A brake system for actuating a plurality of wheel brakes comprising first and second pairs of wheel brakes, the system comprising:
- a reservoir;
- a motor-driven master cylinder operable during a normal non-failure braking mode by actuation of an electric motor of the master cylinder to generate brake actuating pressure at first and second MC outputs for hydraulically actuating the first and second pairs of wheel brakes, respectively;
- a secondary brake module configured for selectively providing pressurized hydraulic fluid at first and second pump outputs for actuating the first and second pairs of wheel brakes in at least one of a normal non-failure braking mode and a backup braking mode, the secondary brake module including an electric PTU motor configured to selectively pressurize the hydraulic fluid by transmitting rotary motion to at least two pump pistons, each pump piston providing pressurized hydraulic fluid to a corresponding one of the first and second pump outputs, each of the first and second pump outputs providing fluid to a corresponding one of the first and second pairs of wheel brakes;
- a first traction control iso valve hydraulically interposed between the motor-driven master cylinder and the first pair of wheel brakes via the first MC output;
- a second traction control iso valve hydraulically interposed between the motor-driven master cylinder and the second pair of wheel brakes via the second MC output;
- a first bypass type valve hydraulically interposed between the first MC output and the first pair of wheel brakes, the first bypass type valve being hydraulically connected to a front brake of the first pair of wheel brakes by a first front brake line, and the first bypass type valve being hydraulically connected to a rear brake of the first pair of wheel brakes by a first rear brake line;
- a first front check valve restricting fluid flow within the first front brake line from the front brake of the first pair of wheel brakes toward the first bypass type valve;
- a first rear check valve restricting fluid flow within the first rear brake line from the rear brake of the first pair of wheel brakes toward the first bypass type valve;
- a second bypass type valve hydraulically interposed between the second MC output and the second pair of wheel brakes, the second bypass type valve being hydraulically connected to a front brake of the second pair of wheel brakes by a second front brake line, and the second bypass type valve being hydraulically connected to a rear brake of the second pair of wheel brakes by a second rear brake line;
- a second front check valve restricting fluid flow within the second front brake line from the front brake of the second pair of wheel brakes toward the second bypass type valve;
- a second rear check valve restricting fluid flow within the second rear brake line from the rear brake of the second pair of wheel brakes toward the second bypass type valve;
- and
- an electronic control unit for controlling at least one of the secondary brake module and the master cylinder responsive to at least one brake pressure signal.