| 摘要 |
PROBLEM TO BE SOLVED: To obtain a motor having sufficient axial rigidity in which durability and vibration resistance are enhanced by making an inner circumferential rolling groove of a plural row bearing directly in the outer circumference at the large diameter shaft part of a two stage shaft having large and small diameter shaft parts. SOLUTION: A two stage shaft 1 has large and small diameter shaft parts 1a, 1b and an inner circumferential rolling groove 2a is made in the outer circumference of the large diameter shaft part 1a. Balls 4 for one side row are arranged between an outer circumferential rolling groove 2b made in the inner circumferential surface of an outer ring 3 surrounding the large diameter shaft part 1a and the inner circumferential rolling groove 2a made in the large diameter shaft part 1a before being assembled in the large diameter shaft part 1a. The small diameter shaft part 1b of the two stage shaft 1 is fitted removably with the inner ring 6 of a ball bearing 5 comprising inner and outer rings 6, 7 and arranged with another row of balls 9 between respective rolling grooves 8a, 8b of the inner and outer rings. When the inner circumferential rolling groove 2a is made directly in the outer circumference at the large diameter shaft part 1a of the two stage shaft 1, a two stage shaft having a corresponding large diameter part is obtained and the diameter of the outer ring 3 can be reduced without sacrifice of rigidity of the shaft. |
