| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an operating valve mechanism which can avoid the sudden opening and closing of a liquid passage, can prevent the sudden change of a supply amount of hydraulic fluid in the case that it is employed, for example, for the steering wheel cylinder of a duo-servo drum braking device, and can realize impact damping at sudden braking time and fine control of braking force. SOLUTION: When a supply amount of hydraulic fluid is suddenly increased, hydraulic fluid supply is changed over to a narrow clearance 162 between a valve assembly 111 and a valve guide 110 by the displacement of the valve assembly 111 so as to suppress the sudden increase of the supply amount, and when a liquid passage 112a is closed by the displacement of a control piston 112, the liquid passage 112a is gradually narrowed by a conical surface part 110a equipped on the shaft part 110b of the valve guide 110 so as to prevent the sudden closing of the liquid passage 112a.</p> |
