US Patent 7124861 Motion control apparatus

A brake (10) having application for a linear or rotational motion device includes a housing (120) in which a first piston (140), a wedge (142) and a second piston (144) cooperate to engage a friction facing (136) through a plurality of rollers (152, 154, 156, 158). The three part piston assembly (148) allows a braking action and prevents torsional forces that are non-axial to the axis of the first piston (140) and second piston (144). The pistons (140, 144) are biased by compression springs (176) and may be actuated by a fluid.