Abstract: A coupling between a spool and a brake drum includes: a metallic base having a first axial opening formed therein for extension of a spindle therethrough; a metallic rim disposed about the first axial opening and integral with and extending in a generally axial direction from the base, with the rim including an edge having a discontinuous planar surface disposed substantially orthogonal to the axial direction; and a magnet integral with the base that magnetizes the discontinuous planar surface of the rim of the magnetic chuck. The edge has a stepped profile resembling a rectangular wave; the rim is circular and coaxial with the axial opening in the base; and the magnet includes a second opening formed in register with the first opening in the base for extension of the spindle therethrough. The magnetic chuck is disposed on the spindle between the spool and the brake drum. The magnetic chuck is secured by fasteners to the brake drum for rotation therewith about an axis of the spindle.