Ford Sierra

1982-1993 of release

Repair and car operation

Action principle

Efficiency of braking the greatest, when coupling of the tire with a road surface the maximum. In the course of braking the tire slides on a surface and district speed of a wheel becomes less 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 the pressure created in hydraulic system of brakes so that the size of sliding kept about optimum size (15 %). Action of this system should be immediate and separate for each wheel. The system should answer immediately each change of a surface (factor of coupling) 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 speed of rotation of each wheel of the car in the electronic actuation device.

The electronic actuation device located on the right side under the forward panel, on the basis of received information on unequal speed of rotation of separate wheels (or about their zablokirovaniye) transfers in hydraulic knot of management team of reduction of force of braking (the pressure submitted to a support of a brake) of a wheel which started to test excessive sliding. The electronic actuation device carries out 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 faulty system ABS of a brake nevertheless are serviceable and function as if this system is not present in the car. Only the control bulb warns the driver that the ABS system does not correct his mistakes.

The hydraulic knot of management contains the main brake cylinder of type a tandem 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 force of braking. Three inlet electromagnetic valves during normal braking (without sliding) remain open, 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 will transmit a signal about blocking of the corresponding wheel, immediately the electronic actuation device gives out a signal of closing to the corresponding inlet electromagnetic valve which immediately blocks supply of brake liquid via the brake pipeline to a brake of this wheel – force of braking remains to a constant. If nevertheless sliding proceeds, the final valve and pressure in hydraulic system of this brake opens decreases – the wheel is not braked (surplus of brake liquid comes back to a tank). As soon as the wheel again will start to rotate, 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 an otpuskaniye of a pedal of a brake.

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