Electric actuator for brake of railway vehicle - determines output force produced by spring system and stop position of which is adjusted according to variation of required maximum force

摘要

The actuator includes a power spring (1) extending between a wall (2) of the actuator housing (3) and a flange (4) on the output member (5). A control spring (10) is compressed between a second flange (7) projecting from a cylindrical member (6) which extends from the first flange (4). The control spring is compressed sufficiently to balance totally the force exerted by the power spring on the output member. The motor is operated to rotate a pinion (13). This acts through a gear (12) and ball-screw sleeve (11) to move a nut (9) on the sleeve in a given direction to allow the control spring to extend so as to reduce the force which it applies to the power spring. Consequently, there is no longer a balance of forces and the imbalance force is applied to the output member to actuate braking equipment. A second motor (26) oprates in accordance with the loading of the railway vehicle on which the braking equipment is mounted. The position of the flange (21), which forms the adjustable stop for limiting movement of the nut (9), is varied.