Any - Electronic handbrakes | Motoring discussion | Back Room Forum

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Mon 6 Aug 2018 19:46

Any - Electronic handbrakes - Graham567

I am hoping someone on here can answer a question of mine.

With electronic handbrakes,you apply the handbrake when parked and release it when setting off(or auto release).

My question is what happens in emergency brake failure.The old fasioned way was to dip the clutch and slowly and progressively apply the manual handbrake until the car comes to a stop.

On an electronic handbrake I am assuming it's either on or off? So in the same emergency surely putting the handbrake on would cause the car to stop very suddenly,possibly even causing it to skid or flip?

Or does the car apply the handbrake progressively like a conventional handbrake?

Edited by Graham567 on 06/08/2018 at 19:47

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Mon 6 Aug 2018 20:00

Any - Electronic handbrakes - Metropolis.

I expect this varies from vehicle to vehicle but see this clip of someone doing it in a new-ish corvette
youtu.be/bXCCOo-uTeY

skip to 3 mins in

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Mon 6 Aug 2018 20:44

Any - Electronic handbrakes - Bolt

AFAIA all braking systems are duel circuit so you always have brakes but not as good as all four, electronic handbrake is either on or off and if used while moving locks the rear wheels, IIRC the engine then has to be turned off and back on to reset the hanbrake assy

someone correct if wrong

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Mon 6 Aug 2018 20:54

Any - Electronic handbrakes - gordonbennet

I too would expect a rear wheel lock up if the EPB has enough grunt, certainly very possible on a slippery road..

Luckily i'll never discover if this is the case because i flatly refuse to buy any vehicle fitted with this pointless faff which no one ever asked for.

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Mon 6 Aug 2018 20:57

Any - Electronic handbrakes - catsdad

I am on a slow connection so can't view the clip.

However I would assume that using the handbrake at any significant speed would either be ineffective as handbrakes are relatively puny. However if it did work I suspect it would result in a severe reaction to the likely imbalance across the axle and the obvious imbalance from front to back. Under normal braking most of the effort and effect comes from the front brakes. A handbrake operating solely on the rear brakes is going to struggle to make a safe stop in an emergency.

Don't try this at home.

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Mon 6 Aug 2018 21:09

Any - Electronic handbrakes - bathtub tom

I've only ever driven a Vauxhall with an electric handbrake and that wouldn't let you apply it when moving. Interestingly, operating the button again after it had already been applied resulted in it applying itself even harder.

I suspect not letting you use it when moving would apply to all vehicles. Imagine it going on halfway round a fast bend!

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Mon 6 Aug 2018 21:23

Any - Electronic handbrakes - gordonbennet

Thats worrying BT

it's rare enough but i have had total brake failure in the past, in my sisters Wartburg Knight, fortunately the huge rear drums mad ethe parking brake just about the best i've ever used, and i don't approach junctions at racing speeds so managed to stop.

I would rathe risk a lock up and deal with than have no brakes at all!

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Mon 6 Aug 2018 21:31

Any - Electronic handbrakes - elekie&a/c doctor

Operating the Epb while the car is in motion ,is a lot more involved than you might think. The front brakes will be applied ,as and if required, via the Abs/Aeb brake system.

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Mon 6 Aug 2018 22:05

Any - Electronic handbrakes - Ian D

A few years ago (being an Engineer and all that) I carried out a few tests on a Passat hire car, as I had the same question, say you are a passenger and your driver becomes very ill and you need to stop. I found that if you hold the EPB lever up and hold it, after a few seconds of beeping the handbrake (or maybe as Mr Elekie says the front brakes) violently comes on (don’t try it at home folks.....)

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Mon 6 Aug 2018 23:37

Any - Electronic handbrakes - drd63

My Citroën wouldn't allow the EPB to be applied while moving. I can think of only 1 advantage of a manual handbrake and it's a great shame the youth of today or tomorrow are gradually being denied the chance to perfect handbrake turns. I've gone from EPB to manual and its then you realise what a stupid waste of space it is.

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Tue 7 Aug 2018 00:42

Any - Electronic handbrakes - focussed

That's it - I am definitely never ever going to buy a Corvette if it's got an electroniccy parking brake!

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Tue 7 Aug 2018 07:19

Any - Electronic handbrakes - Oli rag

I tried it on a Renault scenic hire car once. It stopped like someone had stuck a large stick through the front spokes of a pedal bike!

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Tue 7 Aug 2018 07:49

Any - Electronic handbrakes - oldroverboy.

I tried it on a Renault scenic hire car once. It stopped like someone had stuck a large stick through the front spokes of a pedal bike!

Many years ago My cousin Billy was riding his bike down a hill and the brakes were not good enough, so he stuck his foot into the spokes on the front wheel.

Result... 1 broken leg..

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Tue 7 Aug 2018 10:19

Any - Electronic handbrakes - John F

It might vary from one model to another. To answer your questions, here is an extract from my Audi A8 owner's manual....

Emergency braking function

This feature enables you to stop the vehicle if the main brake system should fail or if the pedal is obstructed

- pull out and hold the parking brake switch to stop the vehicle with the parking brake in an emergency

-the brakes wil be released immediately if you release the switch or press down the accelerator

If you pull out and hold the parking brake switch at a road speed above about 8km/h, this will initiate an emergency brake application. The brakes are then applied hydraulically at all four wheels. The effect is the same as an emergency stop (full brake application)

To prevent the emergency braking function from being used accidentally, a warning buzzer sounds when the switch is operated.

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Tue 7 Aug 2018 11:26

Any - Electronic handbrakes - skidpan

That sounds very similar to the one in the Superb, no surprise there. From the handbook

Emergency braking function
If, while driving, a fault occurs in the brake system, the parking brake can be used as an emergency brake
Pull the button and hold (you hear an audible signal), the vehicle starts to brake strongly.
The braking process is interrupted when the key is released or the accelerator pedal is actuated.
WARNING
The emergency brake is to be used only in an emergency when the vehicle cannot be stopped with the brake pedal.

Seems simple enough if an emergency occurred.

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Tue 7 Aug 2018 11:50

Any - Electronic handbrakes - daveyjp

The fact you need to read the handbook from cover to cover to understand how what could be a safety critical system works suggests it is not simple. No doubt there isn't an industry wide standard, so what works for VAG may not be the same for BMW, Ford etc.

When I am given a car with an EPB I am never been given the low down on how the EPB works.

They are cars, not aircraft and KISS should apply, but ever increasingly it isn't, all in the name of progress.

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Tue 7 Aug 2018 12:06

Any - Electronic handbrakes - skidpan

The fact you need to read the handbook from cover to cover to understand how what could be a safety critical system works suggests it is not simple.

I think its fair to suggest that a majority of issues that people have with cars would be answered if they read the relevant section of the manual. But people don't do they, why should they, its just an anoyance having to learn about operating your expensive new purchase correctly and safely.

To be honest I do not read the manual cover to cover because most cars are pretty generic but areas that relate to unfamiliar equipment are read carefully.

They are cars, not aircraft and KISS should apply, but ever increasingly it isn't, all in the name of progress.

If the owner cannot be bothered to read the operating manual you cannot blame the manudfacturer for prividing a product that meets our needs and/or aspirations.

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Tue 7 Aug 2018 13:27

Any - Electronic handbrakes - Andrew-T

<< If the owner cannot be bothered to read the operating manual you cannot blame the manudfacturer for prividing a product that meets our needs and/or aspirations. >>

That is very easy to say, but the fact is that when the emergency arises it is so long after the manual was read that the message is long forgotten. Like so many other things, actions which do not become automatic or intuitive (like riding a bike) become difficult.

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Tue 7 Aug 2018 13:50

Any - Electronic handbrakes - gordonbennet

So the systems are capable of using all the vehicle brakes if i read that right.

Presumably this is via the normal footbrake hydraulic circuit (or how would the front brakes work), but one would only likely use the parking brake in the event of hydraulic failure, in which case one assumes the electric motors that actuate the normal parking brake would still work regardless even though there was no hydraulic feed or pressure available?...though a possible alternative scenario could be in the event of a driver sudden incapacity if a switched on passenger had quick enough reactions which has a lot of merit but how many average passengers would have the foggiest.

In which case i'd rather the parking brake operated on the front wheels instead of the rears, a la proper Citroens of yor.

Still don't want one mind :-)

Edited by gordonbennet on 07/08/2018 at 13:52

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Tue 7 Aug 2018 13:54

Any - Electronic handbrakes - daveyjp

It also assumes the person in the car is the long term owner.

As a driver of pool cars I know how frustrating it can be to even start a modern car, never mind think about how the handbrake may work should I need to slow down without using the footbrake.

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Tue 7 Aug 2018 21:45

Any - Electronic handbrakes - gordonbennet

It also assumes the person in the car is the long term owner.

As a driver of pool cars I know how frustrating it can be to even start a modern car, never mind think about how the handbrake may work should I need to slow down without using the footbrake.

Quite, and one of the joys still of Toyotas heavier 4x4's, always basically simple even if laden with tech it never interferes with the basics, such a relief to get back in to 'does what it says on the tin' when i've had the misfortune to drive any of the company cars/vans with all the unecessary faff.

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Tue 7 Aug 2018 20:33

Any - Electronic handbrakes - John F

<< If the owner cannot be bothered to read the operating manual you cannot blame the manudfacturer for prividing a product that meets our needs and/or aspirations. >>

That is very easy to say, but the fact is that when the emergency arises it is so long after the manual was read that the message is long forgotten. Like so many other things, actions which do not become automatic or intuitive (like riding a bike) become difficult.

There is also the issue of manual length. Mine has 371 pages (and another book of a further 320 pages for the MMI operating instructions). However, on page one it 'recommend that you read this Manual carefully........contains important notes....relative to your safety...'. And there is an excellent index to locate the relevant pages. So, all in all, no excuse not to to have RTFM! Sadly, in the hire cars I have had, never has one been available.

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Wed 8 Aug 2018 07:17

Any - Electronic handbrakes - Falkirk Bairn

IMHO electronic / electric handbrakes are a solution to a problem that did not exist.

Problems with a mechanical handbrake - worn mechanism, a bit of rust or brake cables that need replacing - parts might be a maximum of £200 for cables + labour & can be fixed by somebody on their driveway.

Electronic handbrake could be £1,000+.

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Wed 8 Aug 2018 07:45

Any - Electronic handbrakes - dan86

Problems with a mechanical handbrake - worn mechanism, a bit of rust or brake cables that need replacing - parts might be a maximum of £200 for cables + labour & can be fixed by somebody on their driveway

Whilst I agree with you on this that can't be said for the handbreak on the chrysler grand voyger as when the cabel snaps you have to replace the whole handvreak leaver as well as the cable and the leaver is over £200 from a main dealer ( fitted at a local independent)

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Wed 8 Aug 2018 11:03

Any - Electronic handbrakes - Bolt

IMHO electronic / electric handbrakes are a solution to a problem that did not exist.

Problems with a mechanical handbrake - worn mechanism, a bit of rust or brake cables that need replacing - parts might be a maximum of £200 for cables + labour & can be fixed by somebody on their driveway.

Electronic handbrake could be £1,000+.

Judging by what I have been reading I doubt it will be long before we get electronic calipers, no need for hydraulics then, the epb is just the start of going electric so it will do away with the need for changing dangerous fluids every so often.

it will only need a potentiometer to control the rate of braking according to the how far you press the pedal almost like the throttle....not as easy as it sounds due to the electronics involved but I think it will happen soon

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Wed 8 Aug 2018 12:54

Any - Electronic handbrakes - Andrew-T

<< Judging by what I have been reading I doubt it will be long before we get electronic calipers, no need for hydraulics then >>

No doubt the new-fangled electronic calipers will be 100% reliable. I hate the idea of one failing unexpectedly.

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Wed 8 Aug 2018 17:00

Any - Electronic handbrakes - gordonbennet

<< Judging by what I have been reading I doubt it will be long before we get electronic calipers, no need for hydraulics then >>

No doubt the new-fangled electronic calipers will be 100% reliable. I hate the idea of one failing unexpectedly.

Without a doubt no car i ever own will have either an electric braking system or an electric steering system, i don't mind assistance but i will always want a direct steering link and hydraulic brakes, so if the assistance on either fails i still retain some form of control even if it requires huge effort, and i for one will not be persuaded otherwise.

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Wed 8 Aug 2018 11:31

Any - Electronic handbrakes - veloceman

To be honest I had always agreed with the above.
‘A pointless answer to a problem that never existed’

However I liked the auto handbrake in my Leon.
When I stopped it automatically applied and when setting off it released on its own.

Something less to do when doing hill starts or just plainly setting off from traffic lights, especially if a manual.

Also better for those sat behind not getting blinded by lazy drivers with their foot on the brake whilst stopped.

Car too new to have any reliability problems but no doubt they will be more problematic on only cars.

Sledgehammer to crack a nut? Maybe but I like them.

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Fri 10 Aug 2018 12:23

Any - Electronic handbrakes - Stackman II

It would be nice if all manufacturers could agree on how they should work.

We had a Scenic with EPB and it worked such that when you engaged the clutch it would release, allowing you to pull away and make hill starts. When you came to a halt and switched off the engine it appled the brake. It also had a manual control to pull it on.

When I drove an Audi hire car in Spain I assumed that the brake would apply itself when the engine switched off. Sadly I learned the hard way that it needed to be manually set on parking. Fortunately it only rolled about a foot into the car-park barrier but enough to leave a scratch.

The Scenic brake system became increasingly noisy and eventually failed completely. They are sealed units so replacement was the only option. We sourced a second hand one for about £200 plus fitting. That too failed after about 18 months and another unit was fitted.

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