ABS modulation: Notes

Fig 1: Identifying ABS Modulation Graph

Courtesy of SAAB-SCANIA OF AMERICA, INC.

1. Speed
2. Braking force
3. Road speed
4. Wheel speed (of rotation)
5. Inlet valve open, outlet valve closed
6. Inlet valve closed, outlet valve closed
7. Outlet valve open, return pump actuated

When the control module detects that the retardation of a wheel is too high (increase in wheel speed), it modulates the brake pressure in three phases.