ABS

Snooky

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Can anyone tell me how the ABS works, I want to know how the pick up works, there's a discussion on another forum and I can't answer it, so is it light, magnets, or something else, please inform a very uninformed person...go on please :nenau
 
The sensor is an inductive proximity switch which goes from a 'high' state to a 'low' state ( effectively 'on' and 'off' ) as the ABS ring rotates....thus causing pulses.

The pulses from the front wheel are compared with the pulses from the rear wheel.

Should a wheel approach lock up under braking,the wheel rotational speed will fluctuate and so will the pulse count......front and rear will differ from normal.

The ABS circuitry will then be operated and braking will be 'released' intermittently until the 'count' is normalised.


Put very simplistically.
 
tarka said:
The sensor is an inductive proximity switch which goes from a 'high' state to a 'low' state ( effectively 'on' and 'off' ) as the ABS ring rotates....thus causing pulses.

The pulses from the front wheel are compared with the pulses from the rear wheel.

Should a wheel approach lock up under braking,the wheel rotational speed will fluctuate and so will the pulse count......front and rear will differ from normal.

The ABS circuitry will then be operated and braking will be 'released' intermittently until the 'count' is normalised.


Put very simplistically.
Summary: Magnets and magic.
 
There are two popular types of ABS used
The first type uses an A/C generator which as the wheel rotates sends an a/c voltage to the abs module from each wheel
The second is an on /off type digital switch which has a 5v feed sent to it from the abs module ,this dose not generate a voltage but sends a digital signal on /off /on / off etc as the wheel rotates .This is the best system as the information sent to the abs module is already digital, so the abs module can process it a lot quicker as the a/c type has to be converted to digital information before it can be used by the abs module .
Most abs systems can not generate pressure in the braking system ,it can hold or lower or return the pressure applied to the brake system by the user.
Then we have the powered ABS system which can generate its own pressure this system is used on cars mainly with ESP control which if the car is going out of control can apply any brake in the system fore a fraction of a second to pull the car back in line
Hope this helps :D
 


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