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Old 13th April 2022, 04:49   #1
macafee2
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Am I right in thinking there are two ABS sensors?
If only two, what happens to the other two wheels?

I had an issue yesterday, braked heavily but not for emergency reasons, it felt as if the front offside locked up and the ABS kicked in but the worrying thing is that the car kept going. It took what felt, a long time for the car to stop.

How does the ABS work, does it release the other wheel on that axle as well as the locked up wheel?

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Old 13th April 2022, 05:55   #2
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One at each corner,the ABS senses the wheel locking up and the pump releases then brakes until the car comes to a halt
This is ABS in the simplest terms sure someone will give you a more detailed description
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Old 13th April 2022, 06:57   #3
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Quote:
Originally Posted by macafee2 View Post
How does the ABS work, does it release the other wheel on that axle as well as the locked up wheel?
No.
When a wheel loses grip and stops rotating under braking, the ABS modulator interrupts the supply of brake fluid to that wheel. As soon as rotation and therefore grip is achieved, the modulator restores normal manual brake function. Usually this cycle repeats very rapidly resulting in the vibration felt at the pedal as the pressure is released and restored at high frequency.
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... but the worrying thing is that the car kept going. It took what felt, a long time for the car to stop.
Yes, that's correct. ABS will stop the car sliding and maintain effective steering but it cannot shorten the stopping distance.

There are four sensors as Popcorn has explained.

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Old 13th April 2022, 15:24   #4
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Quote:
Originally Posted by SD1too View Post
No.
When a wheel loses grip and stops rotating under braking, the ABS modulator interrupts the supply of brake fluid to that wheel. As soon as rotation and therefore grip is achieved, the modulator restores normal manual brake function. Usually this cycle repeats very rapidly resulting in the vibration felt at the pedal as the pressure is released and restored at high frequency.

Yes, that's correct. ABS will stop the car sliding and maintain effective steering but it cannot shorten the stopping distance.

There are four sensors as Popcorn has explained.

Simon
Thanks Simon, it felt as if the other 3 wheels were not braking vey much hence the extended braking distance. At speed no issues. Maybe the road was just more slippery then I thought.

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Old 15th April 2022, 09:53   #5
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I had the opportunity at the transport research lab (TRL) to drive at high speed towards a blow up plastic replica truck, brake hard and steer around it, quite exciting at the time!

Certainly made me feel very confident about ABS systems.
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