 Anti-lock braking system 2
It is incredibly important to know that a defect in the ABS system does not affect the function of the normal brake. Of course, you may have to adapt a little. But before you as a driver think back to the stutter brake, you would
be better advised to choose a more cautious driving style.
And in principle, ABS is designed in such a way that it takes away braking power and never adds it. There are some things that people do that are too much, and not just when driving a car. But in this case alone, less
would often be more, for example when it comes to speed. And one more keyword should be added: anticipatory driving.
Because it has so few sensors and actuators, a pure ABS system is also quite transparent. It doesn't care why one wheel's speed deviates so much. It uses this fact as an opportunity to reconcile the speeds with those of
the other wheels. And passive sensors were sufficient for the first ABS systems.
At the beginning of this chapter you will see a simplified representation of the solenoid control valves that are preconected of the wheel brake cylinders. The connections are also similar, top left is the (separated) control to
the wheel brake cylinder and top right is the line to it. At the bottom is the connection to the outside air with a silencer.
At the beginning of this chapter you will see a simplified representation of the solenoid control valves that are connected upstream of the wheel brake cylinders. The connections are also similar, top left is the (separated)
control to the wheel brake cylinder and top right is the line to it. At the bottom is the connection to the outside air with a silencer.
The whole part consists of two solenoid valves and two check valves. The former are designed as 2/3 control valves. This means that they not only influence one line, but also replace one possible connection with another.
When energized, both ensure an increase in pressure on the spring side of the check valves, although they are installed in reverse here.
This is now the normal position when braking. The pressure coming from the top left is passed on 1:1 to the top right to the wheel brake cylinder. All paths directly out are blocked.
There is now a need for action here. The wheel in question either locked during the braking process or had a significantly lower speed. Both solenoid valves were accessed and as a result the position of the check valves
also changed. The pressure supply at the top left is shut off and the line to the wheel brake cylinder is connected to the outside air.
Now the wheel is turning again in the same rhythm. Enough pressure has been released. The pressure supply at the top left is still blocked, but by switching off the right solenoid valve, the path of the compressed air
coming from the wheel brake cylinder to the outside is also blocked.
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