Four-wheel drive clutch

A selective drive clutch for automatically connecting a driven element to a drive element for conjoint coaxial rotation and for automatically disconnecting same when said drive element is not being driven, comprising:

• a first interlocking member mountable upon the driven member for rotational movement therewith;
• a second interlocking member mountable upon the drive element for rotational movement therewith and for axial movement relative thereto between retracted and extended positions;
• means carried by opposed end portions of said first and second interlocking members effective upon extension of the latter to interengage and effect a driving connection therebetween;
• first biasing means operatively associated with said second interlocking member normally biasing same into retracted position;
• and actuating means responsive to limited relative rotational movement between said drive and driven elements for effecting an axial shift of said second interlocking member between its extended and retracted positions, said means including inner and outer grooved cam rings, at least two equiangularly-spaced cam followers in the form of balls seated in the grooves and interconnecting the cam rings for limited relative axial and rotational movement in coaxial circumferentially-spaced relation, and braking means having a fixed friction surface engaging said inner cam ring effective to yieldably retard rotation thereof, the outer of said cam rings being movable both axially and rotarially with said second interlocking member on the end thereof remote from said first interlocking member, the grooves in said cam rings comprising an opposed pair of generally V-shaped tracks for each ball facing opposite one another in axially-divergent overlapped relation, said paired ball tracks when interconnected by a ball in side-by-side relation being responsive to rotational movement of the drive element in either direction while the inner cam ring is yieldably restrained against rotation to move said tracks into an overlapped end-to-end relation operative to move the outer cam ring axially from a retracted into an extended position thereby extending the second interlocking member associated therewith into interengaged driving relation with the first interlocking member, and said balls when seated within the overlapped ends of said paired tracks cooperating therewith to overcome the braking action of the braking means yieldably retarding rotation of said inner cam ring while defining a driving connection between the latter and said outer cam ring causing them to rotate as a unit upon continued rotation of said drive element in the same direction, said ball tracks and ball also cooperating in response to reversal of said drive element while the first and second interlocking elements remain interlocked and with said tracks disposed in end-to-end relation to momentarily retract and extend said outer cam ring as well as rotate same relative to said inner cam ring while the latter is restrained against rotational movement thereby placing the opposite ends of the tracks carried thereby into an overlapped end-to-end relation effective to maintain the driving connection between the first and second interlocking members throughout reversal of the drive element, and said ball and overlapped opposite track ends again cooperating upon continued rotation of said drive element in reverse to overcome the braking action of the braking means yieldably retarding rotation of said inner cam ring while defining a driving connection between the latter and said outer cam ring effective to rotate them as a unit, and said ball tracks and ball further cooperating with one another and with the first biasing means in response to deactivation of said drive means into a free-wheeling condition and rotation of said driven element relative thereto in a direction opposite to that in which said driven element was last driven while said inner cam ring remains restrained against rotation and said tracks are disposed in end-to-end relation to rotate said interlocked first and second interlocking members along with said outer cam ring as a unit to return the paired ball tracks into side-by-side relation thereby retracting said outer cam ring and associated second interlocking member so as to disengage under the influence of the bias exerted thereon by said first biasing means.