Ball transfer units consist of a large ball seated on a quantity of small ball bearings in a hemispherical cup. There are from 80 to 150 ball bearings in the cup depending on what size the unit is. This design enables the large ball to rotate freely and instantaneously in any direction. Extremely heavy loads can be moved with the minimum of effort.
The units are pre-lubricated during manufacture and, aside from a cleaning them every now and then, they are effectively maintenance free.
Ball transfer units are generally mounted into a conveying table top and used to enable items such as metal and wood sheets to be moved around a factory.