Abstract: A toothed belt is provided with toothed portions arranged at a regular pitch in a belt length direction. A belt body is made of a rubber composition containing, as a main ingredient of a rubber component, ethylene-?-olefin elastomer having an ethylene content of 44% by mass to 66% by mass. A reinforcing fabric is adhered to a surface of the belt body on a toothed side, with a reinforcing fabric adhesion coat interposed between the reinforcing fabric and the belt body. The reinforcing fabric adhesion coat is made of a rubber composition containing hydrogenated nitrile-butadiene rubber as a main ingredient of a rubber component.

Abstract: A toothed belt is provided with toothed portions arranged at a regular pitch in a belt length direction. A belt body is made of a rubber composition containing, as a main ingredient of a rubber component, ethylene-?-olefin elastomer having an ethylene content of 44% by mass to 66% by mass. A reinforcing fabric is adhered to a surface of the belt body on a toothed side, with a reinforcing fabric adhesion coat interposed between the reinforcing fabric and the belt body. The reinforcing fabric adhesion coat is made of a rubber composition containing hydrogenated nitrile-butadiene rubber as a main ingredient of a rubber component.

Abstract: A toothed belt includes: a back portion; and a plurality of helical teeth provided on an inner periphery of the back portion and disposed at a fixed pitch in a belt longitudinal direction. An angle ? between a tooth trace direction of the helical teeth and a belt lateral direction is in a range of 7 degrees to 10 degrees, both inclusive. A ratio A of a thickness tb of the back portion to a tooth height hb of the helical teeth, which is given by A=100×tb/hb, is in a range of 120% to 240%, both inclusive.

Abstract: A friction drive belt (B) includes short fibers (14) and carbon black (18) both scattered so as to be exposed at a surface of at least a contact part (13) of a rubber belt body (10) with a pulley. The short fibers (14) include short, high modulus fibers made of polymers having a main chain which does not contain an aromatic compound and having an initial tensile resistance, measured according to JIS L 1013, of equal to or greater than 100 cN/dtex, and the carbon black (18) contain large-particle-diameter carbon black having an iodine absorption, measured according to JIS K 6217-1, of equal to or less than 40 g/Kg, and/or a specific surface area, measured by nitrogen adsorption according to JIS K 6217-2, of equal to or less than 40 m2/g.

Abstract: A toothed belt includes: a back portion; and a plurality of helical teeth provided on an inner periphery of the back portion and disposed at a fixed pitch in a belt longitudinal direction. An angle ? between a tooth trace direction of the helical teeth and a belt lateral direction is in a range of 7 degrees to 10 degrees, both inclusive. A ratio A of a thickness tb of the back portion to a tooth height hb of the helical teeth, which is given by A=100×tb/hb, is in a range of 120% to 240%, both inclusive.

Abstract: A power transmission belt (10) includes: a belt body (11) including a part (14) which is in contact with a flat pulley and which is made of a rubber composition containing an ethylene-?-olefin elastomer with an ethylene content of less than or equal to 60% by mass as raw rubber. The rubber composition forming the contact part (14) with the flat pulley has a storage modulus of 20-60 MPa at 25° C. and a storage modulus of 12 MPa or more at 100° C., short fibers are not blended into the rubber composition, and the grain direction of the rubber composition corresponds to a belt lengthwise direction.

Abstract: A friction drive belt includes: an adhesion rubber layer having a core wire embedded therein so as to form a helical pattern having a pitch in a lateral direction of the belt; a compression rubber layer provided on a surface of the adhesion rubber layer located on an inner side of the belt, and serving as a portion that is to contact pulleys, and a backing rubber layer provided on a surface of the adhesion rubber layer located on an outer side of the belt, and serving as a back portion of the belt. A ratio of tensile stress at 10% elongation of a rubber composition forming the adhesion rubber layer to that of a rubber composition forming the backing rubber layer is 1.77 or more, as measured in a longitudinal direction of the belt at an ambient temperature of 25° C. according to JIS K 6251.

Abstract: A friction drive belt includes: an adhesion rubber layer having a core wire embedded therein so as to form a helical pattern having a pitch in a lateral direction of the belt; a compression rubber layer provided on a surface of the adhesion rubber layer located on an inner side of the belt, and serving as a portion that is to contact pulleys, and a backing rubber layer provided on a surface of the adhesion rubber layer located on an outer side of the belt, and serving as a back portion of the belt. A ratio of tensile stress at 10% elongation of a rubber composition forming the adhesion rubber layer to that of a rubber composition forming the backing rubber layer is 1.77 or more, as measured in a longitudinal direction of the belt at an ambient temperature of 25° C. according to JIS K 6251.

Abstract: A power transmission belt (10) includes: a belt body (11) including a part (14) which is in contact with a flat pulley and which is made of a rubber composition containing an ethylene-?-olefin elastomer with an ethylene content of less than or equal to 60% by mass as raw rubber. The rubber composition forming the contact part (14) with the flat pulley has a storage modulus of 20-60 MPa at 25° C. and a storage modulus of 12 MPa or more at 100° C., short fibers are not blended into the rubber composition, and the grain direction of the rubber composition corresponds to a belt lengthwise direction.

Abstract: Short fibers 6a protruded from side faces 5a of rubber ribs 5 are thermal contracted by frictional heat by belt slip of the rubber rib side faces 5 on a V groove face of a pulley. This allows the short fibers 6a to be buried in rubber ribs 5.

Abstract: In a method for estimating an entrance angle of a V-ribbed belt from a flat pulley to a V-ribbed pulley, the entrance angle is estimated easily at a stage of pulley layout design. The V-ribbed belt 10 forms a track which enters at an entrance angle of approximately zero degree (substantially perpendicular to a plane that includes an axis 3a of rotation) into the flat pulley 3, is wound along the outer peripheral face of the flat pulley 3 without deviating in the axial direction thereof, and extends substantially linearly from a winding end point c at the flat pulley 3 to a winding start point d at a drive pulley 1. The entrance angle ? of the V-ribbed belt 10 from the flat pulley 3 to the drive pulley 1 is obtained on the basis of the track of the V-ribbed belt by, for example, a three-dimensional CAD or the like.

Abstract: A friction drive belt (B) includes short fibers (14) and carbon black (18) both scattered so as to be exposed at a surface of at least a contact part (13) of a rubber belt body (10) with a pulley. The short fibers (14) include short, high modulus fibers made of polymers having a main chain which does not contain an aromatic compound and having an initial tensile resistance, measured according to JIS L 1013, of equal to or greater than 100 cN/dtex, and the carbon black (18) contain large-particle-diameter carbon black having an iodine absorption, measured according to JIS K 6217-1, of equal to or less than 40 g/Kg, and/or a specific surface area, measured by nitrogen adsorption according to JIS K 6217-2, of equal to or less than 40 m2/g.

Abstract: It is an object of the present invention to improve the long-term durability of a power transmission belt. There is provided a power transmission belt characterized in that it includes a rubber layer that is formed of a cross-linked rubber composition and extends in a belt lengthwise direction, and core wires that is adhered to the rubber layer and embedded therein in the belt lengthwise direction, in which the rubber layer with the core wires embedded therein is formed to have a tensile stress of 1.1 to 1.7 MPa when the rubber layer is stretched in the belt lengthwise direction by 10% at 125° C.

Abstract: In a method for estimating an entrance angle of a V-ribbed belt from a flat pulley to a V-ribbed pulley, the entrance angle is estimated easily at a stage of pulley layout design. The V-ribbed belt 10 forms a track which enters at an entrance angle of approximately zero degree (substantially perpendicular to a plane that includes an axis 3a of rotation) into the flat pulley 3, is wound along the outer peripheral face of the flat pulley 3 without deviating in the axial direction thereof, and extends substantially linearly from a winding end point c at the flat pulley 3 to a winding start point d at a drive pulley 1. The entrance angle ? of the V-ribbed belt 10 from the flat pulley 3 to the drive pulley 1 is obtained on the basis of the track of the V-ribbed belt by, for example, a three-dimensional CAD or the like.

Abstract: Short fibers 6a protruded from side faces 5a of rubber ribs 5 are thermal contracted by frictional heat by belt slip of the rubber rib side faces 5 on a V groove face of a pulley. This allows the short fibers 6a to be buried in rubber ribs 5.

Abstract: In a belt transmission system including a combination of a V-belt for heavy load transmission and V-pulleys as variable speed pulleys, the surface roughness of a pulley groove of each V-pulley is set within the range from 0.5 to 3.0 &mgr;m to reduce energy generated when the V-belt and the V-pulleys are interfered with each other thereby reducing production of running noise during belt running.

Abstract: The tension member for a belt of this invention is made from a glass cord. First twist yarns of this glass cord are obtained by paralleling and twisting a plurality of fiber bundles, each including a large number of glass filaments, by a predetermined first twist number. The fiber bundles are previously soaked with a treatment liquid including a mixture of rubber latex and an initial condensation product of resorcinol and formalin as a main component and then heated. The glass cord is fabricated by paralleling a predetermined number of the first twist yarns and twisting them by a predetermined final twist number, so as to squeeze and substantially eliminating spaces among the first twist yarns. Accordingly, the belt including this glass cord as the tension member can achieve good water resistance because externally intruding water is prevented from being held within the belt.