Adjustable roller assembly

Claim 1

A ROLLER ASSEMBLY FOR A CLOSURE MEMBER HAVING A LOWER EDGE MOVABLE ALONG A SUPPORTING TRACK, SAID ASSEMBLY COMPRISING A FRAME MOUNTABLE ON SAID MEMBER ADJACENT SAID EDGE, A CARRIER GUIDED ON SAID FRAME FOR BACK AND FORTH MOVEMENT TOWARD AND AWAY FROM SAID TRACK, A PAIR OF SPACED ROLLERS JOURNALED ON SAID CARRIER WITH PERIPHERAL PORTIONS THEREOF ADJACENT SAID EDGE FOR ROLLING ENGAGEMENT WITH SAID TRACK, AN INWARDLY FACING FOLLOWER ON SAID CARRIER BETWEEN SAID ROLLERS, A CAM JOURNALES ON SAID FRAME ABOVE SAID FOLLOWER FOR ROTATION ABOUT AN AXIS GENERALLY PERPENDICULAR TO THE PLANE OF SAID MEMBER AND HAVING A STEPPED PERIPHERAL SURFACE ENGAGEABLE WITH SAID FOLLOWER TO HOLD THE CARRIER AGAINST UPWARD MOTION, SUCCESSIVE STEPS ON SAID SURFACES BEING SPACED PROGRESSIVELY INCREASING DISTANCES FROM SAID AXIS TO LOWER SAID CARRIER AND SAID ROLLERS RELATIVE TO SAID FRAME AS SAID CAM TURNS IN ONE DIRECTION TO BRING SUCCESSIVE STEPS INTO ENGAGEMENT WITH THE FOLLOWER, AND MEANS FOR ROTATING SAID CAM RELATIVE TO SAID FOLLOWER TO VARY THE POSITIONS OF SAID ROLLERS.