Patent ID: 7845246

Claim:
A twin-clutch transmission in a power unit for a vehicle, in which power unit the power is transmitted to a gear transmission housed in a crankcase of an engine, via a primary reduction system and a clutch system, from an end portion of a crankshaft, wherein the clutch system includes a pair of hydraulic clutches respectively having clutch pistons; the gear transmission includes a first main shaft, which has a first end portion linked with a first one of the hydraulic clutches, and which is placed in parallel to the crankshaft, and also includes a second main shaft, which has a first end portion linked with a second one of the two hydraulic clutches, and which coaxially penetrates the first main shaft; a pair of hydraulic passages are concentrically formed inside the second main shaft to apply hydraulic pressure respectively to the clutch pistons of the hydraulic clutches and allowing operating fluid to be supplied from a second end side of the second main shaft, wherein the crankcase has first and second sidewalls on opposite sides thereof, and the clutch system is fixed to the first end portions of the first main shaft and the second main shaft, the first end portions being outside the first sidewall of the crankcase, the twin-clutch transmission further comprising: an inner supply pipe coaxially inserted into a center hole of the second main shaft, the inner supply pipe including a first end portion disposed in a vicinity of a closed end of the center hole placed within a width of the clutch system, which is outside the first sidewall, and an outer supply pipe inserted into the central hole while coaxially surrounding the inner supply pipe and having a first end portion in a vicinity of the first end portion of the inner supply pipe, wherein the inner supply pipe and the outer supply pipe each have a second end portion disposed outside of the second sidewall.