Patent attributes
Disclosed herein is a hinge for a folding ladder having first and second ladder frames. The hinge includes a main hinge unit, a subsidiary hinge unit, and a locking unit. The main hinge unit includes first and second support arms commonly mounted to an upper end of the first ladder frame, and first and second disc parts extending from upper ends of the first and second support arms, respectively, and being spaced apart from each other by a predetermined interval. The subsidiary hinge unit includes a subsidiary support arm mounted to an upper end of the second ladder frame, and a subsidiary disc part extending from an upper end of the subsidiary support arm, the subsidiary disc part being disposed between the first and second disc parts, with a plurality of notches being provided along a peripheral edge of the subsidiary disc part. The locking unit includes a locking block to engage into one of the plurality of notches of the subsidiary hinge unit, thus preventing both the main and subsidiary hinge units from rotating relative to each other, a press knob outwardly projected from the first disc part and being coupled to the locking block by a coupling shaft, and a return spring fitted over the coupling shaft to return the press knob and the locking block to original positions thereof.
