Twin propeller marine propulsion unit

摘要

A twin propeller marine propulsion unit for a watercraft. A vertical drive shaft operably connected to the engine is journaled for rotation in a lower gear case and carries a beveled pinion that drives a pair of coaxial bevel gears. An inner propeller shaft and an outer propeller shaft are mounted concentrically in the lower torpedo-shaped section of the gear case and each propeller shaft carries a propeller. To provide forward movement for the watercraft, a sliding clutch, is moved in one direction to operably connect a first of the bevel gears with the inner propeller shaft to thereby drive the rear propeller. When the engine speed reaches a pre-selected elevated value, a hydraulically operated multi-disc clutch is actuated to operably connect the second of the bevel gears to the outer propeller shaft, to thereby drive the second propeller in the opposite direction. With this construction only a single propeller is driven at low engine speeds and the second propeller is driven when the engine speed reaches the pre-selected value.