maintains the connection between said first member and the link above said toggle line to lock the lip in the pendent position.