ABS - Anti Lock Braking System - Queries

[suvo]

Friends,

Before i come to the topic, let me tell you, I am thoroughly enjoying my stay in this forum and learning things slowly. For example recently, I learnt about how driving a diesel vehicle is slightly different from its petrol counterpart, concepts about idling etc and why they are important. So many thanks for the members for ever helping.

Now coming back to the topic, as I have mentioned earlier, that I have booked a DZIRE ZXI version, so recently decided to do a little reading on the ABS - to know what exactly it is that I am paying for.

More i read, more confusions, I am getting (guess that's why its said that "Ignorance is Bliss" )

Before i come to the questions, let me state my understanding in brief.

Understanding
I understand that in nutshell ABS is a mechanism which prevents the wheels of your car to get locked in case of sudden and panic braking and therefore it allows you to steer the vehicle at the last moment, thereby avoiding a possible collision and also prevents your vehicle in skidding because the wheels are not locked.

Contrary to the popular myth that ABS results in reducing the braking distance, it actually elongates the effective braking distance of the vehicle, because the wheels are not getting locked.

If the above understanding is true, need your knowledge help in the below questions

Questions
1. I have heard and read, that ABS stops working at greater speeds (more than 80 -100 KM/hr). Is it true? If Yes, then why that is so?

2. Also at the same time, I have read or heard that even at lower speeds (less than 20 - 25 Km/hr) ABS doesnt respond well and the driver need to really brake hard to put the vehicle to stop. If this is true, why is it so?

3. When a driver, Panic brakes, it means that the driver wants the vehicle to stop immediately, but if ABS still allows the rolls in the wheels, then how it is effective?

4. As a Driver, what all things, I should know before i drive a ABS fitted Car, OR is there a change in my Driving style needed before I drive a ABS fitted car.

If some of my understanding and questions are completely invalid, please feel free to correct me. I am in some confusion here

 

[nozzlering]

Re: ABS - Anti Lock Braking System - Some queries

We will try to answer your queries.
1. ABS works at all speeds. Its needed more at high speeds.
2. One of the functions of ABS is not to let the wheels skid, at any speed.
3. If wheels are locked during panic braking, the vehicle will skid, swerve and will travel farther than in case of ABS when wheels wont be locked and by the aid of controlled braking, the car will be able to safely stop at lesser distance. Also, the car will be under control of driver.
4. No change in driving style is needed.

All of us have confusions at various levels. We are here to scratch each others' back. Feel free to put queries.

 

[suvo]

Re: ABS - Anti Lock Braking System - Some Queries

Thanks nozzlering, which means, I understood larger part wrong.

What it is made of and how does it work actually. Does ABS gives a feedback to the driver, I mean unless the driver is made to known, are there any ways to understand while driving, whether a Car is fitted with ABS?

 

[autosafari]

Re: ABS - Anti Lock Braking System - Some queries

Understanding

Contrary to the popular myth that ABS results in reducing the braking distance, it actually elongates the effective braking distance of the vehicle, because the wheels are not getting locked.

Not always.
ABS brakes may some times tend to have longer braking distance depending on the road surface (gravel etc.). Also if not properly applied. For ABS to function, brakes to be applied hard and keep on pressing hard. If it is released in between, ABS action won't be proper and take a longer distance to stop.

Questions
1. I have heard and read, that ABS stops working at greater speeds (more than 80 -100 KM/hr). Is it true? If Yes, then why that is so?

2. Also at the same time, I have read or heard that even at lower speeds (less than 20 - 25 Km/hr) ABS doesnt respond well and the driver need to really brake hard to put the vehicle to stop. If this is true, why is it so?

3. When a driver, Panic brakes, it means that the driver wants the vehicle to stop immediately, but if ABS still allows the rolls in the wheels, then how it is effective?

4. As a Driver, what all things, I should know before i drive a ABS fitted Car, OR is there a change in my Driving style needed before I drive a ABS fitted car.

1. Infact the use of ABS is at higher speeds. If it is OEM fitted ABS system, then it will work unless there is some mechanical trouble.

2. For the ABS to function, the pedal has to pressed hard and keep on pressing.

Expert drivers used to apply brakes with a pumping action to avoid locking. ABS system replaces this human effort and does this pumping action mechanically and therefore it is more effective than manual braking.

 

[raj_5004]

Re: ABS - Anti Lock Braking System - Some Queries

1. I have heard and read, that ABS stops working at greater speeds (more than 80 -100 KM/hr). Is it true? If Yes, then why that is so?

Not true. ABS works at any speeds.

2. Also at the same time, I have read or heard that even at lower speeds (less than 20 - 25 Km/hr) ABS doesnt respond well and the driver need to really brake hard to put the vehicle to stop. If this is true, why is it so?

True. I have heard that ABS is not activated below 20-30 kmph because at such speeds, there is no chance of the vehicle skidding out of control. Atleast, without ABS, the vehicle will stop in time.

But in my Innova, I could feel the ABS kicking in at 20 kmph also.

3. When a driver, Panic brakes, it means that the driver wants the vehicle to stop immediately, but if ABS still allows the rolls in the wheels, then how it is effective?

ABS allows you to slow down the car with complete control.

Without ABS, if the driver brakes hard at say 80 kmph and turns the steering wheel, the vehicle will skid out of control.

Atleast with ABS, the car remains in control. So even if braking distance is longer, the driver has the option to steer away the car to safety, which is not possible in cars without ABS.

4. As a Driver, what all things, I should know before i drive a ABS fitted Car, OR is there a change in my Driving style needed before I drive a ABS fitted car.

In a car fitted with ABS, slam the brakes as hard as possible (no need to pump the brakes, the ABS does that for you) and if needed, steer away the car to safety, you wont lose control or the car wont skid.

 

[krish_go]

Re: ABS - Anti Lock Braking System - Some Queries

This is a good set of questions.. It would surly clear pending doubts

 

[suvo]

Re: ABS - Anti Lock Braking System - Some Queries

Not always.

2. For the ABS to function, the pedal has to pressed hard and keep on pressing.

Expert drivers used to apply brakes with a pumping action to avoid locking. ABS system replaces this human effort and does this pumping action mechanically and therefore it is more effective than manual braking.

In a car fitted with ABS, slam the brakes as hard as possible (no need to pump the brakes, the ABS does that for you) and if needed, steer away the car to safety, you wont lose control or the car wont skid.

Thanks Raj, Autosafari - this is good learning. In case the ABS doesnt respond or fails, will the car automatically switch to Normal braking?

How does the whole ABS work?

 

[simha.k]

Re: ABS - Anti Lock Braking System - Some Queries

Suvo, just watch the video. It answers all your queries..


v=ZSqGPyWroesBosch ABS - The advantage - YouTube

 

[allhyundaicars]

Re: ABS - Anti Lock Braking System - Some Queries

Friends,



Questions
1. I have heard and read, that ABS stops working at greater speeds (more than 80 -100 KM/hr). Is it true? If Yes, then why that is so?

one should never pump the breaks or else abs will fail.

one question of my own

can we have aftermarket abs installation ? ( asking both for a byke and a car )

 

[nozzlering]

Re: ABS - Anti Lock Braking System - Some Queries

Thanks nozzlering, which means, I understood larger part wrong.

What it is made of and how does it work actually. Does ABS gives a feedback to the driver, I mean unless the driver is made to known, are there any ways to understand while driving, whether a Car is fitted with ABS?

Already answered by raj and autosafari.

 

[suvo]

Re: ABS - Anti Lock Braking System - Some Queries

one should never pump the breaks or else abs will fail.

one question of my own

can we have aftermarket abs installation ? ( asking both for a byke and a car )

Hey Friend, exact same discussion on another thread ongoing
Fitting Aftermarket ABS – Is It Possible?

 

[mukeshus]

Re: ABS - Anti Lock Braking System - Some Queries

Hey Friend, exact same discussion on another thread ongoing
Fitting Aftermarket ABS – Is It Possible?

Suvo as you understood, ABS has worked at every speed, while I was returning from Goa, I was behind a Auto in front of it a GOA state bus which stopped on middle of road, auto hit the bus.
Even I thought I was about to, but ABS kicked in, it gives you slight pulsation to your right leg thus ensuring its functioning.

However now you are aware functioning you must know what kind of ABS system your car is equipped with.

All cars which have front disc brakes have 3 channel ABS, that includes Scorpio as well.
All the latest cars that have 4 disc brakes have 4 channel ABS.
Where each tyres are monitored by wheel speed sensor.

In 3channel one's the front tyres have individual wheel speed sensor.
Where as the rear ones have shared single wheel speed sensor.

Here is a link where we had discussion earlier:http://www.theautomotiveindia.com/f...involved-driving-non-abs-car-3.html#post88067

 

[suvo]

Re: ABS - Anti Lock Braking System - Some Queries

Suvo as you understood, ABS has worked at every speed, while I was returning from Goa, I was behind a Auto in front of it a GOA state bus which stopped on middle of road, auto hit the bus.
Even I thought I was about to, but ABS kicked in, it gives you slight pulsation to your right leg thus ensuring its functioning.

However now you are aware functioning you must know what kind of ABS system your car is equipped with.

All cars which have front disc brakes have 3 channel ABS, that includes Scorpio as well.
All the latest cars that have 4 disc brakes have 4 channel ABS.
Where each tyres are monitored by wheel speed sensor.

In 3channel one's the front tyres have individual wheel speed sensor.
Where as the rear ones have shared single wheel speed sensor.

Here is a link where we had discussion earlier:http://www.theautomotiveindia.com/f...involved-driving-non-abs-car-3.html#post88067

Thanks Mukesh - Just cross checked with the DZire brochure, it says the Brakes are "Ventilated Disc" at the front and "Drum" at the rear. So in all possibilities, it will have a 3 channel ABS.

Are these ABS system manufactured by the Car manufacturer or they outsource it to other suppliers?

 

[raj_5004]

Re: ABS - Anti Lock Braking System - Some Queries

How does the whole ABS work?

ABS - Anti Lock Braking System.

The ABS has two main components - wheel speed sensors which are attached on each wheel and an ECU.

Wheel speed sensors do the job of monitoring the wheels. If it detects any lock in the wheel, it sends a signal to the ECU that the particular wheel is locking and the ECU will immediately lessen the brake pressure on that wheel for it to stop skidding. When the wheel starts rolling again, it again increases the brake pressure on the wheel. Again the wheels will tend to lock and the ECU will lessen the brake pressure. This happens very very fast, so you wont feel the pumping happening. You will only feel a judder on your brake pedal.

All cars which have front disc brakes have 3 channel ABS, that includes Scorpio as well.
All the latest cars that have 4 disc brakes have 4 channel ABS.
Where each tyres are monitored by wheel speed sensor.

In 3channel one's the front tyres have individual wheel speed sensor.
Where as the rear ones have shared single wheel speed sensor.

Not necessary buddy. Punto has discs in the front and drums in the rear.

It has a 4 channel ABS with EBD. (EBD requires a 4 channel ABS, will not work with 3 channel ABS, since it requires monitoring of all the 4 wheels).

Thanks Mukesh - Just cross checked with the DZire brochure, it says the Brakes are "Ventilated Disc" at the front and "Drum" at the rear. So in all possibilities, it will have a 3 channel ABS.

As explained by Mukesh, 3 channel ABS has 2 sensors on both the front wheels and 1 sensor on the rear axle. The disadvantage is that it cannot individually control one of the rear wheels. Whereas 4 channel ABS has a sensors on all the 4 wheels thereby individually controlling all the wheels independently.

Having discs or drums does not determine whether ABS is 3 channel or 4 channel.

For example, electronic aids like TCS (Traction Control System) and EBD (Electronic Brake Force Distribution) are advanced forms of ABS. All cars will TCS and EBD compulsorily requires a 4 channel ABS as TCS and EBD requires monitoring of all 4 wheels, which only a 4 channel ABS can do.

Fortuner comes with rear drum brakes, yet it has TCS and so it has a 4 channel ABS.

Safari comes with rear drum brakes and it has EBD and hence it will have a 4 channel ABS.

I hope I did not confuse you!

Are these ABS system manufactured by the Car manufacturer or they outsource it to other suppliers?

They are outsourced - most probably Bosch or Delphi.

 

[Sam Dinkar]

Re: ABS - Anti Lock Braking System - Some Queries

Friends,

Before i come to the topic, let me tell you, I am thoroughly enjoying my stay in this forum and learning things slowly. For example recently, I learnt about how driving a diesel vehicle is slightly different from its petrol counterpart, concepts about idling etc and why they are important. So many thanks for the members for ever helping.

Now coming back to the topic, as I have mentioned earlier, that I have booked a DZIRE ZXI version, so recently decided to do a little reading on the ABS - to know what exactly it is that I am paying for.

More i read, more confusions, I am getting (guess that's why its said that "Ignorance is Bliss" )

Before i come to the questions, let me state my understanding in brief.

Understanding
I understand that in nutshell ABS is a mechanism which prevents the wheels of your car to get locked in case of sudden and panic braking and therefore it allows you to steer the vehicle at the last moment, thereby avoiding a possible collision and also prevents your vehicle in skidding because the wheels are not locked.

Contrary to the popular myth that ABS results in reducing the braking distance, it actually elongates the effective braking distance of the vehicle, because the wheels are not getting locked.

If the above understanding is true, need your knowledge help in the below questions

Questions
1. I have heard and read, that ABS stops working at greater speeds (more than 80 -100 KM/hr). Is it true? If Yes, then why that is so?

Not so. ABS NEVER STOPS WORKING.

2. Also at the same time, I have read or heard that even at lower speeds (less than 20 - 25 Km/hr) ABS doesnt respond well and the driver need to really brake hard to put the vehicle to stop. If this is true, why is it so?

As told above, ABS works at ALL speeds.

3. When a driver, Panic brakes, it means that the driver wants the vehicle to stop immediately, but if ABS still allows the rolls in the wheels, then how it is effective?

When a driver panic brakes, he wants to stop the vehicle immediately BECAUSE he wants to avoid hitting something that he doesn't want to hit/going somewhere where he doesn't want to go. Time taken to stop= Distance travelled/speed of the vehicle. ABS cannot overcome this mathematical equation and hence it provides a system whereby the steering is not lost during harsh braking so that the vehicle may still be able to steer away from the obstacle while braking hard. Therein lies its effectiveness.

4. As a Driver, what all things, I should know before i drive a ABS fitted Car, OR is there a change in my Driving style needed before I drive a ABS fitted car.

Do not play around with wheel and tyre sizes- stick to the OEM configuration. NEVER pulse the brake pedal while braking. That's all.

If some of my understanding and questions are completely invalid, please feel free to correct me. I am in some confusion here

Answers are below each of your questions. Hope that clarifies.