Anti-Lock Braking System (ABS)

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Volvo S80, 2005 Volvo S80, 2004 Volvo S80, 2003 Volvo S80, and 2002 Volvo S80. However, it is still accessible from the selected car via links, so may be relevant.

Is activated by the likelihood of the wheels locking during braking and ensures that the maximum braking effect is retained without the wheels locking. This is to retain the cars driveability and steering capacity.

The function comes into operation at speeds in excess of 7 km/h (4 mph). At lower speeds the wheels can lock, but this has no practical effect on the brake or steering capacity.

The ABS system is a four channel system. This means that each wheel is controlled individually.

There is an inlet valve (C1, C2, C3 and C4) and outlet valve (D1, D2, D3 and D4) for each channel in the ABS hydraulic modulator. Furthermore there are two receivers (A1 and A2), one for the primary (LF+RR) and one for the secondary (RF+LR) circuits.

In start position all the valves are in the resting position, that is to say that the inlet valves are open and the outlet valves are shut and the receivers have no pressure.

There is a return valves for each inlet valve. The valve is opened by the high brake pressure at the wheel when the pedal is released. This makes the brakes release quickly and avoids "delayed release".