Model RS rolling ring linear drive nuts with an RS8 drive run on an 8mm-diameter case-hardened and ground, smooth shaft and supports space-saving machine design trends toward smaller components. Currently being used in small-axis optical metrology machines, the RS8 nut is the smallest drive in the RS line, yet it provides the same axial thrust (100 Newtons) as the next larger size drive unit. The new RS8 features zero backlash linear motion. The inner race of each rolling ring bearing is in constant point-contact with the shaft. There is no play or free movement between shaft and bearings — even during reversal. This assures that when the shaft rotates the rotary motion input is immediately converted into linear output.