Ball Transfer Units
Ball transfer units are omnidirectional load-bearing spherical balls mounted inside a restraining fixture. They are identical in principle to a computer mouse / trackball (pointing device). Typically the design involves a single large ball supported by smaller ball bearings.
Commonly used in the inverted ball up position, objects are quickly moved across an array of units, this is known as a ball transfer table, a type of conveyor system. This permits manual transfer to and from machines and between different sections of another conveyor system. They are used in airports for luggage delivery, or in industry as part of manufacturing systems.
Ball transfer units can also be used in a non-inverted ball down position as a type of caster, however this use is restricted by load-bearing limitations and the type of floor.
Manufacturers have addressed this problem with ball transfer units incorporating re-circulating ball principles, however the inverted position is still the most common application and the least problematic.