Most screw-based motion systems use a rotating screw and a nonrotating nut to controls speed and position.
But screws can limit speed and travel distance. A ball nut from Rexroth Bosch Group, Charlotte, N.C. (boschrexroth-us.com), the FAR Rotating Nut, overcomes these limits to deliver speeds to 150 m/min and lengths to 6 m. The design eliminates end bearings, which shorten the service life of standard ball screws. The lack of end bearings also lets the screw be preloaded to higher levels, making it mechanically stiff and better able to compensate for changing temperatures. A central lubrication port simplifies maintenance. The nut is manufactured with four different diameter ranges with varying leads and can be delivered as a preassembled system with toothed belt, timing belt, and ac servomotor.