3ff2c1cd_Kosuke___Patent_applications__Description
[Patent application number] 20130239714 [Published] 09-19-2013 [Description] 
BALL SCREW DEVICE, LINEAR ACTUATOR AND VEHICLE STEERING SYSTEM - A ball screw device has a plurality of spiral raceways. One end and the other end of each raceway is connected via a bridge. An annular flange of a ball nut has a plurality of mounting portions at equal intervals in a circumferential direction. A fixing screw is fitted to each mounting portion. The bridges arranged so as to overlap with the annular flange in position in an axial direction are arranged at positions different in the circumferential direction from positions at which the mounting portions are arranged, and are arranged at unequal intervals in the circumferential direction.
Kosuke - Patent applications