A locking hinge assembly having a first hinge plate and a sleeve bushing defining a through passageway and a tooth channel with opposing side walls; a second hinge plate and a sleeve bushing, for co-axial alignment of the sleeve bushings; and a splined pin received in the aligned sleeve bushings, the splined pin having a root diameter and at least one tooth projecting therefrom for being received selectively in the tooth channel, whereby the tooth being received in the tooth channel permits rotational movement of the sleeve barrel relative to the barrel until the pin is stopped by one of the side walls of the tooth channel.