Abstract: In prior stern drive marine propulsion systems, power is transmitted through an arrangement of clutches, bevel gears and shafts to the propeller located below the water surface. This restricts the amount of torque which can be transmitted particularly for large commercial boats. The present invention therefore provides an outdrive designed to surpass the horsepower and torque limitations set by current state-of-the-art units. In order to meet these objectives the outdrive was designed to incorporate a multi-strand roller chain drive, replacing the conventional bevel gear arrangement. Using a chain drive in this application serves to increase durability of the outdrive, while keeping the outercasing very streamlined.

Abstract: A marine drive for coupling a marine engine drive ring to a transmission drive shaft. A spider drive engages the drive ring and is provided with a plurality of rubber-cushioned trapezoidal lugs. The drive shaft is held in the spider drive by a central locking hub which is drawn tightly onto the drive shaft due to the tapered aperture in the spider drive. Wear-causing slippage of the drive shaft is thereby reduced.