Ford Sierra

1982-1993 of release

Repair and operation of the car

Principle of action

Efficiency of braking the greatest, when coupling of the tire with the surface of the road maximum. In the course of braking the tire slides on a surface and the district speed of a wheel becomes less than the speed of the car.

Sliding minimum (0%) when the wheel slides freely, and maximum (100%) when the wheel is blocked. Maximum efficiency of braking is reached when sliding makes 15%. This size also allows to keep stability and controllability of the car.

The role of anti-blocking system consists in restriction of pressure created in hydraulic system of brakes so that the size of sliding kept about the optimum size (15%). Action of this system has to be immediate and separate for each wheel. The system has to answer immediately each change of a surface (coupling coefficient) and load of the car.

Design

The anti-blocking system (ABS) Teves contains four sensors of speed of rotation of wheels, hydraulic knot of management and the electronic actuation device.

Four sensors (at each wheel of the car) transmit the signals informing on the speed of rotation of each wheel of the car to the electronic actuation device.

The electronic actuation device located on the right side under the forward panel on the basis of the obtained information on the unequal speed of rotation of separate wheels (or about their zablokirovaniye) transfers in hydraulic knot of control team of reduction of force of braking (pressure given to a brake support) of a wheel which began to experience excessive sliding. The electronic actuation device performs also autodiagnostic function, warning the driver fire of a control bulb about registration of malfunction of electric chains or elements of anti-blocking system. At the faulty ABS system of a brake nevertheless are serviceable and function as if this system is not in the car. Only the control bulb warns the driver that the ABS system does not correct his errors.

The hydraulic knot of management contains the main brake tandem cylinder which operates forward brakes, and the hydraulic auxiliary device which operates back brakes. The hydraulic auxiliary device contains six electromagnetic valves operated by the electronic actuation device, regulating pressure in brakes of separate wheels and consequently also by braking force. Three inlet electromagnetic valves during normal braking are left open (without sliding), and three final valves – closed. They are located in contours of the right forward brake, the left forward brake and back brakes.

Functioning

When one of four sensors of speed of rotation transmits a signal of blocking of the corresponding wheel, immediately the electronic actuation device gives a closing signal to the corresponding inlet electromagnetic valve which immediately blocks supply of brake fluid via the brake pipeline to a brake of this wheel – force of braking remains to a constant. If nevertheless sliding continues, then the final valve and pressure in hydraulic system of this brake opens decreases – the wheel is not braked (surplus of brake fluid comes back to a tank). As soon as the wheel starts over again rotating, at once there is an opening of the inlet valve and closing of the final valve. Pressure increases in a contour and the wheel is again braked.

Such cycle of braking and free rotation of a wheel occurs very quickly (several times in a second) and proceeds to a stop cars or to a brake pedal otpuskaniye.

The anti-blocking system (ABS) works at a speed of movement more than 7 km/h.