Patent ID: 7494391

Claim:
An outboard motor comprising an engine and a propulsion unit, the propulsion unit comprising a drive shaft driven by the engine, a bevel gear mechanism, a propeller shaft driven by the drive shaft via the bevel gear mechanism, a lower casing adapted to support the propeller shaft, bevel gear mechanism, and drive shaft, the propeller shaft having a projection projecting generally rearward from the lower casing, a propeller shaft bearing for rotatably supporting the propeller shaft generally proximate the propeller shaft projection, and a lubricant circulation system adapted to circulate lubricant between the propeller shaft bearing and the bevel gear mechanism, the lubricant circulation system comprising a lubricant passage extending axially within the propeller shaft from a bevel gear mechanism attachment part of the propeller shaft to an axial terminus proximate to the propeller shaft bearing, the lubricant passage further extending radially within the propeller shaft from the axial terminus to a downstream opening at or adjacent the propeller shaft bearing, wherein the lubricant circulation system is adapted to circulate lubricant through the lubricant passage from the bevel gear mechanism to the propeller shaft bearing, wherein an upstream opening of the lubricant passage is provided in the bevel gear mechanism attachment part of the propeller shaft, and wherein the lubricant circulation system additionally comprises a return passage formed in a gap between the propeller shaft and an inner peripheral wall of a propeller shaft bore in the lower casing and extending from the downstream opening of the lubricant passage to the bevel gear mechanism attachment part.