TANDEM POWER TRANSMISSION UNIT AND BRAKE SYSTEMS USING SAME

A tandem power transmission unit includes a ball screw and a ball nut selectively driven by the ball screw for longitudinal motion relative thereto. A primary piston is operatively coupled to the ball nut. A secondary piston is operatively coupled to the primary piston. A primary chamber is configured to contain hydraulic fluid and is selectively pressurized by reciprocal motion of the primary piston. A secondary chamber is configured to contain hydraulic fluid and is selectively pressurized by reciprocal motion of the secondary piston driven indirectly by longitudinal motion of the ball nut. A first output channel selectively places the primary chamber in fluid communication with at least one component of a brake system for provision of pressurized hydraulic fluid thereto. A second output channel selectively places the secondary chamber in fluid communication with at least one component of a brake system for provision of pressurized hydraulic fluid thereto.