PULLEY FOR POLY-V BELT

A weight reduced pulley for "K" type poly-v belt systems includes a body having an outer cylindrical surface. A plurality of raised ribs extend from said surface and run circumferentially around said surface. A plurality of trough areas are positioned between the ribs. The ribs and troughs corresponding to the location of indented and raised areas, respectively, on a poly-v belt. The ribs have a cross sectional profile extending radially traverse of the axis of rotation of the pulley, each rib being bounded by a pair of planar side walls at relative angles of 40.degree. + 0.5.degree.. The side walls terminate in a 140.degree. arc having a radius of 0.5 mm, the outermost point of said arc terminating 0.96 mm inward of the intersection of the upward projections of the planar side walls or apex. The planar side walls extend radially inward at least 3.44 mm from said apex. The trough areas are bounded by the outer cylindrical surface of said pulley, said surface being 3.57 mm from said apex. The outer cylindrical surface is flattened in cross section in said trough areas and a fillet having a radius from 0.25 to 0.35 mm forms a transition between said planar side walls and said flattened surfaces. The pulley incorporates a mounting plate and has an inner cylindrical surface concentric with said outer surface. The inner cylindrical surface extends from the mounting plate to an open periphery. For a pulley having an effective diameter of 150 mm, the thickness of the pulley between the outer cylindrical surface and the inner cylindrical surface is 1.14 mm. In an alternative embodiment, the inner cylindrical surface alternative embodiment, the inner cylindrical surface is tapered towards the open periphery so that for a similar 150 mm pulley, the thickness varies from 1.14 mm adjacent the mounting plate to 0.89 mm adjacent the open periphery. The pulley is manufactured by concurrently compressing and impressing a can-like blank of hot rolled low carbon steel material with spin forming tools which impress in said material the rib and trough profiles of the pulley.