Pressure increase phase (page 2 of 2)

Pressure decrease phase

The electronic control unit measures the locking tendency of the wheel and the ABS device intervenes.

The solenoid valve (4) is activated by a 5 Amp (approx.) current and the connection between the brake pump and the rear right-hand brake caliper is interrupted while the connection between the brake caliper and the recovery pump (5) is opened, being activated at the same time as the solenoid valve (4).

In this way the pressure of the brake fluid in the rear right-hand brake caliper and in the piston chamber (11) connected to it, decreases.

The subtracted brake fluid is once again put into circulation in the main circuit through the recovery pump (5).

This is the origin of the hydraulic pulsations which can be perceived by the driver through the brake pedal.

The accumulator (6), stores the part of the brake fluid subtracted from the brake calipers and at the same time acts as a dashpot chamber for the pressure peaks inherent in the recovery phase.

The inequality between the the forces acting on the piston (11) causes it and the rod (12) to move. The rod, moved by piston (10) moves the piston (11) causing valve (14) to close.

For this reason a progressive reduction in pressure is obtained in the rear left-hand brake caliper provoked by the increase in volume in the piston chamber (10).

The equilibrium of the forces acting on pistons (10) and (11) will be reached when the braking pressure in the rear brake calipers are equal in value.

1. Electronic control unit
2. Brake pump output hose
3. Brake pump output hose
4. Brake pump
5. Solenoid valve for front wheel brake circuit
6. Solenoid valve for front wheel brake circuit
7. Solenoid valve for rear wheel brake circuit
8. Electric recovery pump
9. Accumulators
10. Revolution sensors and phonic wheels for front wheels
11. Revolution sensors and phonic wheels for rear wheels
12. Sequential hydraulic valve
13. Piston
14. Piston
15. Rigid rod connecting pistons
16. Spring
17. Valve