| 摘要 |
<p>A helical thrust bearing (14) is arranged between two rotatable cam components (12 and 13) of a brake actuator. The cam component (13) is turned first while the brake slack is being taken up and the brake-applying force is relatively low, the reaction to such force being transmitted to the body (10) at a plain axial thrust bearing (17,18). Only the cam component (12) is turned when the brake is actually being applied with the relatively high brake force which is transmitted to a thrust member (15) at a roller axial thrust bearing (16). This enables the pneumatic force motor or the prime mover to be used more efficiently. Also a greater angular displacement at the helical thrust bearing (14) is obtained for a given angular displacement of the cam components (12 and 13) relative to the body (10). In a modification, the plain thrust bearing (17,18) is replaced by another helical thrust bearing.</p> |
