Barn sweeper

Claim 1

IN A DEVICE OF THE CLASS DESCRIBED, (A) A GENERALLY HORIZONTALLY DISPOSED SUPPORTING FRAME, (B) WHEEL MEANS SUPPORTING SAID FRAME IN SPACED RELATION TO A SURFACE TO BE SWEPT, (C) A ROTOR JOURNALLED IN SAID FRAME ON A VERTICAL AXIS CENTRALLY THEREOF, (D) SAID ROTOR INCLUDING A PLURALITY OF CIRCUMFERENTIALLY SPACED RADIALLY OUTWARDLY PROJECTING ARMS, (E) BRUSH ELEMENTS CARRIED BY THE OUTER END PORTIONS OF SAID ARMS, (F) MEANS MOUNTING THE RADIALLY INNER ENDS OF SAID ARMS FOR PIVOTAL RAISING AND LOWERING MOVEMENTS OF THE BRUSH-EQUIPPED OUTER ENDS THEREOF, (G) MEANS YIELDING BIASING SAID ARMS IN A DOWNWARD DIRECTION, (H) A CAM RING CONCENTRIC WITH SAID ROTOR, (I) SAID CAM RING HAVING A RELATIVELY ELEVATED PORTION WHICH EXTENDS FOR AT LEAST 180* OF CIRCULAR ARC AND A RELATIVELY DEPRESSED PORTION WHICH EXTENDS FOR LESS THAN 180* OF CIRCULAR ARC, (J) AND CAM FOLLOWER MEANS CARRIED BY SAID ARMS, (K) SAID CAM FOLLOWER MEANS RAISING SAID ARMS AND THE BRUSHES CARRIED THEREBY ABOVE THE LEVEL OF THE SWEEPING SURFACE DURING ENGAGEMENT WITH THE RELATIVELY ELEVATED PORTION OF SAID CAM RING AND PERMITTING SWEEPING ENGAGEMENT OF SAID BRUSH ELEMENTS WITH SAID SURFACE WHEN OVERLYING SAID RELATIVELY DEPRESSED PORTION OF SAID CAM RING.