Patent ID: 8838355

Claim:
A braking device comprising: a tandem type master cylinder including a plurality of hydraulic chambers which generate hydraulic fluid pressures by an operation of a brake pedal by an operator; an operation quantity detecting unit for detecting an operation quantity of the brake pedal; a plurality of systems of hydraulic passages connecting the hydraulic chambers of the master cylinder to a plurality of wheel cylinders; a hydraulic pressure source installed in the systems of hydraulic passages and being capable of pressurizing a hydraulic fluid in the hydraulic passages based on the operation quantity detected by the operation quantity detecting unit; cutoff valves installed in the systems of hydraulic passages, respectively, between the master cylinder and the hydraulic pressure source, and being closed in a closing command state or being opened in an opening command state; a plurality of hydraulic pressure detecting units for respectively detecting hydraulic fluid pressures of the hydraulic passages on a side of the wheel cylinders with respect to the cutoff valves; and a brake control unit, wherein: when the cutoff valves are in the opening command state the brake control unit performs a first mutual diagnosis based on the hydraulic pressures detected by the hydraulic pressure detecting units, an operation quantity detected by the operation quantity detecting unit, and a previously stored characteristic between the operation quantity and the hydraulic pressure detected by at least one of the hydraulic pressure detecting units which are continuously variable, and performs a second mutual diagnosis based on the hydraulic pressures detected by the hydraulic pressure detecting units, when the cutoff valves are in the closing command state the brake control unit performs the first and second mutual diagnoses, and the brake control unit detects failure in the cutoff valves and the hydraulic pressure detecting units based on of results of the first and second mutual diagnoses in the closing command state and the opening command state of the cutoff valves.