A rubber-reinforcing cord (12) of the present invention includes at least three strands. Each of the strands includes at least one filament bundle and a first coating provided to cover at least a portion of the surface of the filament bundle. The filament bundle consists essentially of aramid fiber filaments. The mass of the first coating is in the range of 14 to 25% with respect to the mass of the filament bundle. Each of the strands is given primary twists at a primary twisting rate of 50 to 100 twists/m. The at least three strands each given primary twists are assembled and given final twists at a final twisting rate of 120 to 200 twists/m.

In some embodiments, the present disclosure provides a composition comprising from 5 phr to 30 phr of a PEDM terpolymer having 1 to 10 wt % diene, 13 to 40 wt % ethylene, and 15 to 85 wt % propylene, based on the weight of the PEDM terpolymer. The composition further comprises from 70 phr to 95 phr of an ethylene-based copolymer comprising an ethylene content different than the first polymer, a C.sub.3 to C.sub.12 -olefin, and, optionally, one or more dienes.

An aqueous treatment agent for preparing a cord by treating an untreated yarn for a power transmission belt includes at least a first aqueous treatment agent. The first aqueous treatment agent contains an epoxy resin (A), a polycarbonate polyol (B), and a blocked polyisocyanate (C). The epoxy resin (A) may contain a bisphenol type epoxy resin (A1). The polycarbonate polyol (B) may contain a polycarbonate diol (B1). The blocked polyisocyanate (C) may contain at least one blocked polyisocyanate selected from the group consisting of an aliphatic polyisocyanate or derivatives thereof and an aromatic polyisocyanate and having a dissociation temperature of 120 C. to 180 C.

An aqueous treatment agent for preparing a cord by treating an untreated yarn for a power transmission belt includes at least a first aqueous treatment agent. The first aqueous treatment agent contains an epoxy resin (A), a polycarbonate polyol (B), and a blocked polyisocyanate (C). The epoxy resin (A) may contain a bisphenol type epoxy resin (A1). The polycarbonate polyol (B) may contain a polycarbonate diol (B1). The blocked polyisocyanate (C) may contain at least one blocked polyisocyanate selected from the group consisting of an aliphatic polyisocyanate or derivatives thereof and an aromatic polyisocyanate and having a dissociation temperature of 120 C. to 180 C.

A power transmission V-belt includes a tension member, an adhesion rubber layer in which at least part of the tension member is embedded, and a tension rubber layer and a compression rubber layer stacked via the adhesion rubber layer. A rubber hardness of the tension rubber layer is smaller than a rubber hardness of the compression rubber layer. In the adhesion rubber layer, a rubber hardness on a tension rubber layer side relative to the tension member is smaller than a rubber hardness on a compression rubber layer side.

A power transmission V-belt includes a tension member, an adhesion rubber layer in which at least part of the tension member is embedded, and a tension rubber layer and a compression rubber layer stacked via the adhesion rubber layer. A rubber hardness of the tension rubber layer is smaller than a rubber hardness of the compression rubber layer. In the adhesion rubber layer, a rubber hardness on a tension rubber layer side relative to the tension member is smaller than a rubber hardness on a compression rubber layer side.

The present invention relates to a V-ribbed belt in which a friction transmission surface of a compression rubber layer is coated with a knit fabric. The compression rubber layer is formed of the cured product of a rubber composition containing an ethylene--olefin elastomer and carbon black wherein the carbon black contains a soft carbon having a primary particle diameter of at least 40 nm and a hard carbon having a primary particle diameter of less than 40 nm. The ratio between the number of particles of the soft carbon and hard carbon is former/latter=3/97 to 25/75.

An uncrosslinked rubber shaped structure for belt production is placed in a belt mold with the uncrosslinked rubber shaped structure having a bent portion that is bent inward. A space inside the uncrosslinked rubber shaped structure is partitioned into a first space and a second space. The first space corresponds to a first shaped structure portion of the uncrosslinked rubber shaped structure, the first shaped structure portion including the bent portion. The second space corresponds to a second shaped structure portion of the uncrosslinked rubber shaped structure that is a portion of the uncrosslinked rubber shaped structure except the first shaped structure portion. An expansion member is expanded in the second space to press the second shaped structure portion toward the belt mold.

The present invention pertains to a friction transmission belt that includes a core cable. The core cable includes a cord comprising: a core yarn containing high elastic-modulus fibers; and a plurality of sheath yarns that are disposed around the core yarn and that contain low elastic-modulus fibers. The cord is twisted and the proportion of the average diameter of the sheath yarn to the average diameter of the core yarn is 0.2 to 0.4.

The present invention pertains to a friction transmission belt that includes a core cable. The core cable includes a cord comprising: a core yarn containing high elastic-modulus fibers; and a plurality of sheath yarns that are disposed around the core yarn and that contain low elastic-modulus fibers. The cord is twisted and the proportion of the average diameter of the sheath yarn to the average diameter of the core yarn is 0.2 to 0.4.