| 摘要 |
<p>A brake actuator has a force-applying means in the form of a wedge (14) arranged to separate opposed tappets (11, 12) by way of interposed rollers (16, 17). Each tappet is connected by a screw thread to a respective adjuster shaft (39, 40) to form an extendible strut. A drive pinion (21) is engaged by a rack (14C) formed on the wedge and is rotated by actuating movement of the wedge. The pinion drives a sleeve (22) by way of a multi-plate clutch (24), the sleeve in turn driving a secondary pinion (34) via a sprag clutch (33). Another secondary pinion (36) is driven from the first by a drive shaft (35), both secondary pinions being engaged with external teeth (37, 38) respectively on the tappets (11, 12). Both tappets are adjusted simultaneously during brake applying movement of the wedge and the sprag clutch slips during the wedge return movement. The multi-plate clutch (24) slips during excessive actuating loads and renders the adjuster load insensitive.</p> |
