Abstract: Bolted or otherwise secured in offset relationship to one of the legs of a radio or television tower or mast is a bracket to the top of which is fixedly secured an inner sprocket. Rotatably mounted in this bracket coaxial with the inner sprocket is an inner shaft to the top of which is fixedly secured the rearward hub of an inner arm. Rotatably mounted in the forward hub of the inner arm is an intermediate shaft to the lower end of which is fixedly secured a lower intermediate sprocket carrying an endless sprocket chain drivingly connecting it to the inner sprocket. Fixedly secured to the forward hub of the inner arm coaxial with the intermediate shaft above the lower intermediate sprocket is an upper intermediate sprocket. Fixedly secured to the upper end of the intermediate shaft is the rearward hub of an outer arm, in the forward hub at the outer end of which is journaled an outer shaft.