| 摘要 |
PROBLEM TO BE SOLVED: To improve dynamic follow-up performance at braking time, and smoothly actuate a brake by constituting a member slidingly contacting with a thrust shaft of a rotation stopping means out of a member having small sliding resistance to a rectilinear directional movement of the thrust shaft. SOLUTION: When an outer cylinder 40 moves in the shaft direction by assist thrust from an electric motor 26, a shaft directional movement is guided by a large number of balls 45, and rotation of the outer cylinder 40 is regulated by the respective balls 45. A detent means for regulating following rotation of the outer cylinder 40 by rotation of this electric motor 26 is composed of a cutout part 42a formed on a regulating plate 42, the balls 45 and a sliding groove 40c formed in the outer cylinder 40. Since the co-rotation of the outer cylinder 40 is received and regulated by the balls 45, sliding resistance to the shaft directional movement of the outer cylinder 40 is extremely reduced by the sliding resistance reducing action by rotation of the balls 45 to thereby improve dynamic follow-up performance at braking time to smoothly actuate a brake according to an intention. |
