Low-noise pulleys and methods of constructing low-noise pulleys are disclosed. In a first aspect, first and second pluralities of arms extending radially outward from the outer hub to the outer rim are angularly offset from each other about the axis of rotation to eliminate symmetry across the lateral midline of the pulley. In a second aspect, the radially outermost ends of a plurality of arms are arcuately spaced apart according to a pitch sequence describing a pseudo-random pattern of relative spacings so as to reduce or eliminate rotational symmetry of the pulley. In a third aspect, features of the first and second aspects are combined, and in one embodiment, first and second pluralities of arms are, respectively, approximately oppositely canted so as to vary the arcuate spacings of the laterally outermost ends of the arms.

Low-noise pulleys and methods of constructing low-noise pulleys are disclosed. In a first aspect, first and second pluralities of arms extending radially outward from the outer hub to the outer rim are angularly offset from each other about the axis of rotation to eliminate symmetry across the lateral midline of the pulley. In a second aspect, the radially outermost ends of a plurality of arms are arcuately spaced apart according to a pitch sequence describing a pseudo-random pattern of relative spacings so as to reduce or eliminate rotational symmetry of the pulley. In a third aspect, features of the first and second aspects are combined, and in one embodiment, first and second pluralities of arms are, respectively, approximately oppositely canted so as to vary the arcuate spacings of the laterally outermost ends of the arms.

Torsional vibration dampers for rotating shafts are disclosed that have a hub or a hub portion of a pulley-hub monolithic body that has an innermost sleeve defining a bore, an outermost ring concentric with and spaced radially outward from the innermost sleeve, and a plurality of spokes connecting the innermost sleeve to the outermost ring that each have torsional flexibility to act as a first spring to attenuate torsional vibrations. The dampers include an elastomeric member positioned concentrically against the outermost ring or the innermost sleeve of the hub, where the elastomeric member acts as a second spring to attenuate torsional vibrations, and an inertia member positioned concentrically against the elastomeric member, which places the first spring and second spring in series. The dampers may be crankshaft, driveline, or direct drive dampers, and the equivalent spring rate for the first and second springs is governed by the elastomeric member.

Torsional vibration dampers for rotating shafts are disclosed that have a hub or a hub portion of a pulley-hub monolithic body that has an innermost sleeve defining a bore, an outermost ring concentric with and spaced radially outward from the innermost sleeve, and a plurality of spokes connecting the innermost sleeve to the outermost ring that each have torsional flexibility to act as a first spring to attenuate torsional vibrations. The dampers include an elastomeric member positioned concentrically against the outermost ring or the innermost sleeve of the hub, where the elastomeric member acts as a second spring to attenuate torsional vibrations, and an inertia member positioned concentrically against the elastomeric member, which places the first spring and second spring in series. The dampers may be crankshaft, driveline, or direct drive dampers, and the equivalent spring rate for the first and second springs is governed by the elastomeric member.