| 摘要 |
<p>A wheel cylinder (5) for expanding the opposed edges at one longitudinal end of a pair of brake shoes (1,10) includes a pair of drive pistons (502,520) for pressing the ends of the respective brake shoes (1,10) under a hydraulic pressure supplied to the first pressure chamber (110), and a pair of control pistons (51,55) which receive at the base ends the hydraulic pressure from the master cylinder and receive at the front ends anchor reaction force by way of levers (3,30), the control pistons (51,55) being displaced to close a normally-open input control valve (54) for supplying hydraulic pressure to the first pressure chamber (110) when the anchor reaction force becomes larger than the hydraulic pressure received from the master cylinder by a predetermined magnifying power. Accordingly, it is possible to increase the stability of the braking effect of a duo-servo type drum brake.</p> |
