Power transmission casing apparatus in motorized two-wheeled vehicle

Claim 1

A power transmission casing apparatus in a motorized two-wheeled vehicle comprising: a case main body extending from one lateral side of an internal combustion engine to one lateral side of a rear wheel positioned rearwardly of said engine, said case main body being partitioned into front and rear casing sections and having a longitudinally extending lateral wall, said rear casing section rotatably supporting a wheel axle of said rear wheel and having a recessed portion for partially housing a reduction gear means which includes said wheel axle, an unput shaft, and a gear train operatively interconnecting said input shaft to said wheel axle, a transmission cover member sealingly engaging at least a portion of the lateral wall of said case main body to cover the recessed portion thereof in a fluid tight manner; and a V-belt cover sealingly engaging said case main body; said case main body including on the lateral wall thereof transverse projections which extend to such a position that said transmission cover member and said V-belt cover engage the lateral wall of said case main body; said casing apparatus housing V-belt means including a rear pulley on said input shaft, a forward pulley on an output shaft of said engine and a V-belt operatively connecting said pulleys, each of said pulleys having a circumferential periphery wherein said reduction gear means are positioned closer to said rear wheel than said V-belt means, and a centrifugal clutch is provided on an outer end of said input shaft furthermost from said rear wheel via said reduction gear means and said V-belt means; wherein said transmission cover member extends to enclose said reduction gear means to form a wet type chamber to hold a lubricant to immerse said reduction gear means; and wherein said V-belt cover extends from beyond the forwardmost portion of the periphery of said forward pulley to beyond the rearmost portion of the periphery of said rear pulley to enclose said V-belt means for form a dry type chamber; said case main body being integrally provided at the front casing section thereof with an engine casing to form a power unit with said transmission cover member and said V-belt cover, the power unit being swingably mounted on the vehicle body; and said V-belt cover and said transmission cover member being both on the same side of said case main body in an opposed relation to said engine and said rear wheel.