Power unit for vehicle

A power unit for a vehicle, said power unit comprising:

• a crankcase;
• a crankshaft disposed in the crankcase;
• a first main shaft, a second main shaft and a countershaft that are rotatably supported by said crankcase with their axes being parallel to each other;
• a plurality of multispeed gears that are selectively established and provided among the first main shaft, the second main shaft and the countershaft;
• a primary reduction gear mechanism comprising a single driving gear arranged on said crankshaft, and operable to transmit rotary power from the crankshaft to the first and second main shafts;
• and
• first and second clutches that are operable to selectively transmit or interrupt a transfer of rotary power from the primary reduction gear mechanism to the first and second main shafts, said first and second clutches disposed at ends of the first and second main shafts, respectively,
• wherein the primary reduction gear mechanism further comprises:
• a first driven gear that is supported by the first main shaft for relative rotation therewith at a position adjacent to the first clutch, and that meshes with the driving gear;
• an intermediate driving gear integrally formed with said first driven gear so as rotate therewith;
• an idle gear that meshes with the intermediate driving gear, and that is supported by the countershaft for relative rotation therewith;
• and
• a second driven gear that is supported by the second main shaft for relative rotation therewith, and that meshes with the idle gear,
• wherein the first clutch is arranged between the first driven gear and first main shaft, and
• wherein the second clutch is arranged between the second driven gear and the second main shaft.

A power unit for a motorcycle, said power unit comprising

• a crankcase;
• a crankshaft disposed in the crankcase;
• a first main shaft, a second main shaft and a countershaft that are rotatably supported by said crankcase with their axes being parallel to each other;
• a plurality of multispeed gears that are selectively established and provided among the first main shaft, the second main shaft and the single countershaft;
• a primary reduction gear mechanism comprising:
• a driving gear arranged on the crankshaft;
• said driving gear being operable to transmit rotary power from the crankshaft to the first and second main shafts;
• and
• a first driven gear that is supported by the first main shaft for relative rotation therewith at a position adjacent to the first clutch, and that meshes with the driving gear;
• an intermediate driving gear integrally formed with said first driven gear as a one-piece structure;
• an idle gear that meshes with the intermediate driving gear, and that is supported by the countershaft for relative rotation therewith;
• and
• a second driven gear that is supported by the second main shaft for relative rotation therewith, and that meshes with the idle gear;
• and
• first and second clutches that are operable to selectively transmit or interrupt a transfer of rotary power from the primary reduction gear mechanism to the first and second main shafts, said first and second clutches being disposed at ends of the first and second main shafts, respectively,
• wherein the first clutch is provided between the first driven gear and first main shaft, and
• wherein the second clutch is provided between the second driven gear and the second main shaft.