 Many modern precision drives provide the eccentric motion through multiple shafts that also transmit the output force, typically 2 to 5 shafts arranged in the same circular pattern as the output rollers of the most basic design, the shafts are driven through planetary-like gears by a central input shaft.Since these shafts are always aligned by the input gears this allows the output to be transmitted through roller bearings rather than intermittent surface contact.Due to the planetary input this is effectively a two-stage drive and may be designed to be directly driven by a high speed brushless motor, this type is often used in robot actuators.