Poly-V pulleys

A poly-V pulley formed from a sheet metal cup-shaped blank, comprising:

• a cylindrical wall of continuous material, with inner and outer peripheral surfaces, a portion of the cylindrical wall being thicker than remaining sheet metal material from the blank, the thicker portion having a plurality of deep, parallel V-shaped annular grooves in the outer peripheral surface, alternating with parallel, annular partition walls, the alternating annular grooves and partition walls being adapted for receiving poly-V belts, the inner peripheral surface of the thickened portion having a plurality of shallow V-shaped annular grooves of triangular cross-section arranged parallel to one another and aligned between the grooves of the outer peripheral surface, the inner peripheral surface being flat between said shallow V-shaped annular grooves;
• and,
• annular flanges at opposite ends of the thicker portion projecting radially beyond the partition walls, the flanges having peripheral steps for secure engagement between the pulley and the poly-V belts.