a reciprocating drive for operative axial communication with a brake disk stack through a pressure plate to compress the disk stack for braking of a rotatable wheel comprises : a relatively stationary annular housing ; an annular ram member mounted coaxially within the housing and adapted for axial movement and contacting engagement with the pressure plate to effect compression of the brake disk stack ; a relatively rotatable annular ring gear member mounted coaxially between the housing and the ram member ; a plurality of rollers operative between the rotatable ring gear and ram members to effect an axial movement of the ram member when interacting with the rotatable ring gear member ; and at least two high torque motors mounted within the housing and having pinion drives for operative engagement with the ring gear member to rotate the member in response to an electrical signal . the rollers may comprise a planetary drive or a recirculating roller drive with suitably configured ring gear and ram member engagement surfaces .