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.

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.

A frictional power-transmission belt having a frictional power-transmission surface covered with a composite fiber layer, in which the composite fiber layer includes a fiber member and an isocyanate compound, and the fiber member includes a cellulose-based fiber. In the frictional power-transmission belt, the isocyanate compound may have a proportion of 3 to 20 mass % in the composite fiber layer.

A frictional power-transmission belt having a frictional power-transmission surface covered with a composite fiber layer, in which the composite fiber layer includes a fiber member and an isocyanate compound, and the fiber member includes a cellulose-based fiber. In the frictional power-transmission belt, the isocyanate compound may have a proportion of 3 to 20 mass % in the composite fiber layer.

A power transmission belt is at least partially formed of a rubber composition. The rubber composition contains a rubber component, cellulose nanofibers, and carbon black. The amount of the cellulose nanofibers to be added is from 0.1 parts by mass to 20 parts by mass, relative to 100 parts by mass of the rubber component. The amount of the carbon black to be added is from 5 parts by mass to 80 parts by mass, relative to 100 parts by mass of the rubber component. The sum of the amount of the carbon black to be added and three times the amount of the cellulose nanofibers to be added is from 15 to 90.

A power transmission belt is at least partially formed of a rubber composition. The rubber composition contains a rubber component, cellulose nanofibers, and carbon black. The amount of the cellulose nanofibers to be added is from 0.1 parts by mass to 20 parts by mass, relative to 100 parts by mass of the rubber component. The amount of the carbon black to be added is from 5 parts by mass to 80 parts by mass, relative to 100 parts by mass of the rubber component. The sum of the amount of the carbon black to be added and three times the amount of the cellulose nanofibers to be added is from 15 to 90.

The present invention relates to a V-ribbed belt that includes carbon-fiber twisted cords as core wires, the V-ribbed belt having a tensile elasticity of 240-500 N/(mm.Math.%), and the core wire diameter of the core wires being 0.6-1.2 mm. The V-ribbed belt may have a tensile strength of 620 N/mm or more per 1 mm width of the belt.

The present invention relates to a V-ribbed belt that includes carbon-fiber twisted cords as core wires, the V-ribbed belt having a tensile elasticity of 240-500 N/(mm.Math.%), and the core wire diameter of the core wires being 0.6-1.2 mm. The V-ribbed belt may have a tensile strength of 620 N/mm or more per 1 mm width of the belt.

Drive belt having a belt rear side which is provided for driving auxiliary units, in particular V-ribbed belt, wherein the belt rear side is profiled and is preferably provided with an embossed profile, wherein the profile of the rear-side surface of the drive belt has a multiplicity of projections in the shape of truncated pyramids, the height h of which is less than 1 mm, and is preferably in macroscopic orders of magnitude where h0.2 mm, wherein the base areas A.sub.G of the projections in the shape of truncated pyramids have an area of 1.0 mm.sup.2 and the top surfaces A.sub.D have an area of <0.8 mm.sup.2.

Drive belt having a belt rear side which is provided for driving auxiliary units, in particular V-ribbed belt, wherein the belt rear side is profiled and is preferably provided with an embossed profile, wherein the profile of the rear-side surface of the drive belt has a multiplicity of projections in the shape of truncated pyramids, the height h of which is less than 1 mm, and is preferably in macroscopic orders of magnitude where h0.2 mm, wherein the base areas A.sub.G of the projections in the shape of truncated pyramids have an area of 1.0 mm.sup.2 and the top surfaces A.sub.D have an area of <0.8 mm.sup.2.