Electrically controlled brake systems for railway cars employing spring-applied power-released unit brake assemblies

Claim 1

A UNIT BRAKE ASSEMBLY FOR A VEHICLE WHEEL COMPRISING: (A) BRAKE SHOE MEANS FOR APPLYING A BRAKING FORCE TO A VEHICLE WHEEL, (B) A PIVOTED LEVER EFFECTIVE UPON ROCKING IN ONE DIRECTION TO APPLY SAID BRAKE SHOE MEANS AND UPON ROCKING IN THE OPPOSITE DIRECTION TO RELEASE SAID BRAKE SHOE MEANS, AND (C) MEANS FOR ACTUATING SAID PIVOTED LEVER INCLUDING: (I) A SCREW-THREADED MEMBER ROTATABLY MOUNTED FOR ROTATION ON ITS LONGITUDINAL AXIS, (II) SPRING MEANS CONNECTED TO SAID SCREW-THREADED MEMBER SO AS TO BE WOUND UP UPON ROTATION OF THE SCREW-THREADED MEMBER IN ONE DIRECTION AND TO EXERT A FORCE TENDING TO ROTATE SAID SCREWTHREADED MEMBER IN THE OPPOSITE DIRECTION, (III) A TRAVELING NUT OPERATIVELY ASSOCIATED WITH SAID SCREW-THREADED MEMBER AND CONNECTED TO SAID PIVOTED LEVER SO AS TO ROCK SAID LEVER IN OPPOSITE DIRECTIONS CORRESPONDING TO THE DIRECTION OF TRAVEL OF SAID TRAVELING NUT ON SAID SCREWTHREADED MEMBER, AND (IV) POWER MEANS FOR ROTATING SAID SCREW-THREADED MEMBER IN ONE DIRECTION TO CAUSE TRAVEL OF SAID TRAVELING NUT IN A DIRECTION TO ROCK SAID PIVOTED LEVER TO RELEASE SAID BRAKE SHOE MEANS AND TO MAINTAIN IT THERE AND AT THE SAME TIME TO CAUSE WIND-UP OF SAID SPRING MEANS.