| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a wheel cylinder which provides a brake which responses stably in ahead braking and responses at the same level in astern braking as that of the ahead braking, and improves reducing a number of components, in a duo-servo drum brake device. SOLUTION: A control cylinder part 23 which controls hydraulic supply to a driving piston 26 comprises a long diameter piston 37 and a short diameter piston 38 which are held to be slidable at the control cylinder part 23, wherein the short diameter piston 38 is displaced into a control chamber 23a by anchor reactive force in ahead braking, so that the short diameter piston 38 contacts with the long diameter piston 37 and moves together with the long diameter piston 37 from the midway portion, and the short diameter piston 38 presses a secondary shoe 4 to be driven in astern braking.</p> |
