| 摘要 |
<p>PURPOSE:To provide a master cylinder of a brake apparatus for vehicles, wherein when a brake shoe has been worn out and the stroke of the master cylinder has exceeded a prescribed value, a hydraulic liquid is immediately replenished through a hydraulic pump thereby excess movement of the stroke is prevented, its adjusting apparatus can be omitted, and the structure thereof is simplified. CONSTITUTION:Bores 9, 10 are formed in the piston 3, and a check valve 13 and a residual pressure valve 14 are fitted in the bore 9. The valve 13 is pushed rearward by a spring 15, and the valve 14 is pushed forward by a spring 16. When the piston is restored, a stopper 20 of a cylinder body 1 separate the valve 13 from a valve sheet 17. The relationship of a distance A between a communication port 1a to a reservoir and a communication port 1b to a hydraulic pump, the distance C between the stopper 20 and the residual pressure valve 14, and a width B of a groove 25 of the piston 3 is constructed such that when the piston 3 proceeds for the distance C, the stopper 20 and the residual pressure valve 14 abut to each other, and when the groove 25 is located at the distance A, the bore 26 is cut off the ports 1a, 1b, and the piston 3 is further moved, while the valve 14 is opened, and the groove 25 becomes in communication with the port 1b. When the stroke has become excessive due to the wear, the valve 14 is opened, and the hydraulic liquid is replenished through the pump.</p> |
