US 5,868,226 AGranted

Screw-released roller brake

AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration

InventorJohn M. Vranish

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Abstract

A screw-released roller brake including an input drive assembly, an output drive assembly, a plurality of locking sprags, a mechanical tripper nut for unlocking the sprags, and a casing therefor. The sprags consist of three dimensional (3-D) sprag members having pairs of contact surface regions which engage respective pairs of contact surface regions included in angular grooves or slots formed in the casing and the output drive assembly. The sprags operate to lock the output drive assembly to the casing to prevent rotation thereof in an idle mode of operation. In a drive mode of operation, the tripper is either self actuated or motor driven and is translated linearly up and down against a spline and at the limit of its travel rotates the sprags which unlock while coupling the input drive assembly to the output drive assembly so as to impart a turning motion thereto in either a clockwise or counterclockwise direction.

Claims21

Dependent claims

A roller brake assembly, comprising:

rotatable input drive means including a driven screw member located along a central rotational axis;
rotatable output drive means coaxially located along said central rotational axis adjacent said screw member and including an inner portion having at least one spline surface region and an outwardly facing sprag contact surface region;
outer casing means having an interior inwardly facing sprag contact surface region opposite said outwardly facing sprag contact surface region of said output drive means;
sprag means located between said inner portion of said output drive means and said casing and being in contact with said outwardly and inwardly facing sprag contact surface regions and being spring biased so as to lock said output drive means to said casing in absence of said input drive means being rotated;
and
tripper nut means located on said screw member and being restrained from rotation by said spline surface region while being translated up or down said screw member between stops at opposite ends of said screw member when said screw member is driven in a clockwise or counterclockwise direction, said tripper nut means further including means for unlocking said sprag means from said casing upon translating to said stops and locking said input drive means to said output drive means when said input means is rotated.

3 more elements

Dependencies are inferred from the claim text.