Torsionally twisting propeller drive sleeve

In a marine drive comprising a propeller with a hub, and an axially extending propeller shaft, a shock absorbing drive sleeve mounting said propeller hub to said propeller shaft and comprising an inner diameter portion keyed to and engaging said propeller shaft in drive relation, a first outer diameter portion radially aligned with said inner diameter portion, a second outer diameter portion axially spaced from said inner diameter portion and said first outer diameter portion and keyed to and engaging said propeller hub in driving relation, wherein said drive sleeve and said propeller hub are configured relative to each other such that said second outer diameter portion snugly engages said propeller hub, and said first outer diameter portion may at least partially rotate relative to said propeller hub in response to rotation of said propeller shaft drivingly engaging said inner diameter portion, such that when said propeller strikes an object, the shock is absorbed by torsional twisting of said drive sleeve wherein said inner diameter portion and said first outer diameter portion continue to rotate to a further rotated position than said second outer diameter portion, said drive sleeve being composed of a plastic material providing torsional twisting angular rotation at a first spring rate less than 100 lb. ft. per degree from 0.degree. to 5.degree. rotation, a second higher spring rate beyond 5.degree. rotation, and supporting over 1,000 lb. ft. torque before failure.

In a marine drive comprising a propeller with a hub, and an axially extending propeller shaft, a shock absorbing drive sleeve in said propeller hub and mounting said propeller hub to said propeller shaft and comprising an inner diameter portion keyed to and engaging said propeller shaft in driven relation, a first outer diameter portion radially aligned with said inner diameter portion, said first outer diameter portion and said propeller hub being in spaced but keyed relation permitting limited rotation of said first outer diameter portion through a given angle relative to said propeller hub, followed by an interference fit and co-rotation thereof, a second outer diameter portion axially spaced from said first outer diameter portion and keyed to and engaging said propeller hub in driving relation, wherein said drive sleeve and said propeller hub are configured relative to each other such that said second outer diameter portion snugly engages said propeller hub, and said first outer diameter portion may at least partially rotate relative to said propeller hub in response to rotation of said propeller shaft drivingly engaging said inner diameter portion, such that when said propeller strikes an object, the shock is absorbed by torsional twisting of sad drive sleeve wherein said inner diameter portion and said first outer diameter portion continue to rotate to a further rotated position than said second outer diameter portion, said first outer diameter portion rotating through said given angle to said further rotated position whereupon said first outer diameter portion engages said propeller hub in said interference fit whereafter said first outer diameter portion and said propeller hub rotate together wherein said drive sleeve has an overall axial length, and said inner diameter portion engaging said propeller shaft has an axial length which is 40% to 50% of said overall axial length.