Pressure increase phase

Pressure increase phase

1. Electronic control unit
2. Low pressure accumulator (reservoir)
3. Recovery pump drive motor
4. Recovery pump
5. High pressure accumulator (damping chamber)
6. Brake control pump
7. Servobrake
8. Fast pressure reduction valve
9. Charge solenoid valve
10. Discharge solenoid valve
11. Brake caliper
12. Revolution sensor.
13. Phonic wheel
14. Restrictor

When the driver presses the brake pedal, the pressure generated by the brake pump (6) reaches the brake caliper without undergoing changes, as the solenoid valves (9) and (10) of the hydraulic unit are not connected to earth by the electronic control unit. When the braking force increases, deceleration of the wheel increases accordingly; this causes faster deceleration of the car (i.e. wheel slip increases).

The slip rate must not exceed a determine value beyond which the wheel loses its grip on the ground and starts to slide, losing direction and lengthening braking distances.

The revolution sensor (12) signals that deceleration values have been reached that would compromise the grip of the wheel with the ground: at this point the electronic control unit (1) commands the solenoid valves of the electrohydraulic unit, reducing the braking force and allowing the wheel to increase speed and recover grip.