Modes of Operation

Front Base Braking Mode:

BASE BRAKE MODE
The brake systems operates using conventional braking by means of brake pedal force, the vacuum booster, and the compact master cylinder. Each front channel consists of a motor, solenoid, ESB, ball screw, piston, and check valve. Under normal operating conditions (base brakes), the piston is held in the upmost (or home) position and the solenoid is open (not energized). This is accomplished by turning the ball screw via the motor to drive the nut upwards. Once at the upmost position, the piston is held by an Expansion Spring Brake (ESB).

ANTI-LOCK MODE
Two paths are available to transfer braking pressure to the wheel. Through the modulator, around the check valve, and out to the wheel or through the modulator, past the normally open solenoid, and out to the wheel. The solenoid in the front circuits provides an alternate brake pressure path to the wheel.

FAIL-SAFE MODE
If the ABS were to lose power or malfunction with the piston not in its home position, a redundant brake fluid path is available. The rear channels operate in a similar manner except no solenoid exists.