Motoring Discussion > Electronic Park Brakes - as emergency brakes Miscellaneous
Thread Author: .... Replies: 16

 Electronic Park Brakes - as emergency brakes - ....
After reading the Stability Control thread got me thinking about features on our cars which I have not used.

I don't remember the Backroom discussing the EPB as an emergency brake.

I had just washed our car which is fitted with one so thought I would try it out.
Off down a quiet backroad, 30mph-ish pulled on the button as mentioned in the handbook and the car pulled up straight, no lock-up, no drama. I tried this a few times on loose chippings/gravel a little quicker again no sideways movement just tracking straight.

I then thought I would try to provoke it so pulled on the button on an open bend where I could see clearly there was no other traffic around. Again the car just stopped, no counter steering required, no sliding, none of the reactions you could expect from a cable operated brake.
Very impressed with the way it just stopped the car, happy I tested it too as it was always a nagging doubt in the back of my mind how it would perform if I needed it in such a way.

The above was done on a quiet backroad with no other traffic around.

EDIT: The above was done in a Citroën C4 GP. Not sure if this representative of how other manufacturer EPB's work.
Last edited by: gmac on Fri 5 Mar 10 at 14:19
 Electronic Park Brakes - as emergency brakes - ....
I mentioned cable operated brake above, it should have read lever operated as in conventional handbrake.
 Electronic Park Brakes - as emergency brakes - oilburner
I'm convinced, it sounds great to me, but I reckon you're preaching to the converted!

Just wait for the Luddites to show up and tell you you're wrong... ;)
 Electronic Park Brakes - as emergency brakes - crocks
How are you supposed to do handbrake turns then? ;-)
 Electronic Park Brakes - as emergency brakes - Zero
how well does it work on a Toyota?
 Electronic Park Brakes - as emergency brakes - Bill Payer
I thought these systems applied the handbrake *very* hard.

In which case I'm amazed that it didn't lock the wheels. Is there some sort of intelligence in the system to prevent that happening?

 Electronic Park Brakes - as emergency brakes - oilburner
I thought the idea was to stop the car as quickly as possible, in which case you want to get to the point *just before* traction is lost, so it shouldn't lock the wheels up at all.

Doesn't locking up the wheels increase braking distance? And it would certainly destabilise the car if it wasn't going in a dead straight line.
 Electronic Park Brakes - as emergency brakes - madf
Almost every car has ABS.

Incorporate that into an electronic handbrake ... and no locking?
 Electronic Park Brakes - as emergency brakes - ....
It does apply the brake very hard, much harder than any lever operated system I've experienced.

There was no pulsing to suggest the ABS was working, no flashing lights on the dash, and no tyre squeal but I would have expected something in an empty 1.5 tonne MPV without some electronic input.

This is on a discs all round system.
I'm not sure if there is a shoe based equivalent available from any manufacturer ?
 Electronic Park Brakes - as emergency brakes - zookeeper
i would of thought it a trifle difficult executing a J turn whilst evading a terrorist/kidnap attempt?
 Electronic Park Brakes - as emergency brakes - rtj70
If the ERB is applied can it be disengaged before the car has actually been brought to a stop. But yes I think handbrake turns and J-turns will be difficult if not impossible.
 Electronic Park Brakes - as emergency brakes - ....
>> If the ERB is applied can it be disengaged before the car has actually been
>> brought to a stop.
>>
That's one thing I didn't try but not an unreasonable thing to do so I will try that and report back, probably tomorrow.
 Electronic Park Brakes - as emergency brakes - -
Interesting this, i wonder if the EPB is linked in with ABS, personally i doubt that i imagine it's either on or off.

As for not locking the rear brakes up with the handbrake, whether electric or not they don't seem so able to do that as cars of yesteryear, whether that was the large drum brakes usually involved or what i don't know.

A slippery track would be a good place to test the anti lock abilities out, don't blame me if the car spins off into the ditch mind.
 Electronic Park Brakes - as emergency brakes - Bagpuss
The EPB on the Audi A6 I had on extended loan could very definitely lock the rear wheels and there was no sign of any input from the ABS. Admittedly I was trying it on a road where the ice had the same texture as glass. Pulling up the EPB lever whilst the car was moving applied the brakes with a ferocity that would be difficult to achieve with a cable operated handbrake, though probably achievable with the footbrake on a Merc, not that I tried.

Above about 30km/h, pulling the EPB lever only caused the brakes to apply momentarily then disengage again, with a warning chime from the dashboard and a big red triangle in the computer display.
 Electronic Park Brakes - as emergency brakes - ....
>> Above about 30km/h pulling the EPB lever only caused the brakes to apply momentarily then
>> disengage again with a warning chime from the dashboard and a big red triangle in
>> the computer display.
>>

With the Citroën you have to pull the EPB lever and keep hold of it for a couple of seconds for it to work as an emergency brake.
I don't know how Audi do it but can't imagine they have no emergency brake.
 Electronic Park Brakes - as emergency brakes - Bagpuss
>> I don't know how Audi do it but can't imagine they have no emergency brake.

You're probably right, it didn't occur to me try that, and I don't have the car any more to try out your suggestion.

I'm anything but a luddite, quite the contrary I'm one of those cash cows known in the industry as an early adopter (despite what Ling thinks about the regulars here;-)). I don't get on with electronic parking brakes though. I still think for automatics the Mercedes foot on/ hand off system is the best - and comes with the benefit of a reassuringly well engineered clonk when you release it.
 Electronic Park Brakes - as emergency brakes - ....
>> If the ERB is applied can it be disengaged before the car has actually been
>> brought to a stop.
>>
Yes it can. It only works as an emergency brake as long as you are holding on to the button. As soon as you release it, the brakes are released.

I still could not provoke a skid though. Tried it at 60mph still no lock up so I think it uses the ABS sensors to provide just the right amount of braking power.
I did manage to trigger the ABS by hitting the footbrake after the emergency brake started working but you would not really do that as you would use the emergency brake due to the footbrake not working.
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