Anti-Lock Braking System; Introduction; Method Of Operation Of The Teves; A.b.s - Fiat Bravo Service Manual

Bravo-Brava
Braking system
Anti-lock braking system
33.
INTRODUCTION
The braking system musfbe rated to take account of the weight of the vehicle when fully laden and the
maximum tyre/ground grip coefficient that may be achieved, in order to bring about efficient slowing
down or stopping in the shortest possible distance and under any driving condition.
However, this is over-rated for the most common conditions of partial load and reduced grip.
Applying the maximum braking force under those circumstances leads to the wheels locking immediate­
ly, resulting in a reduction in the grip-friction coefficient and deterioration of braking efficiency.
In order to arrest the forward motion of a vehicle quickly and efficiently under any contingent situation,
it is necessary to maintain the rolling state of the tyres, despite the fact that, because of design require­
ments, the braking force applied on the friction linings is often excessive in relation to the driving weight
and normal grip coefficients.
It is therefore necessary to prevent the wheels locking by means of an electronically-controlled anti-lock
braking system which is incorporated in the vehicle's braking system.
Since it is not possible to assess the grip conditions in advance, the braking efficiency has to be con­
trolled only after the detection of any effects of initial skidding of the tyre caused by excessive braking
force in relation to the grip coefficient present.
This detection by special sensors leads to the modulation of the braking force by the action of a set of
solenoids and recycling pumps which, driven by a control unit, act on the braking circuit.
METHOD OF
TEVES MK20
(A.B.S.)
OPERATION
ANTI-SKID
OF THE
SYSTEM
The TEVES MK20 anti-lock braking sys­
tem is incorporated in the vehicle's ordi­
nary braking system in order to prevent the
wheels locking during braking.
Its operation is described briefly below.
Block diagram of Teves MK20 A.B.S.
1. Battery
2. Rpm sensor
3. Control unit
4. Diagnosis warning light
5. Relays
6. Recycling pump
7. Modulator
8. Brake pump
9. Servo unit
10. Brake calipers
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