Torsional shock absorber with consecutive step-wise elastic resistance to relative rotation

A torsional shock absorber, comprising:

• a primary part adapted to be coupled with a rotatable flywheel of a motor and rotated therewith;
• a secondary part adapted to be coupled with a rotatable input shaft of a boat transmission, said secondary part being rotatable relative to said primary part only through a limited angle;
• compressible first and second resilient means for resisting said relative rotation of said primary part and said secondary part and mounting means for orienting said first and second resilient means symmetrically with respect to an axis of rotation of said primary part and said secondary part;
• first means for effecting said second resilient means becoming active only after said first resilient means has become active, said second resilient means having a greater hardness and, therefore, requiring a greater force to compress it than for said first resilient means;
• at least one friction element arranged between said primary part and said secondary part for hindering said relative rotation;
• and
• said first resilient means including bearing means directly, relatively movably, supported on at least one inclined surface extending in a peripheral direction, said surface being provided on at least one of said primary part and said secondary part so that said bearing means will move along said inclined surface to increasingly compress said first resilient means in response to increasing relative rotation between said primary part and said secondary part to increasingly resist said relative rotation, said second resilient means also defining a limit and thereby a finite size for said limited angle, said second resilient means thereby preventing further relative rotation between said primary part and said secondary part beyond said limited angle.