| 摘要 |
This invention relates to a spring-applied power-released brake assembly for each individual wheel of a railway car truck, wherein the brake assembly comprises an electrical torque motor that is effective when fully energized to cause a brake release by moving the fulcrum for a proportioning or variable ratio lever relative to this lever against the yielding resistance of a comparatively light control spring to a position in which a comparatively heavy brake-applying spring becomes effective to bias this lever in the brake-release direction. As the current supplied to the torque motor is reduced, the control spring is rendered effective to shift the fulcrum relative to the lever to a position in which the brake-applying spring is effective via one arm of the variable ratio lever to bias this lever in a brake-applying direction and thereafter, in response to a further reduction of current, to increase the length of this one arm to thereby render the brake-applying spring effective via this lever to correspondingly increase the braking force on the wheel.
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