Transfer Ring Having Advantaged Cam Follower-Camming Groove Aspect and Method

A transfer ring comprising:

• at least one circular frame member defining a substantially planar side surface;
• a circular drive member defining a central axis, said drive member being rotatably mounted about said central axis in parallel-planar relationship along said side surface;
• a plurality of cam followers extending from said drive member perpendicular to said side surface;
• a plurality of hinge pin connectors extending from said side surface;
• a plurality of elongated driven links having opposite first and second ends thereof, each said driven link first end being rotatably mounted to one of said respective hinge pin connectors such that said each said driven link is rotatable between a contracted position with said driven link second ends extending toward said central axis and a retracted position with said driven link second ends extending along said circular frame member, each said driven link defining a curved, elongated camming groove extending along at least a portion of said driven link, each said cam follower being received within one of said camming grooves;
• and
• a plurality of shoes having inner surfaces facing substantially radially inwardly toward said central axis to collectively define a substantially circular gripping surface, each said shoe being rotatably mounted on one of said driven link second ends;
• whereby rotation of said drive member about said central axis moves said cam followers about said central axis and along said respective camming grooves, thereby rotating each said driven link about said respective hinge pin connector to alter a diameter of said gripping surface between said contracted position and said retracted position.