Electric Handbrake / Emergency brake - Why? 10

[NickJ67]

Whats the reason for manufacturers moving towards electrically actuated, push-button handbrakes these days?

Having recently had to deal with one as fitted to the VW Passat, I have to say that it alone would prevent me from buying/leasing what is otherwise a pretty good car - such a pain to use when maneovering on a steep slope. I have also had the entertainment of watching my neighbor having to deal witha malfunctioning one on her Renault Scenic (non-release scenario).

Seems to me that they must be more expensive to fit and more prone to malfunction than a good old fashioned cable and lever arrangement - what am I missing? Am I a luddite....?

Regards

Nick

 

[dgallup]

JWM

That's very interesting. I've never driven one of these new cars that shuts itself off every time it stops. It makes sense that it would automatically apply the parking brake because without the engine running there is no vacuum source for the brake booster. They have had to significantly re-engineer the starters on these cars because of the much higher number of start/stop cycles. Obviously, the parking brake will have to be significantly improved as well.

I've never heard of cruise control being blamed for more accidents, it has had nearly 100% penetration in the US market for decades with steadily dropping accident rates. Everyone is (rightly) blaming cell phones and texting these days.

 

[Lou Scannon]

"... a recent study reports that drivers using cruise control are significantly more likely to have accidents than drivers without.... "

"I've never heard of cruise control being blamed for more accidents, it has had nearly 100% penetration in the US market for decades with steadily dropping accident rates. "

jmw & dgallup, you both may well be correct. jmw quotes use, while dgallup quotes penetration, which are different criteria.

move along, nothing to see here

 

[jmw]

Well, I now have to find the article I read.
It wouldn't surprise me to learn it is wrong. Several articles appear to suggest it is safer using cruise control than otherwise (except in the rain).
But I while I quite appreciate cruise control myself (especially in low speed limit zones where it is too easy to creep up the speed) I am still not a fan of a lot of these innovation if only that that detract from the driving experience. I really don't look forward to the day when we can put the damn thing on autopilot and let it do the lot.... radar and adaptive speed control... loops under the road surface etc. etc.

JMW

http://www.ViscoAnalyser.com

 

[evelrod]

From where I live, everything worth driving to is at least an hour or more distant. With freeway speeds hanging around 80, I find I use the cruise control almost all the time. Never on surface streets or inclement weather or heavy traffic. Just another convenience of modern autos. Heck, I even use the "cruise control" (hand throttle) on my Model A.
With it on, I can devote all my attention to traffic/road conditions and not worry about the speed.

Rod

 

[patprimmer]

I use cruise control as a safety device. That is safety for my continuing to retain a drivers license. I find they are another step toward being more law abiding but less safe as the mind has nothing to do except think about things not remotely connected to driving the car and I expect greatly increasing reaction time as the conscious brain needs to reboot to driving mode before it can process the urgent data stream to the semi conscious mode that triggered the reboot.

Regards
Pat
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[evelrod]

I've been a good boy, Pat. Haven't had a ticket in 15+ years. The last one was for 95 in a 55. I was going faster but the POS the cop was driving would only do 95. I never even knew he was chasing me.

Rod

 

[patprimmer]

Rod

My father once did something similar.

He was doing about 250kph on an outback road that might have been used when filming Mad Max.

He saw two cars ahead but was past them in a flash. Turned out one was a cop chasing the car in front of him.

The cop called him out a few hours later when he saw him parked in town. Of course it must have been someone else driving another bright red Holden Sandman.

Regards
Pat
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[rmw]

I am not speaking of a modern spring activated brake can. Those will kill you too and I never even thought about taking one of them apart either. And yes, Rod, I have had the pleasure of inserting the "tee" screw and turning that nut ad nausium, only to have to do the rest of the ones on the rig.

I am talking about a cylindrical shaped brake actuator no larger in diameter than a size 30 diaphragm actuator that came on the Belgian made Eagle brand buses that were imported into the USA before they were built in Texas. Those were the days that preceeded the spring activated diaphragm types. When the air leaked down, they locked in place and had to have full brake air application to release them.

This is the modern version:

http://www.tms.org/pubs/journals/jom/9801/felkins-9801.html

or here:

http://www.haldex.com/Documents/hbs...fe_Seal_Spring_Brake_Brochure_L20438_2-08.pdf

What I am referring to looked more like an air cylinder than a diaphragm shaped brake actuator, with or without a emergency spring brake can. It looked nothing like any of the above.

rmw

 

[jmw]

Pat, it is that reaction time that reaction time that was singled out in the article I read... but if the compensating fact is that overall fewer such incidents occur involving cruise controllers, it reconciles the apparently conflicting issues that drivers are safer using cruise control and that cruise control causes accidents.... but this may be a case of journalists not understanding - again.

JMW

http://www.ViscoAnalyser.com

 

[rmw]

I am a feather foot feed control type of driver that can maintain speed as well as a cruise control can although I do let the cruise do the driving when I can engage it and leave it on for a while. I think that is the key to the accident rate regarding cruise's. If you can't leave it on for an extended period, you probably shouldn't be using it.

On the other hand, when driving with the wife (SB to you jmw) I make her use it as often as practical because she drives like her father, (who she and her siblings make fun of); mash the gas, let it off, mash the gas, let it off. The period of her "mashing" depends on the urgency of the situation - in other words, in a tighter driving situation, she pumps it faster. Drives me mad.

I once took a shuttle from downtown Chicago to O'Hare and that gal made the wife look like a piker. I literally got 'seasick' due to the motion her driving created. Wanted to go home and hug the wife.

rmw

 

[jmw]

Reasons not to trust anything electrical when there has been nothing really wrong with the feel of a nice cable operated emergency brake, apart from that it may induce even less concious thinking by the driver.

Firstly, anyone who has experience of early British cares will know all about the Prince of Darkness, Paul Lucas and his car electrical systems. So there is a natural suspicion of overly sophisticated electrical systems where in the past even getting the headlights to shine was a problem.

Secondly, anything with computers naturally involves computer programmers. Then we have the experience of the "blue screen of death and its non-MS equivalents.

Either on leads me to dread the day that my car would find the failure mode that will leave me in a ditch or wrapped around a tree or crunched under an artic.

Let's consider an example.
The Citroen C5 has 9 computers on board. This was a major feature of their advertising.
I had one.
Not the earliest but not long into the life of this model.

I would be driving along at night when I'd note a flicker of the headlights as if they'd momentarily gone off and on again.
They had.
In earlier models it was even more alarming as they might go off for an appreciable period of time - when hacking along an unlit road at night and at 100-110mph, appreciable can be quite short but very scary.

Note that they didn't fix the problem properly in one go because my version still had the momentary flicker (which can be both worrying and distracting until you know what is going on).
Every time you went for a service they'd update the software.... so eventually and after who knows how many iterations, they did fix it.

The C5, like many of the Citroen cars has hydraulic suspension.
The engine drives a compressor which charges the reservoir which supplies the braking and suspension systems.
When the pressure starts to get low the compressor kicks in.
It apparently draws something like 60amps.

Now, the alternator is not always on.
When the battery is fully charged it is de-clutched to ease the load on the engine.
So if you are driving along at night with the alternator de-clutched and the compressor suddenly cuts in, it hogs all the battery output and the lights go out. Then the alternator cuts in, the lights come back up and you start breathing again.

It seemed to take forever to finally get the system to work in such a way that when the pressure dropped, the alternator come on first then the compressor could run. One guesses that at first they tried simply to synchronise the two which is why I got the flicker, but in the end it was a do this first then do that solution.

Oh yes, suspension. AT speed the computers adjust the suspension for "better" handling. This also includes lowering the front end of the car a trifle. Or that was the intent. They discovered with mine that at speed it raised the front end of the car.

So now we have a sophisticated electric/electronically controlled emergency brake system and I should trust it?

What was wrong with cable systems and lever or a foot pedal? (I prefer the handbrake version myself either conventional or fly-off).
While one might suspect self-adjusting mechanisms especially if old and full of dirt, they can be effective and you know from the amount of pull up on the handbrake lever when the cable has stretched or the system needs adjusting. Apart from the cable snapping, which you will know about when it happens, this is a relatively simple and understandable system (more complex with disc brakes all round), and still relatively fool proof.

If you are going to mess around with it, don't call it an emergency brake system any more.



JMW

http://www.ViscoAnalyser.com

 

[MikeHalloran]

ISTR the inventor of darkness was Joseph Lucas.



Mike Halloran
Pembroke Pines, FL, USA

 

[jmw]

I will keep getting him mixed up with Paul Dukas who wrote "The Sorcerer's Apprentice" (familiar to many of you from either a Mickey Mouse or a Tom & jerry cartoon... I can't remember which....)
Thanks Mike.

JMW

http://www.ViscoAnalyser.com

 

[Pud]

I have been driving since 1967 - I cannot recall ever having to use the "emergency brake".

I have an Audi with the electronic handbrake and the (switchable) brake assist (or whatever it's called)and I rather like it. It's not a stop-start model (manual gearbox).

Ok, if it fails in an emergency, I guess it's no worse than a corroded handbrake cable snapping when yanked up sharply.

H

http://www.tynevalleyplastics.co.uk

 

[FreddyNurk]

31 Mar 11 19:10
In Australia at least, any car over 3 years old needs a safety inspection that includes hand brake operation every year before you can renew your registration. Also we do not need to apply salt to roads. Also handbrakes are nearly always used every time the car is parked so a failure through corrosion or seizing is unlikely and other failures are likely to be promptly fixed.

Also to acquire a license to drive in Aus, you need to pass a practical test that involves correct use of the handbrake. Failure to use it correctly even once gets you failed in the test.

As a point of reference, rather than adding too much to the discussion, Queensland doesn't have the same inspection requirements as the rest of Australia. Its probably why more busted arse heaps of junk are seen here than in other places (including, believe it or not, Northern Territory).

I ended up being one of those talented people that don't use the handbrake for hill starts, mainly as I learnt to drive on a 15 year old Urvan that had a hard to disengage handbrake and a column shift manual.

I can see an electric park brake being more useful on something like the new DSG gearbox equipped VWs, apparently they still don't behave as the general public expects an 'automatic' gearbox car to behave, though admittedly I've not driven one.

 

[Gearloose1]

There is room for a much more broader discussion of the role of manual (mechanical) vs. electronic controls.

I may be a lone voice, but am of the view that we have gone way too far toward electronics, and in the process, sacrificed reliability and often, progressive failure (with warning), and many other characteristics inherent in mechanical controls for the programmability of electronic controls.

For example, what is the cost / benefit of trading the tried and true ignition key (mechanical) with the electronic "start" button?

What would be the tradeoffs of trading off the mechanical steering linkage with a electrically activated one?

 

[NormPeterson]

Automotive Engineering Other Topics is probably where a more general discussion belongs, though as a stand-alone topic it might get red-flagged. I'm sure if you poke around in the various automotive fora you'll find a range of opinion.

Cost/benefit tends to get a bit skewed once you include a factor for sales captured from the guys who didn't offer whatever feature, or sales lost because you didn't and your direct competitor did. Whether it's necessary or even a good thing from a technical point of view (such as your 'press to start' or being able to leave the key in your pocket) is rendered irrelevant.

Electronic involvement as a result of mandated systems is probably unavoidable.


Norm

 

[evelrod]

I have observed that the 'younger generation' simply don't savvy the mechanical/manual operations. With that in mind, I'm guessing the future of our transportation is in the hands of this same 'younger generation' leaving me with little hope of seeing any mass reversal of the trend to electronic 'everything'. I must admit, even at my age, I find the new cars overwhelmingly better than those of yesteryear...and I love all my old vintage cars, they are just NOT anywhere as reliable and convenient as what is on the market today....Warts and all.

Rod

 

[rmw]

Rod,

Are you referring to the bunch that don't know how to dial a rotary phone?

rmw

 

[evelrod]

I'm referring to the kids that see my 1939 Bell and my 1909 Northern Electric and ask, "Are those real phones? How do you make them work?"

When we have a power outage, they are the only phones that work. All my digital phones need power. It is reaching the point where we will just not need a land line any longer. Most all of the calls my family make are on their cells. I'm the throwback. I get yelled at all the time for "...going off without your phone. What if something happens?"---

Rod