Patent ID: 8147285

Claim:
A marine vessel propulsion unit comprising: an engine; a drive shaft arranged to be rotated by the engine; a propeller shaft to which rotation of the drive shaft is transmitted, the propeller shaft extending in a direction perpendicular or substantially perpendicular to the drive shaft; a propeller arranged to be rotated together with the propeller shaft; an intermediate shaft arranged on a central rotation axis of the propeller shaft or an extension of the central rotation axis, the intermediate shaft arranged to transmit rotation between the drive shaft and the propeller shaft; a gear mechanism including a drive gear integrally joined to a lower end of the drive shaft, and a driven gear engaged with the drive gear so as to be rotated about the central rotation axis of the propeller shaft to transmit the rotation of the drive shaft to the intermediate shaft; a first reduction gear mechanism arranged on the central rotation axis of the propeller shaft or the extension of the central rotation axis, the first reduction gear mechanism arranged to decelerate the rotation of the intermediate shaft so as to transmit the decelerated rotation to the propeller shaft both in a forward propulsion and a backward propulsion of the marine vessel propulsion unit; and a lower case arranged to house a portion of the drive shaft, the drive gear, the driven gear, and the first reduction gear mechanism; wherein the first reduction gear mechanism is arranged on the central rotation axis between the driven gear and the propeller.