Abstract: A dirt ejecting ball transfer unit comprises a housing containing a cup with a substantial aperture, and a load bearing ball supported on ball bearings. The housing is provided with a series of apertures that overlap with the cup's substantial aperture to define a plurality of passage entries into the housing apertures. The passage entries have an elongate shape. The housing apertures have a minimum width which is substantially larger than the minimum width of the passage entries. Dirt and other contaminants that penetrate the seals of the ball transfer unit are quickly ejected through the housing apertures when the ball is rotated under load, thereby preventing failure of the ball transfer unit.

Abstract: A ball deck is disclosed capable of conveying a container having an uneven bottom surface. The ball deck, having an upper surface, houses a plurality of ball transfer units. Each ball transfer unit has a first housing having an upper end terminating adjacent the upper surface of the ball deck. A first load supporting ball, which is preferably hollow, is disposed in an upper section of the housing and has a portion extending above the upper surface of the ball deck. A second load supporting ball, having a lesser diameter than the first ball, supports the first ball. A spring biases the balls axially upward by allowing the first ball to move between an upward position and a downward position when supporting an irregular load surface.