| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the occurrence of drag to a brake during disengagement of brake operation even when a motor fails in operation during operation of a brake, in a motor-driven brake driven by a motor serving as a drive source. SOLUTION: A motor-driven brake 10 causes a motor 40 to be linked to an inner pad 20a through a planetary roller screw 80, a ball screw 96, and a pressure shaft 64 and a ball screw 96 is provided with a selector 110 to selectively allow relative rotation between a nut 98 and a pressure shaft. Normally, the relative rotation is blocked by the selector and the function of a ball screw is rendered ineffective. Meanwhile, when, during release of brake operation, the pressure shaft is not moved in a direction in which the shaft is separated from the inner pad, relative rotation is allowed by the selector and the function of the ball screw is rendered effective. This constitution allows the inner pad to move in a direction, in which the inner pad is separated away from the disc 12, without rotation of the motor.</p> |
