[Takumi-san]

The trouble is with the buyers , not the manufacturers / policy makers. It is us who refuse to pay up for safety features. Its us who believe that 'we drive too slow in our country for such things to work' ; its us who will buy the lowest variant of the car or at least the one without the 'safety package' which the manufacturer may have provided. Its from this feedback from us that they do not offer these options at all since they do have a fixed cost and it becomes extremely expensive to offer it to those few who do know its importance. So its the consumer / us who needs this education. We would keep cribbing about higher costs even if this were compulsary. How many of us (general population) wear seat belts because they are something that will save our lives rather than something that gives a reason for the hawaldar to fine us? Shocking replies even amongst my own friends / relatives are that - ' we know no cops on this road , so its ok not to wear seat belts'.

Originally Posted by mail4ajo

Wow.... Someone, please show this video to our automotive manufacturing policy makers, knock on their heads and ask them to make these safety features mandatory on our cars.

In all fairness, I never knew ESP was so important. I only valued ABS. As seen in the video, thats the oldest tech and is now making good inroads in the higher models of our cars. So I guess another decade should see these other techs getting here for those who will pay. Of course by then we should have much more advanced techs in the world which will still have us in India, cribbing.

[magneto]

Hi ,
since we talking about traction , i have been thinking about the traction on front wheel cars .
I travel often on the Pune expressway and my observation is that i see many more fwd cars involved in accidents than rwd cars .
since i am known as a car techi , i was referred to a person who had met with an accident on the expressway .
He is a senior well experienced driver with a very clean record , and his experience which he narrated stumped me .
What he said was that he was at a speed of not more than 90 and happened to go to the right almost say a foot from the end of the concrete ,and suddenly as by some unknown force his steering was pulled from his grip and hit a right turn .
due to this he ended up in the ditch on the right .
there was no damage done to the car and they continued to pune .
the tire also had the right pressure and no defect was found on the car .
I was quite perplexed and could not lay my finger on the cause of this accident ,till recently while traveling on the expressway i noticed that the edge of the road had a buildup of loose gravel all the way .
Then it struck me as to what must have actually happened .
My version is that the right tire must have gone on to the loose gravel making it lose traction whereas the left tire was gripping the road on the left side ,thus pulling the steering towards the right .
I have also wondered as why the Mercedes and BMW have never front wheel drive cars ?
please correct me if i got it wrong there .
I am quite convinced that fwd cars are unsafe for conditions as explained above

[sudev]

Like the previous thread on ABS this is again used more as jargon by sales staff at most dealerships. If you ask them what it is or what does it do? High chances are you will not get coherent reply.

Simply put you are in control of your vehicle as long as tyre surface is moving in sync with road surface.

We saw in ABS thread what happens tyres lock up and surfaces (tyre and road) slip relative to each other - you lose steering control.

Think of traction control as something reverse of braking. When engine puts out more power than tyre is able to transfer to road tyres slip. Lots of smoke and drama happens - think donuts!

However in that slip you are also losing steering control. More slippery the surface - icy or loose dust - more likely the slipping. As long as tyres are pointing straight the problem is almost negligible. However if you are also taking a turn - trying to avoid something - real life drama results. The momentum of car is pushing in straight line but you want to turn. Tyres are spinning do very little control to help car turn.

Again for a good driver this is not insurmountable problem. All you have to do is ease off the accelerator and regain control. However in panic situation average driver freezes and tries even harder to turn.

Traction control comes in to rescue and almost seamlessly reduces power application and help regain control.

How - will describe in next post. How to set up appreciation test also will be described.

[sudev]

So like a skilled driver recovers from loss of traction by easing off on power quickly to regain traction the system for traction control also does the same. Despite your pressing the accelerator - essentially because in fright you are frozen - the system ECU/ECM signals the engine to slow down. Simple.

Yes simple in theory and complex in implementation. The system basically uses sensor from all wheels to detect slippage and then gives signal to engine management to reduce power. More detailed reading can be found on internet.

How to test / demonstrate implications of traction control?

Unlike ABS, where you have to dirty your hands to disable it by removing fuse, demonstrating traction control is easier as most of the vehicles come with switch to disable this on the dash board. Why this is so we will discuss later.

So the test bed set up is relatively easier. You need some open ground with gravel or loose surface as it's easier to create slip with lower acceleration on such surface. Mark a straight of about fifty meters and then a hard right ninety degree turn. Mark with cones only the right side as the left side turn will vary as we run this experiment.

First run with traction control switched on. In first gear take a fast start with accelerator fully pressed. You need to keep the accelerator fully depressed during the turn till you have completed the ninety degree turn and gone say hundred meters. At the end of straight line turn the steering right in attempt to make the ninety degree turn.

If you were fast enough at this time the outer (left) wheels, especially the front, will loose traction. Observe carefully the engine rpm's. Despite your pressing accelerator fully the engine will loose rpm's as traction control taken over. Observe how tight you could corner with traction control taking over.

Now repeat this same run and turn with traction control switched off. In this run you will find the front of car going off a bit on tangential direction and you would complete the turn with much wider arc and no reduction in engine rpm's. The front wheels would be fighting for grip and slipping like mad as they cannot handle the power being put out. If this was a icy surface with higher speed you could have very easily lost control and bumped into something the sidewalk.

It goes without saying that this needs to be done in open and controlled environment. Be aware of others lest you harm them or your self.

Red path with traction control blue without. Engine being controlled can be felt around the turn arc.

So why do vehicle manufacturers provide switch to disable traction control? There are many circumstances where traction control interferes in what you want to do. Say while offroading or on muddy patches.

[devansn]

Thanks for this thread, Sudev.

My car has EBD (Electronic Brakeforce Distribution), but not Traction Control or ESP (Electronic Stability Program). I was wondering how they are different. Or are they just different terminologies adopted by different manufacturers?

Devan.

[prakhar1998]

Traction control is definitely a life saving technology. TCS when coupled with Electronic Stability Control, makes a car much safer, especially in the wet and snow.

I got one of the funniest replies from a Skoda dealership when I bought the Octavia in 2008. They said that TCS is only required in fast cars. I found it so amusing that a car sales executive would not know about this feature, and would tell a customer that the car they are buying is slow

[sudev]

IMHO - EBD is a coupled technology to enhance ABS by constantly monitoring braking force (read hydraulic pressure) and wheel rotation speeds. And adjusting brake force distribution to have even and controlled braking.

[Mpower]

Firstly a TCS or ESP has self-diagnostic capability which means it will check itself every now and then and throw a CEL if it detects anything is off.

TCS can be tested on a loose surface straight line. It makes no sense to risk yourself and your car trying to corner on a dirt road.

Originally Posted by sudev

How to test / demonstrate implications of traction control?

Unlike ABS, where you have to dirty your hands to disable it by removing fuse, demonstrating traction control is easier as most of the vehicles come with switch to disable this on the dash board. Why this is so we will discuss later.

So the test bed set up is relatively easier. You need some open ground with gravel or loose surface as it's easier to create slip with lower acceleration on such surface. Mark a straight of about fifty meters and then a hard right ninety degree turn. Mark with cones only the right side as the left side turn will vary as we run this experiment.

First run with traction control switched on. In first gear take a fast start with accelerator fully pressed. You need to keep the accelerator fully depressed during the turn till you have completed the ninety degree turn and gone say hundred meters. At the end of straight line turn the steering right in attempt to make the ninety degree turn.

If you were fast enough at this time the outer (left) wheels, especially the front, will loose traction. Observe carefully the engine rpm's. Despite your pressing accelerator fully the engine will loose rpm's as traction control taken over. Observe how tight you could corner with traction control taking over.

Now repeat this same run and turn with traction control switched off. In this run you will find the front of car going off a bit on tangential direction and you would complete the turn with much wider arc and no reduction in engine rpm's. The front wheels would be fighting for grip and slipping like mad as they cannot handle the power being put out. If this was a icy surface with higher speed you could have very easily lost control and bumped into something the sidewalk.
Attachment 1249750
It goes without saying that this needs to be done in open and controlled environment. Be aware of others lest you harm them or your self.

Red path with traction control blue without. Engine being controlled can be felt around the turn arc.

So why do vehicle manufacturers provide switch to disable traction control? There are many circumstances where traction control interferes in what you want to do. Say while offroading or on muddy patches.

[sudev]

@Mpower... yes you can do that but what I am describing is to also to appreciate how much difference it makes in control while driving with TCS in traction loss situation. You cannot appreciate that in a straight line acceleration.

[Vid6639]

Originally Posted by sudev

First run with traction control switched on. In first gear take a fast start with accelerator fully pressed. You need to keep the accelerator fully depressed during the turn till you have completed the ninety degree turn and gone say hundred meters. At the end of straight line turn the steering right in attempt to make the ninety degree turn.

If you were fast enough at this time the outer (left) wheels, especially the front, will loose traction. Observe carefully the engine rpm's. Despite your pressing accelerator fully the engine will loose rpm's as traction control taken over. Observe how tight you could corner with traction control taking over.

Now repeat this same run and turn with traction control switched off. In this run you will find the front of car going off a bit on tangential direction and you would complete the turn with much wider arc and no reduction in engine rpm's. The front wheels would be fighting for grip and slipping like mad as they cannot handle the power being put out. If this was a icy surface with higher speed you could have very easily lost control and bumped into something the sidewalk

Sudev, Thanks for the explanation but I'm a bit confused if what you're saying is traction control or ESP (Electronic stability program).

Traction control is different from ESP. Traction control limits the slip of the wheels under acceleration whereas ESP will apply the brakes or cut down engine power when turning.

Example of traction control working is at standstill, if you rev the motor to a high rpm and pop the clutch suddenly. If the wheels are spinning then the traction control is not working or disabled. With traction control enabled the wheels will not spin and the TCS will either apply the brakes or reduce engine power to the wheels to prevent slip.

Traction control also works when cornering but in regular road cars it's rare. When you turn into a corner and then on exit slam the accelerator, the TCS will kick in to prevent wheel slip.

In your example the TCS will not do anything as the ESP will detect understeer and apply the brakes before wheels slip occurs.

When you are cornering and your speed is too much causing the car to run wide or understeer, the ESP will kick in, apply the brakes to respective wheels and bring the car back in line.

Traction control works under acceleration when there is slip whereas ESP will kick in under acceleration or braking no matter what.

ESP looks at the steering wheel angle, lateral acceleration and each wheel speed to work. So if you were to take a turn under acceleration and you start understeering ESP would detect that the steering wheel angle is more than lateral acceleration of the car and kick in. The front tyres may or may not be slipping. Traction control on other hand will work only if the wheel slips.

An excellent example are the F1 cars when TCS was legal. The cars had only TCS and not ESP. The F1 drivers could easily power out of a turn with 100% accelerator pedal pressed. The TCS used to cut in, limiting the power to the wheels optimally. If he went too fast into a corner under acceleration he would still spin out or run wide since the F1 cars had only TCS but no ESP. On the other hand nowadays it's upto the driver to modulate the acc pedal on exit so as to not slip the wheels and spin out.

[sudev]

Originally Posted by Vid6639

Traction control is different from ESP. Traction control limits the slip of the wheels under acceleration whereas ESP will apply the brakes or cut down engine power when turning.

Example of traction control working is at standstill, if you rev the motor to a high rpm and pop the clutch suddenly. If the wheels are spinning then the traction control is not working or disabled. With traction control enabled the wheels will not spin and the TCS will either apply the brakes or reduce engine power to the wheels to prevent slip.

Prevent wheel spin under hard acceleration. No way this can happen till engine power is reduced. SO you agree that TCS will cut off power.

IMHO the stability programs are next level which work in conjunction with all of wheel monitoring, brakes, acceleration, ABS and TCS.

[Vid6639]

Originally Posted by sudev

Prevent wheel spin under hard acceleration. No way this can happen till engine power is reduced. SO you agree that TCS will cut off power.

Yup. Agree with you. TCS will cut off power when there is wheel slip detected but ESP will cut the power when understeer or oversteer is detected.

Under cornering, usually inner wheels will lose traction which will result in TCS kicking in but when you enter a corner faster, it's ESP that kicks in since the outer wheels are the ones that are losing grip.

[VeyronSuperSprt]

The first paragraph is right. The second paragraph is contradicting the first.

[KiloAlpha]

Bringing this old thread to life with this article about the inventor of ESP/ESC.

Stability control has saved countless lives.

The guardian angel that constantly monitors steering wheel angle, tyre grip and the behaviour of cars in corners may be taken for granted these days, but it is widely regarded as the biggest advancement in road safety since the introduction of the seatbelt. Yet few of us realise that it was invented literally by accident.

In 1989, a young Mercedes-Benz engineer, Frank-Werner Mohn, skidded off an icy road in the north of Sweden during winter testing. Sitting in a ditch waiting for a tow truck to be summoned from the nearest town (mobile phones were still an emerging technology back then), he had a brainwave.

What if the recently invented anti-lock brake system – which rapidly pulses brake pressure to prevent locking up – could somehow ‘talk’ to an on-board computer that measured in milliseconds the angle of the steering wheel and the slip angle of a car?

The idea: to moderate engine power and/or activate the brakes on each individual corner to help prevent a skid. Supplier Bosch had a similar idea at about the same time, but its system was activated only when the brakes were applied in an emergency. Mohn’s idea was for the system to be active all the time and constantly monitor road conditions and the attitude of the car. This subtle but significant distinction led to Mohn’s idea becoming the basis for all electronic stability control systems used today.

Full article: https://www.autocar.co.uk/car-news/a...bility-control