| 摘要 |
<p>PURPOSE: To prevent air from penetrating into a housing by maintaining the extent of lubricating pressure in a cavity to the specified positive pressure according to a variation in the effective volume of this cavity in time of braking operations. CONSTITUTION: A lubricant is injected into a clearance between a camshaft 35 and a tubular member 36, and then it comes into a housing 54 by way of a groove in a bushing 62, thereby lubricating an operating mechanism 31 stored in this housing 54. A chamber is formed in an actuator 31 by a cover plate 139 and the housing 54, and a contractile element 143 such as a foaming body or the like consisting of a closed cell is stored in this air space. This element 143 is compressed by what the lubricant is introduced. In the case where volume in the housing 54 grows larger by braking operations, the foaming body 143 is expanded whereby pressure in the lubricant is maintained in the specified value.</p> |
