Fiat Bravo Service Manual page 473

Bravo-Brava
Braking system
Anti-lock braking system
33.
Pressure reduction phase
kvxyyxi pressure increase
i i pressure decrease
ECU
+12V
*
B
1
] ^ L ^
1. Electronic control unit 8.
2. Low-pressure accumulator (reservoir) 9.
3. Recycling pump motor 10.
4. Recycling pump 11.
5. High-pressure accumulator (damping 12.
chamber) 13.
6. Brake pump 14.
7. Servo unit
Rapid pressure reducing valve
Inlet solenoid (A) open (B) closed
Outlet solenoid (A) closed (B) open
Brake caliper
Rpm sensor
Phonic wheel
Constriction
The electronic control unit (1) detects the wheel's tendency to lock and activates thS electrohydraulic
unit to limit the wheel deceleration to within the permitted threshold values.
The electronic control unit (1) earths the inlet solenoid (9) and outlet solenoid (10).
The inlet solenoid (9) remains closed, maintaining the break in connection between brake pump (6) and
brake caliper (11); the outlet solenoid (10) opens thus hydraulically connecting the brake caliper (11)
to the low-pressure accumulator (2) and recycling pump (4), in order to remove some of the fluid from
the brake caliper (11) and reduce the pressure on that caliper.
At the same time the electronic control unit (1) supplies the motor (3) for driving the recycling pump (4)
which returns fluid removed from the brake caliper (11) into the main circuit. The accumulator (2) or
low pressure reservoir present in the circuit stores some of the brake fluid removed from the calipers.
Through the circuit of the recycling pump (4), the brake fluid is drawn in and sent, through the damping
chamber (5) and constriction (14), into the main circuit of the brake pump (6). During this phase, a se­
ries of pressure waves (or hydraulic thrusts) is generated, and these are attenuated by the presence of
the damping chamber (5) and constriction (14). During this phase, because of the reduction in the
braking force, the wheel tends to assume the reference speed calculated by the electronic control unit
(1)-
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