S60 L5-2.4L VIN 64 B5244S6 (2003)
Brake Proportioning/Combination Valve: Description and Operation
Electronic brake force distribution (EBD)
Electronic Brake Force Distribution (EBD) is integrated in the ABS system and controls the braking forces to the rear wheel brakes. Electronic brake
force distribution (EBD) replaces the relief valve, which otherwise reduces the pressure in the brake circuit for the rear wheels and prevents premature
activation of rear ABS control. Electronic brake force distribution controls the hydraulic pressure in the brake circuit for the rear wheels the rear
wheels slip considerably less than the front wheels under braking. This ensures optimal and stable braking. The Brake Control Module (BCM)
controls the brake pressure by controlling the inlet and outlet valves in the rear wheel brake circuits.
The brake pressure in the rear wheel circuits varies, depending on how much the rear wheels slip in relation to the front wheels. This functions tries to
keep the rear wheel slippage 0-2 % lower than front wheel slippage. The function is load sensitive.
Generally, the difference between the rear wheel and front wheel slippage under braking is dependent on how hard the brakes are applied and on the
load of the car. Hard braking /light loads cause more slippage, light braking/heavy loads cause less slippage. Therefore the requirement for brake fluid
when the hydraulic pump is not activated during electronic brake force distribution (EBD) control is less than during stability and traction control. The
fluid volume returned from the brake circuits is taken up by the accumulators.
