Brake system, anti-lock brake system with automatic brake differential ABD/ETS, function

The following operation diagram shows the course of the pressure in the brake system of the “front left” brake circuit with the electromagnetic valves in “Create pressure” position, in the case of ABD or ETS braking.

The changeover valve (USV1) is activated and in “Maintain pressure” position and the electromagnetic valve (ASV1) activated and in “Pressure pass” position.

The course of the pressure

- The brake liquid pumped by the pump (RFP1) through the magnetic valve (ASVA), the damping chamber (D1) and the

magneticvalve (EVVL), reaches the wheel brake cylinder. The braking pressure is established and the front left wheel is braked.

- The brake liquid cannot return through the electromagnetic valve (USV1) as it is activated and in “Maintain pressure” position.

S42.30-0044-12

Example: Electromagnetic valve (ASV1) activated, “Pressure pass” position and changeover valve (USV1) in “Maintain pressure” position

Brake circuit distribution: Diagonal

A2 Hydraulic unit

ASV ABD or ETS intake valve

D Damping chamber

AVHR ABS electromagnetic valve, reduce pressure, rear right

AVVR ABS electromagnetic valve, reduce pressure, front right

AVHL ABS electromagnetic valve, reduce pressure, rear left

AVVL ABS electromagnetic valve, reduce pressure, front left

EVHR ABS electromagnetic valve, maintain pressure, rear right

EVVR ABS electromagnetic valve, maintain pressure, front right

EVHL ABS electromagnetic valve, maintain pressure, rear left

EVVL ABS electromagnetic valve, maintain pressure, front left

SPK Accumulator chamber

RFP Feedback pump

RVR Retaining valve

USV ABS or ETS changeover valve

HZ1 Brake circuit 1 of main cylinder

HZ2 Brake circuit 2 of main cylinder

The following operation diagram shows the course of the pressure in the brake system of the “front left” brake circuit, with “Maintain pressure” position in the case of ABD or ETS braking.

The changeover valve (USV1) is activated and in “Maintain pressure” position and the electromagnetic valve (ASV1) in standby position.

The course of the pressure

- The brake liquid cannot be sucked by the feedback pump (RFP1) through the magnetic valve (ASV1).

- The pressure is maintained constant in the electromagnetic valve (USV1) and the wheel cylinder.

S42.30-0045-12

Example: Electromagnetic valve (ASV1) in standby position and changeover valve (USV1) activated and in “Maintain pressure” position

Brake circuit distribution: Diagonal

A2 Hydraulic unit

ASV ABD or ETS intake valve

D Damping chamber

AVHR ABS electromagnetic valve, reduce pressure, rear right

AVVR ABS electromagnetic valve, reduce pressure, front right

AVHL ABS electromagnetic valve, reduce pressure, rear left

AVVL ABS electromagnetic valve, reduce pressure, front left

EVHR ABS electromagnetic valve, maintain pressure, rear right

EVVR ABS electromagnetic valve, maintain pressure, front right

EVHL ABS electromagnetic valve, maintain pressure, rear left

EVVL ABS electromagnetic valve, maintain pressure, front left

SPK Accumulator chamber

RFP Feedback pump

RVR Retaining valve

USV ABS or ETS changeover valve

HZ1 Brake circuit 1 of main cylinder

HZ2 Brake circuit 2 of main cylinder

The following operation diagram shows the course of the pressure in the brake system of the “front left” brake circuit with “Reduce pressure” position in the case of ABD or ETS braking.

The changeover valve (USV1) is on standby and in “Reduce pressure” position and the electromagnetic valve (ASV1) in standby position.

The course of the pressure

- The pressure is discharged through wheel valve (EVVL) and changeover valve (USV1), it returns to the main brake cylinder.

- The complete reduction of pressure takes place, in this way, through the electromagnetic valve (USV1).

S42.30-0046-12

Example: Electromagnetic valve (ASV1) in standby position and changeover valve (USV1) on standby and in “Reduce pressure” position

Brake circuit distribution: Diagonal

A2 Hydraulic unit

ASV ABD or ETS intake valve

D Damping chamber

AVHR ABS electromagnetic valve, reduce pressure, rear right

AVVR ABS electromagnetic valve, reduce pressure, front right

AVHL ABS electromagnetic valve, reduce pressure, rear left

AVVL ABS electromagnetic valve, reduce pressure, front left

EVHR ABS electromagnetic valve, maintain pressure, rear right

EVVR ABS electromagnetic valve, maintain pressure, front right

EVHL ABS electromagnetic valve, maintain pressure, rear left

EVVL ABS electromagnetic valve, maintain pressure, front left

SPK Accumulator chamber

RFP Feedback pump

RVR Retaining valve

USV ABS or ETS changeover valve

HZ1 Brake circuit 1 of main cylinder

HZ2 Brake circuit 2 of main cylinder