Abstract: Compositions for material layers suitable for use in power transmission belts are described. The composition includes millable polyurethane, such as polyester-based millable polyurethane or polyether-based millable polyurethane, such that material layers formed from the composition are solid but pliable. The disclosed material layers can be used to form the main body portion of power transmission belts, such as synchronous belts, V-belts, and micro-V belts.

Abstract: A synchronous belt drive system having: a synchronous belt with a tensile cord of high-modulus fiber such as glass, carbon, PBO, or aramid; a driver sprocket and at least one driven sprocket, at least one of which is an obround sprocket; and a tensioner having: a base having a cylindrical portion extending axially with a radially outer surface and a receiving portion, an eccentric arm pivotally engaged with the radially outer surface, a torsion spring disposed within the receiving portion, the torsion spring applying a biasing force to the eccentric arm, and a pulley journalled to the eccentric arm. Preferably, no one of the eccentric arm, pulley, or torsion spring is axially displaced along an axis A-A from the others. The obround sprocket has a toothed surface and at least one linear portion disposed between two arcuate portions having a constant radius, the linear portion having a predetermined length.

Abstract: A synchronous belt with a tensile member layer having a tensile member embedded in an elastomeric body; a toothed surface with a plurality of regularly spaced, transverse teeth protruding from the body; and a jacket covering the toothed surface; wherein the teeth comprise a plurality of fabric insert layers that increase the stiffness of the tooth, the insert layers separated from each other by layers of an elastomer composition. The layers may be oriented parallel to the tensile member layer, perpendicular to the tensile member, or following the contour of the tooth. The layers may be a single piece of fabric folded into layers, or separate pieces of fabric.

Abstract: A synchronous belt having a tensile member layer with a tensile member embedded in an elastomeric body, a toothed surface with a plurality of regularly spaced, transverse teeth protruding from the body, a jacket covering the toothed surface, and a unidirectional fabric layer suspended in the belt between the jacket and the tensile member layer and following the approximate contour of the jacket.

Abstract: A synchronous belt drive system having: a synchronous belt with a tensile cord of high-modulus fiber such as glass, carbon, PBO, or aramid; a driver sprocket and at least one driven sprocket, at least one of which is an obround sprocket; and a tensioner having: a base having a cylindrical portion extending axially with a radially outer surface and a receiving portion, an eccentric arm pivotally engaged with the radially outer surface, a torsion spring disposed within the receiving portion, the torsion spring applying a biasing force to the eccentric arm, and a pulley journalled to the eccentric arm. Preferably, no one of the eccentric arm, pulley, or torsion spring is axially displaced along an axis A-A from the others. The obround sprocket has a toothed surface and at least one linear portion disposed between two arcuate portions having a constant radius, the linear portion having a predetermined length.

Abstract: A synchronous belt with a tensile member layer having a tensile member embedded in an elastomeric body; a toothed surface with a plurality of regularly spaced, transverse teeth protruding from the body; and a jacket covering the toothed surface; wherein the teeth comprise a plurality of fabric insert layers that increase the stiffness of the tooth, the insert layers separated from each other by layers of an elastomer composition. The layers may be oriented parallel to the tensile member layer, perpendicular to the tensile member, or following the contour of the tooth. The layers may be a single piece of fabric folded into layers, or separate pieces of fabric.

Abstract: A synchronous belt having a tensile member layer with a tensile member embedded in an elastomeric body, a toothed surface with a plurality of regularly spaced, transverse teeth protruding from the body, a jacket covering the toothed surface, and a unidirectional fabric layer suspended in the belt between the jacket and the tensile member layer and following the approximate contour of the jacket.