Abstract: A clutch mechanism includes forward and reverse driving gears rotatably mounted on the input shaft which has first and second oppositely threaded driving spiral threads thereon. First and second clutch elements threadedly engage the spiral threads on the input shaft. In the neutral position, the clutch elements rotate with the input shaft but when rotation is impeded, the spiral threads drive the clutch elements axially into engagement with the driving gears. An improved shift mechanism includes a yoke having two legs which extend over flanges on the clutch elements. A pin member moves the clutch elements upon axial movement of the shift linkage. Drag is provided for the yoke so that the flange of the clutch element is pinched between the pin member and the yoke to impede rotation of the clutch element. The shift mechanism engages and disengages the clutch smoothly and with the engine torque providing most of the force required for engagement and disengagement.

Abstract: An inboard-outboard drive is taught having an upper, approximately horizontal input shaft; an output shaft substantially parallel thereto for driving a propeller; and a vertically-oriented intermediate shaft coupled to the other shafts by suitable gearing. The upper and lower shafts are journaled in upper and lower housings, respectively. A tubular member disposed coaxially with the intermediate shaft couples the upper and lower housings, allowing the lower housing to rotate with respect to the upper housing. The tubular member is associated with a steering member opposite sides of which are coupled to ones of a pair of hydraulic cylinders disposed within the upper housing. In one embodiment the steering member comprises a pinion which is rotated by rack gears coupled to the hydraulic cylinders and adapted to slide back and forth in ways formed in the upper housing. In another embodiment, the steering member is a bellcrank keyed to the tubular member and coupled to the hydraulic cylinders by linkage arms.