Patent ID: 6446996
Filing Date: 2002-09-10
Classification: B62K

Abstract:
A frame structure of a motorcycle comprising:a main pipe extending from a head pipe toward a rear of the motorcycle and passing above an engine; and a pivot frame attached at an upper end side to a rear end of said main pipe and extending downwardly to support a front end of a swing arm capable of swinging movement, said pivot frame including: a pair of right and left pivot plates which pivotally support said swing arm, said pivot plates being forged from an aluminum alloy, each of said pivot plates including a plurality of ribs separated by recesses; and an upper cross member attaching the upper ends of said pivot plates together, said upper cross member being provided with a cross arm member extending laterally, attaching the upper end of said pivot plates to right and left ends of said cross arm member, said upper cross member being made from an aluminum alloy aid formed as one body with a mounting boss for a rear cushion unit, each of said pivot plates further comprising a first connecting recess at an upper end thereof for receiving fitting projections located at distal ends of said cross arm member, each said first connecting recess having an approximately rectangular configuration formed by an upper portion of said pivot plate and an inner one of said ribs, wherein said first connecting recesses guide and stabilize said fitting projections to fit into the approximately rectangular configuration of the first connecting recesses to facilitate permanent connection by welding.