Heavy duty power transmission v-belt

Abstract

In a heavy duty power transmission V-belt B formed by engaging tension membersandwith a plurality of blocks, . . . , to prevent as much as possible each blockfrom producing failure at the high-speed running of the belt, a fitting partof each blockhas an indentformed by upwardly recessing a portion of a resin partlocated between an upper ridgeand an innermost abutment surfaceof the fitting part. Thereby, no edge exists between the innermost abutment surfaceand the upper ridgeso that stress can be distributed. This prevents the occurrence of a crack in the resin partdue to stress concentration on the edge, the occurrence of a crack in a reinforcementof each blockbeginning at the leading end of the crack in the resin part, and in turn the fracture of an upper beamof the reinforcement, thereby providing enhanced resistance against failure of the block. Furthermore, even when a shape-retaining rubber layerof the tension memberthermally expands, the amount of expansion thereof is released into the indent. This prevents early introduction of permanent deformation of the shape-retaining rubber layerand occurrence of an excessive force in the blockdue to a compressive force produced in the fitting part, which prevents the occurrence of wobbling between the tension memberand each block. Furthermore, it can be prevented that the shape-retaining rubber layerproduces heat because of excessive deformation and in turn causes thermal expansion and thermal deterioration.