Patent ID: 7077259

Claim:
A drive assembly for longitudinally moving a pair of carrier elements along a hub having a longitudinal axis and rotating about the longitudinal axis, the drive assembly comprising: a frame; a rail disposed longitudinally along the hub and spaced from the longitudinal axis, the rail configured to carry the carrier elements; a ring fixedly mounted to the frame and disposed about the hub, the ring defining a track and including a stationary portion and a rotating portion, the rotating portion being operably connected to a drive; first and second rotating shafts disposed on the hub, longitudinally spaced from and aligned with one another, the first shaft being a driven shaft and including a head portion disposed at and guided by the ring, the second shaft being an idler shaft; a continuous, flexible element disposed about the first and second shafts for rotational movement about the shafts, the flexible element, disposed about the shafts, defining opposing elongate sides and return portions at the shafts, the carrier elements being mounted to the flexible element; and the drive mounted to the frame and operably connected to the ring rotating portion for rotating the ring rotating portion, wherein the head portion, traverses along the ring track into the rotating ring portion and is engaged and rotated by the rotating ring portion and wherein rotation of the head portion rotates the flexible element to move the carrier elements along the rail.