Oil circulating system for marine propulsion gear case

Abstract

A marine propulsion drive mounted to a boat transom includes a vertical drive shaft and a horizontal propeller shaft coupled by a pair of bevel gears in an oil filled lower housing unit. The vertical shaft is supported in vertically spaced bearings, one of which is immediately adjacent the upper wall of the bevel gear and the other of which is spaced upwardly therefrom. A shift member is selectably positioned through a shift linkage including a vertically extending shift rod which projects upwardly through an appropriate opening in the housing. A lateral passageway is provided immediately adjacent the upper bearing which extends laterally and downwardly to the shift passageway. An oil circulating passageway is formed having an inlet end in the upper wall of the lower housing adjacent to the upper face of the drive bevel gear and an outlet end terminating between the bearings. The inlet of the circulating passageway is laterally offset from the common plane through the vertical drive shaft and the propeller shaft and therefore offset with respect to the full mating position of the gear teeth of the corresponding set of bevel gears. The passageway inlet is particularly located overlying the outer peripheral portion of one of the drive gears on the vertical shaft and to the upwardly moving side thereof. The inlet is further located also generally overlying the outermost edge of the mating driven bevel gear on the propeller shaft. Oil flows continuously upwardly through and over the ball bearing unit and returns downwardly through the shift rod opening in the lower unit housing to the lower portion of the gear casing.