To reduce the number of components, and to change the particulars and the target values of a reduction gear only by changing a worm shaft by omitting a motor side bearing out of a pair of bearings to support the worm shaft, and supporting the worm shaft by a drive shaft of an electric motor and one bearing.
A worm shaft 6 is separate from a drive shaft 4 of an electric motor 3, and a cylindrical female spline shaft 5 with a female spline in an inner circumferential surface is fixed to the drive shaft 4 of the motor 3. A male spline part 7 of a motor side end part of the worm shaft 6 is spline-fitted to the female spline shaft 5 movably in the axial direction. The worm shaft 6 is rotatably supported by a bearing 21 only at the counter-motor end part.
IGARASHI MASAHARU
TSUNODA TOMOYUKI
NSK STEERING SYS CO LTD