Two stacks of toroidal magnets (33, 34, 35 and 37, 38, 39) are coaxially mounted and polarized so that the first stack (33, 34, 35) is centered and spacially supported within the second stack (37, 38, 39). The second stack is mounted in a stationary base (26) while the first stack is mounted in a support...http://www.google.es/patents/US4471331?utm_source=gb-gplus-sharePatente US4471331 - Magnetically supported work fixture
