A torsional damper is provided and is equipped with a hub fixed to a rotary shaft and having an outer circumferential surface circumferentially around the rotary shaft, an annular vibration ring having an inner circumferential surface circumferentially around the rotary shaft and with a diameter larger than that of the outer circumferential surface of the hub, and a rubber ring in a compressed state between the outer circumferential surface of the hub and the inner circumferential surface of the vibration ring, that is formed from a rubber composition containing EPDM as a main component, and has a loss coefficient (tan δ) of 0.18 or more when the surface temperature is 60±5° C., wherein when subjected to a resonance point tracking method, the maximum attained surface temperature (Tmax) of the rubber ring during continuous excitation at the resonance point and the rubber fitting width (b) satisfy a specific relational expression.

Pulley-torsional damper integrated group comprising a hub adapted to be rigidly connected to a drive member and a pulley connected to the hub. The hub comprises an inner tubular wall and an outer tubular wall. The pulley is angularly coupled to said hub by means of the ring made of elastomeric material. The elastomeric ring has an outer surface towards the pulley and an inner surface towards the hub, and an adhesive is arranged on at least one of the outer or inner surfaces.

Pulley-torsional damper integrated group comprising a hub adapted to be rigidly connected to a drive member and a pulley connected to the hub. The hub comprises an inner tubular wall and an outer tubular wall. The pulley is angularly coupled to said hub by means of the ring made of elastomeric material. The elastomeric ring has an outer surface towards the pulley and an inner surface towards the hub, and an adhesive is arranged on at least one of the outer or inner surfaces.

An isolator decoupler comprising a shaft, a pulley journalled to the shaft, a one-way clutch engaged with the shaft, a spring carrier engaged with the one-way clutch, the spring carrier having a spring carrier surface, a torsion spring having a first end laser welded to the pulley and a second end laser welded to the spring carrier, the torsion spring having a volute with a width w, an annular spring support member having a spring support member outside surface, the annular spring support member independently moveable from the spring carrier and independently moveable from the shaft, a gap g between the annular spring support member and the spring carrier, the gap g being less than the width w, the first end comprising a first end coil, the first end coil bearing upon the spring support member outside surface, the first end coil laser welded to the spring support member outside surface, a torsion spring radial contraction limited by engagement with the spring carrier surface, and the gap g and the width w have a relationship (w−2r)>(g+c1+c2) were g>0.

An isolator decoupler comprising a shaft, a pulley journalled to the shaft, a one-way clutch engaged with the shaft, a spring carrier engaged with the one-way clutch, the spring carrier having a spring carrier surface, a torsion spring having a first end laser welded to the pulley and a second end laser welded to the spring carrier, the torsion spring having a volute with a width w, an annular spring support member having a spring support member outside surface, the annular spring support member independently moveable from the spring carrier and independently moveable from the shaft, a gap g between the annular spring support member and the spring carrier, the gap g being less than the width w, the first end comprising a first end coil, the first end coil bearing upon the spring support member outside surface, the first end coil laser welded to the spring support member outside surface, a torsion spring radial contraction limited by engagement with the spring carrier surface, and the gap g and the width w have a relationship (w−2r)>(g+c1+c2) were g>0.

A pulley device configured to support a belt of a chain tensioning idler or runner roller includes a bearing having a rotatable outer ring and a coaxial fixed inner ring and a pulley having at least one C-shaped pulley part that has an inner portion with an inner surface mounted on an outer cylindrical surface of the bearing outer ring, an outer cylindrical portion having an outer cylindrical surface configured to contact the belt or the chain, and a radial intermediate portion between axial outer ends of the inner and outer cylindrical portions and an axial outer end of the outer cylindrical portion, wherein a ratio between a radial material thickness of the outer cylindrical portion and a radial material thickness of the inner cylindrical portion is strictly greater than 1.

A pulley device configured to support a belt of a chain tensioning idler or runner roller includes a bearing having a rotatable outer ring and a coaxial fixed inner ring and a pulley having at least one C-shaped pulley part that has an inner portion with an inner surface mounted on an outer cylindrical surface of the bearing outer ring, an outer cylindrical portion having an outer cylindrical surface configured to contact the belt or the chain, and a radial intermediate portion between axial outer ends of the inner and outer cylindrical portions and an axial outer end of the outer cylindrical portion, wherein a ratio between a radial material thickness of the outer cylindrical portion and a radial material thickness of the inner cylindrical portion is strictly greater than 1.

A belt pulley structure of an engine is provided to prevent abnormal noise from generating between a belt pulley and a torsional vibration damper. The belt pulley structure includes a stepped portion that is formed in a shape that blocks a cavity in a radial direction thereof. The cavity is formed at a portion where a belt pulley and a torsional vibration damper face each other.

A belt pulley structure of an engine is provided to prevent abnormal noise from generating between a belt pulley and a torsional vibration damper. The belt pulley structure includes a stepped portion that is formed in a shape that blocks a cavity in a radial direction thereof. The cavity is formed at a portion where a belt pulley and a torsional vibration damper face each other.

A power transmission device including a housing and a ball screw device including a nut, a screw shaft, and a plurality of balls. The device includes a pulley device including a driving pulley configured to be driven by receiving power transmitted from a power source, a driven pulley fixed to the nut, and a belt wound around outer peripheral surfaces of the driving pulley and the driven pulley. The device also includes a first bearing and a second bearing disposed between the housing and the nut in a center axis direction parallel with a center axis of the nut; and a preload applying member configured to apply preloads to the first bearing and the second bearing. The first bearing and the second bearing are respectively disposed on both sides of the driven pulley to be a face-to-face combination, and each of the first bearing and the second bearing includes an outer ring engaged with the housing.