Abstract: A rotational control apparatus (10, 10a) for controlling the transmission of rotational forces between first and second relatively rotatable members (26, 120, 120a) includes a piston (76, 76a) interconnected for concurrent axial movement with the second member through a bearing unit (146) which enables relative rotation and concurrent axial shifting of the piston (76, 76a) and the second member (120, 120a). The pistons (76, 76a) is only interconnected to the first member (26) through the use of one or more springs (116) such that at least partial relative rotation between the piston (76, 76a) and the first member (26) is accommodated.

Abstract: A fan clutch (A') includes an eddy current drive (224) having a first, magnetic field producing drive component rotatable with the output and a second, coupling drive component rotatable with the input in the form of a sheave (50'). The first drive component includes permanent magnets (226). The second drive component is of a one-piece construction including a steel ring (238) embedded in a body portion (241) formed of aluminum. The steel ring (238) includes locating ears (310) for properly locating and retaining the ring (238) in a mold half (324). Positioning tabs (312, 314) extend from the faces (302, 304) of the ring (238) and prevent the ring (238) from floating in the volume between the mold halves (318, 324) which forms the body portion (241) during the introduction of the molten aluminum. The body portion (241) is integrally formed with circumferentially spaced air moving vanes (264) and an annular disc portion (260) for mounting to the sheave (50').

Abstract: Rotational control apparatus (A) in the preferred forms of fan clutches is disclosed including shoulder bolts (78) extending through axially extending voids (146) formed in axially extending portion (66) and flange (76) of first and second shell housings (62, 68). The shoulder bolts (78) secure the shell housings (62, 68) together to prevent relative movement therebetween. The apparatus (A) further includes a piston (80) having tabs (144) extending from the outer periphery thereof into the voids (146) and including openings having bushings (134) therein for slideable receipt on the shoulder bolts (78). Springs (138) are mounted on standoffs (210) extending in the voids (146) and abutting with the shoulder of the shoulder bolts (78).