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 at least includes a bottom rubber layer. A rubber composition for forming the bottom rubber layer contains a rubber component, cellulose fine fibers, and short fibers. The cellulose fine fibers have an average diameter from 1 nm to 200 nm, and the rubber composition contains 0.5 parts by mass or more of the cellulose fine fibers relative to 100 parts by mass of the rubber component. The short fibers have an average diameter from 5 m to 30 m, and the rubber composition contains 1 part by mass or more of the short fibers relative to 100 parts by mass the rubber component.

A power transmission belt at least includes a bottom rubber layer. A rubber composition for forming the bottom rubber layer contains a rubber component, cellulose fine fibers, and short fibers. The cellulose fine fibers have an average diameter from 1 nm to 200 nm, and the rubber composition contains 0.5 parts by mass or more of the cellulose fine fibers relative to 100 parts by mass of the rubber component. The short fibers have an average diameter from 5 m to 30 m, and the rubber composition contains 1 part by mass or more of the short fibers relative to 100 parts by mass the rubber component.

A drive belt having a main body formed of an elastomeric material, preferably a v-belt or v-ribbed belt, the drive belt including a top layer as belt backing, a power transmission zone having two or more tensile strands as strength members, and also a substructure optionally provided with some profiling preferably having a v-shape or a v-rib profile. The strength members are formed of cords made of mutually twisted plies (final twist), the plies being in turn twisted out of individual yarns (first twist). The cords consist essentially of polyethylene terephthalate (PET) and of two plies, the number of turns introduced into the plies twisted into a cord (final twist) and the number of turns introduced into the yarns twisted into a ply (first twist) differing by not more than 10 turns per meter (t/m).

A drive belt having a main body formed of an elastomeric material, preferably a v-belt or v-ribbed belt, the drive belt including a top layer as belt backing, a power transmission zone having two or more tensile strands as strength members, and also a substructure optionally provided with some profiling preferably having a v-shape or a v-rib profile. The strength members are formed of cords made of mutually twisted plies (final twist), the plies being in turn twisted out of individual yarns (first twist). The cords consist essentially of polyethylene terephthalate (PET) and of two plies, the number of turns introduced into the plies twisted into a cord (final twist) and the number of turns introduced into the yarns twisted into a ply (first twist) differing by not more than 10 turns per meter (t/m).

A belt for drive systems includes: an elastic and flame-retardant belt body made from a polymeric material and at least one flame retardant additive, the belt body having a cover layer as a belt back and a substructure which has a force transmission zone; and a tension member embedded in the belt body, wherein the belt body is partially or completely provided with a coating, which coating is single- or multi-layered.

A belt for drive systems includes: an elastic and flame-retardant belt body made from a polymeric material and at least one flame retardant additive, the belt body having a cover layer as a belt back and a substructure which has a force transmission zone; and a tension member embedded in the belt body, wherein the belt body is partially or completely provided with a coating, which coating is single- or multi-layered.

A pulley contacting portion of a friction transmission belt is made of a rubber composition containing an EPDM mixture as a rubber component. The EPDM mixture as the rubber component includes a first EPDM with an ethylene content of 67% by mass or more and a second EPDM with an ethylene content of 57% by mass or less. A content of the second EPDM in the EPDM mixture is larger than a content of the first EPDM in the EPDM mixture. An average ethylene content of the EPDM mixture is 54% by mass or more and 59% by mass or less.

Provided is a method for producing a V-ribbed belt having a plurality of V-shaped ribs extending in a longitudinal direction and arranged in a width direction. The method includes: setting a shaped structure having a plurality of ridges arranged adjacent to one another in a belt mold including a plurality of compressed rubber layer-shaping grooves arranged adjacent to one another on an inner peripheral surface of the mold; molding a belt slab by crosslinking the shaped structure set in the mold, while compressed rubber layer-forming portions face radially outward and are fitted in the compressed rubber layer-shaping grooves, the compressed rubber layer-forming portions comprised of a surface rubber layer and a core rubber layer which are to constitute surface and inner portions, respectively; and cutting the belt slab into ring-shaped pieces having two or more of the compressed rubber layer-forming portions.

Provided is a method for producing a V-ribbed belt having a plurality of V-shaped ribs extending in a longitudinal direction and arranged in a width direction. The method includes: setting a shaped structure having a plurality of ridges arranged adjacent to one another in a belt mold including a plurality of compressed rubber layer-shaping grooves arranged adjacent to one another on an inner peripheral surface of the mold; molding a belt slab by crosslinking the shaped structure set in the mold, while compressed rubber layer-forming portions face radially outward and are fitted in the compressed rubber layer-shaping grooves, the compressed rubber layer-forming portions comprised of a surface rubber layer and a core rubber layer which are to constitute surface and inner portions, respectively; and cutting the belt slab into ring-shaped pieces having two or more of the compressed rubber layer-forming portions.