Ball transfer unit

Claim 1

In a removable ball transfer unit adapted to receive cargo for movement thereover wherein said unit includes a cylindrical housing having a vertical axis and adapted to be mounted in a platform; a ball race assembly including a cup member, a plurality of roller balls reposing therein and a rotatable cargo engageable ball resting on said roller balls and including a ball cover to prevent removal of said cargo engaging ball from said assembly yet allowing rotation thereof, said assembly being retained within said housing yet adapted to move axially therein within limits, the improvements comprising a load spring having a plurality of convolutions and said spring being seated in said housing and contacting said ball race assembly urging said assembly axially outwardly, said spring convolutions being free of inward restraint and distortable normal to said axis; stop means fixedly mounted in said housing directly engageable by said ball race assembly to limit axial inward movement thereof and releasable locking means associated with said unit adapted to retain said unit in said platform and wherein said stop means includes an axially upwardly projecting frusto-conical member having an opening at the tOp thereof, said opening adapted to receive a portion of said cup member and prevent further axial inward movement thereof.