Electric Handbrake / Emergency brake - Why?
Electric Handbrake / Emergency brake - Why?
(OP)
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
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





RE: Electric Handbrake / Emergency brake - Why?
Had a mech e brake freeze up this winter on me. When I tried to go, the differential kicked, and I didn't have enough traction to drag the locked wheel. Finally rocked it enough to get the car moving and drag the locked wheel till it freed up. Good laugh looking back.
RE: Electric Handbrake / Emergency brake - Why?
I will also be eliminating vehicles so equipped from my short list, because:
- I'm guessing (again) that they're impractical to use for slowing the car down without energizing the brakelights, as is occasionally desirable.
- They're already demonstrating a finite failure rate.
- They're going to be expensive over the parts counter.
Mike Halloran
Pembroke Pines, FL, USA
RE: Electric Handbrake / Emergency brake - Why?
Rod
RE: Electric Handbrake / Emergency brake - Why?
"- I'm guessing (again) that they're impractical to use for slowing the car down without energizing the brakelights, as is occasionally desirable."
I won't be buying one of these soon either but to me it's a lot less serious than the little rat fink black box spy's they are building into most new cars.
RE: Electric Handbrake / Emergency brake - Why?
My guess is that most drivers don't really use them any more, except as park brakes.
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
I would opt out of it if I could, but it would not be a major factor in my choice of a new car.
A lever to control a linear motor would be real nice especially if there was a feed back device for real feel in the lever.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
More Murphy...."If it can go wrong, it will"!
Rod
RE: Electric Handbrake / Emergency brake - Why?
But every summer, I go to upstate NY, which has fairly serious grades, even in places where you'd like to park. E.g., the ancestral home's driveway is steep enough that it's very difficult to disengage an automatic's parking pawl unless you seriously applied the parking brake before engaging the pawl.
I don't terribly mind using the service brakes' friction surfaces for a park brake, as used to be standard here in The Colonies, but I have a serious problem with relying on their hydraulics for that purpose. Of course, this kind of crap is never an issue while the car is in warranty and uncorroded, so it may be forced down our throats, but I'm not happy about it.
Mike Halloran
Pembroke Pines, FL, USA
RE: Electric Handbrake / Emergency brake - Why?
Useful for: Getting a car to turn when it doesn't want to (plowing straight on a slippery surface), getting a car to stop when the ABS won't let it (building up a wedge of snow or gravel in front of a locked wheel helps).
I doubt if the pushbutton/electronic method will overrule the ABS ... and you can't modulate it.
RE: Electric Handbrake / Emergency brake - Why?
I like to think of myself as a crack engineer... Are we going to have to take this to the pub?!!
RE: Electric Handbrake / Emergency brake - Why?
I have seen designs that were incorporated in the caliper, but I suspect that laws requiring separate cable and hydraulic actuation of brakes may be preventing that from hitting the roads, if it's not out yet.
RE: Electric Handbrake / Emergency brake - Why?
Mike, have you been moon(shine)lighting again?
"My guess is that most drivers don't really use them any more, except as park brakes."
Oh, Greg, how could you say that? Though it is probably true, given that 99% or so of US drivers won't or don't know how to drive a stick. I use mine pretty often, but then, I drive a stick in a hilly area.
RE: Electric Handbrake / Emergency brake - Why?
- Steve
RE: Electric Handbrake / Emergency brake - Why?
I get that there are likely to be some design and assembly benefits. There may or may not turn out to be any maintenance & repair benefits; I think it's too soon to tell. But a secondary braking system is something that should first and foremost be user-friendly.
If the buttons aren't located any better in other cars than the one in my wife's new Subaru is, they'll be all but useless in an emergency. Down on the left side of the dash, nearly out of reach, not where you need to be looking when you need it in a hurry, and not something you should be wasting any time fumbling with. If you ever wanted to get people away from using anything but the footbrake, this seems as good a way as any to go about it.
I don't like it at all, for the above plus most of the reasons already mentioned. But I suppose that it gives away less functionality - at least with respect to getting a car to turn in on a slippery surface - with that car's AWD than it would with anybody's FWD.
I think the manual means of releasing the Subie's P-brake involves 200 revolutions or so with a little hand crank that fits into something down under a body plug. Even though I rarely use any P-brake - no thanks.
Norm
RE: Electric Handbrake / Emergency brake - Why?
Down the track you could imagine getting rid of the thing entirely, and using the ABS pump to keep the brakes energised when parked. That gets rid of the redundant system of course, but we don't have a redundant steering system, and that is more important.
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
Certainly if there are at least two circuits that work independently if a hydraulic or electronic system fails you have redundancy foe everything downstream of the pedal mechanism.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
This appears to be one of those "solutions in search of a problem" deals.
Rod
RE: Electric Handbrake / Emergency brake - Why?
To get around this PBR and others introduced a separate drum brake, manually activated. This was a bit nasty package wise, and of course had all the problems we knew and loved with any manual park brake system. I also doubt it was much chop as an emergency brake.
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
Mike Halloran
Pembroke Pines, FL, USA
RE: Electric Handbrake / Emergency brake - Why?
Further, it is interesting than a number of people on this forum understand, in ordinary circumstances, electronic parts are much more reliable than mechanical parts, but for some reason in this thread we seem to be going back to old school mechanical parts are best. I understand that, if a parking brake is a new implementation, the electronics may not be worked out, but in the long run I would put my money on the electronics being more reliable.
Accordingly, I can only guess this thread is a bit of nostalgia for a simpler time when a man could back up a trailer, parallel park the Titanic, and, yes, perform many stunts with the hand brake that come up in everyday driving situations.
The reason for this trend, if it exists (I've not personally noted electrical parking brake switches yet), is switching to an electronic part gets rid of one more mechanical point of failure, so there is some updside.
The downside, or "risk," is non-existent. First, the number situations where the hand brake makes a difference exists are few, only a tiny fraction of the population is even competent to work the hand brake, and in the rare case where the situation and driver line up, the mechanical hand brake is probably not up to the task anyway. Second, if a driver has the knowledge to understand that he is in a situation where the hand brake is helpful, he is competent to use it, and he has the reaction speed and skill to use it properly, that driver is no doubt also skilled enough not to get into the required amount of trouble in the first place.
RE: Electric Handbrake / Emergency brake - Why?
Solid state electronics have proven themselves time and again to be much more reliable than any mechanical device.
Agreed, at the chip level.
But that's not a fair comparison. At a system level, electronics include connectors, of many sorts, living in many environments, and frankly they haven't done so well.
See 'tin whiskers'.
See 'intergranular corrosion of tin'.
See 'age-related annealing of low-force connectors'.
Somewhere out there in time, probably well under ten years, connectors that carry substantial current, even intermittently, like the ones that apply and/or release parking brakes, fall below the reliability/ availability of mechanical devices like handbrakes.
Mike Halloran
Pembroke Pines, FL, USA
RE: Electric Handbrake / Emergency brake - Why?
Mechanical systems don't have to rely on something as fragile as a fuse or a connection that might not be as corrosion-resistant as expected, and generally you get some warning before mechanical things stop working entirely. It may be only a few cycles from "something feels different" to "uh-oh", but that's still better than a binary "here this time, gone the next".
I can only speak for the Subaru version (2.5GT/265HP/6-speed manual - the wife's car) here. But having to be depressing the brake pedal in order to apply the P-brake is at least as clunky than working a foot-operated manual P-brake, in exchange for which you give up the ability to modulate it at all. When I use a mechanical P-brake, I tend to use only enough to get the job done, rather than yank on the handle or stomp on the pedal for all I'm worth every time, which may indicate something.
Supposedly, the e-P-brake is self-releasing on throttle pedal motion as you drive off, but I have found that this is not always the case. Yes, I have used it a few times, enough to find out that much, and the fact that it's a bit slower to get the job done than any mechanical system I've ever dealt with (which is another little irritation I'd just as soon live without).
I do find it interesting that the recommendation for (temporarily) dealing with an inop electronic P-brake is to stop on flat ground and put a manual transmission car in either '1' or 'R' or an automatic in 'P'. I guess the Owners Manual writers aren't allowed to assume that the video-game generation has much grasp of things mechanical other than pushbuttons.
Norm
RE: Electric Handbrake / Emergency brake - Why?
Some older brake cans had ratchet mechanisms in them that required a full application of air to release the brakes when the park brake wanted to be taken off.
In those systems, a failure of air immediately results in the onset of braking driven by high pressure springs whether it is wanted or not. The spring cans have the ability to be manually jack screwed to release them at which time there are no brakes.
I think Electonic brake systems will have to have some type of analogous provisions.
rmw
RE: Electric Handbrake / Emergency brake - Why?
There is a world beyond the borders of the USA.
In this world beyond the USA, at least in the English speaking parts, emergency brakes are normally called hand brakes because they are operated by hand. The lever that operates them is normally between the two front seats and is close to the gear lever and in a position that is very convenient and intuitive to those who drive a manual transmission. A foot operated emergency brake while OK on an automatic, when near the clutch pedal would be somewhat problematic re space and avoiding accidental application when intending to disengage the clutch. Also the quick release nature of foot operated emergency brakes makes hill starts very difficult.
Outside the USA there are many countries where a manual transmission is standard equipment on cars designed for mass consumption. In these countries they are not reserved for econo boxes or crazy street racing types of markets or gear head/petrol head/rev head or whatever you like to call them types of customers.
Just in case you never saw a hill start with a manual transmission, most drivers when starting facing uphill apply the hand brake, engage low gear, use the right foot to control the throttle, the left to control the clutch and their hand to control the hand brake and co-ordinate all three to take up the load before releasing the brake to take off smoothly without rolling back.
Unless you are among the few who have the skill to "heel and toe" it, this maneuver is pretty much impossible with a brake that is not controlled by hand and does not have a progressive control of holding power that can be felt.
I do agree that a hand brake lever between the front seats intrudes into potential cup holder real estate, or even reduces console storage space, however that space has no other useful options that I can think of that could not also be placed under a seat. I normally place the cup on the seat between my thighs
I also agree that routing cables around tail shafts and exhaust pipes and suspension components can be difficult, especially with all the other bits that now occupy the area near the hub.
I have personally never in over 40 years had a handbrake mechanism fail. I have twice used the hand brake to stop when the hydraulic system or the spring between the two pistons in the split circuit master cylinder failed. Even if only the rears go, the car where it happened to me still stops but stops poorly with fronts only as the pedal still hits the floor at a moderate rate of braking. Applying the handbrake at that time almost doubles the stopping power.
In other parts of the world we do still travel on gravel and even on tracks. Hand brakes with progressive action and feel have a lot of benefit in those situations.
The best option for off road use, although I have never seen it supplied as OEM equipment on a passenger car and rightly so because of minimal requirement from the market, is individual hand brakes on the drive wheels if it is a rear wheel drive. It is standard equipment in foot operated form on tractors. I guess fancy traction control does the same thing for you on modern top end models by applying brake to the wheel that breaks traction.
Mike and Greg
I prefer the small drum vs the mechanical secondary operation of the caliper piston. In my experience it still provides enough brake to save the day in any recoverable situation. It just turns a normal stop into a panic stop and maybe a life threatening crash into a fender bender.
I know this is an abuse of the brake system, but I also at times push my pad life to the max and only replace them when I hear some scraping. When I hear it I try to complete the journey using only the hand brake so as not to score rotors, then replace the pads with the set I carry in the car when convenient. This is possible with an old fashioned hand brake.
If you drive a manual transmission and you apply a well designed hand brake properly when parked, you would normally stall it on the first takeoff attempt and that certainly reminds you to check that you released the brake. Anyone who half applies or half releases a hand brake so it can be driven easily but still overheats, probably should not be allowed to use public roads anyway.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
To contribute, I'd always take the feel of a hand brake vs the convenience or reduced cost of an electronically actuated brake. And I agree with Mike - solid state electronic components do have a higher reliability, but the mechatronic components to go along with them don't.
Kevin Irrer
Northville, MI USA
RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
I guess I'm in the minority here because I've yet to need the parking brake during a hill start in my manual equipped vehicles.
RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
Kevin Irrer
Northville, MI USA
RE: Electric Handbrake / Emergency brake - Why?
Every car I've owned before the year 2000 had a failed brake. Usually, a previous owner drove with it engaged. It would hold a parked car generally, but was worthless as an auxiliary braking device. Granted, we're talking about a long line of old, crappy cars.
@Mike - you are a serious outlier. But let's also not forget that, skilled driver you are, you have other options. The hand brake just happened to be the one you used in the two situations you are referencing. Even if you would have died due to a lack of a hand brake, it wouldn't be "your fault", it's just that you would be dead and someone else would have taken away the thing that would have saved you, for the reasons I mentioned. It's unlikely they could have been held liable. The OP was asking why this happened, not whether it was the best idea. My point is, from a liability standpoint, it makes a lot of sense.
@PatPrimmer - my first car was a '77 Camaro with a (failed) parking brake, a manual transmission, and the car would not idle without periodic stabs at the accelerator. There were a lot of hills at stop signs in my town. My point is not that my life would not have been easier with a working hand brake, my point is that car companies are not worried about me.
My brother had his brakes fail in an old car and tried to slow himself with the hand brake. There was a little early success, then something broke, where the lever lost tension and the brake locked his wheel and flipped his car into the ditch (he was OK).
Imagine if a car company were to bill their inclusion of a hand brake as a safety device in their car. Now, incompetent consumers are incorrectly using it, and further it becomes a maintenance device. Better from a liability standpoint to call it a parking brake, and essentially disable it for all other purposes. Now that's a USA-centric viewpoint as well, but based on the OP asking why an electronic brake switch is replacing a manual, I assumed we weren't talking about Sierra Leone here anyway.
Another question - where hand brakes are billed as a brake to be used in non-parking situations, do they apply braking power to more than a single rear wheel?
RE: Electric Handbrake / Emergency brake - Why?
I don't mean to pick on you Steve but...This statement says a lot more about you than the cars you chose to own!
Pat, driving a 1930 Ford daily, I find the hand brake invaluable.
I've only had two complete brake failures in over 50 years. The first was in 1958 in my '49 Merc and the other was the e-brake of my '83 Turbocoupe. Maintenance and common sense come into play here, admittedly in short supply in these days of 'big brother'. My wife likes all the convenience of the electronic revolution in automobiles...I find it a bit 'off putting'.
Rod
RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
I think Pats last post was a nice summary of my feelings on the matter.
Here in Euroland (and most places outside the US maybe) stickshift forms the majority and a handbrake is pretty much essential for hill starts for all those not unusually gifted with heel & toe skills. Certainly that is the way that new drivers are taught in the UK and I believe that you are not allowed to take your driving test in the UK in any car equipped with an electric parking brake.
On the Passat I drove, there was no "Hillhold" feature. I understand that it could be been specified, but at substantial extra cost. Can't comment on the "hillhold" as I haven't tried it - seems like an essential feature though. All I can say is that manoevering this car in a cramped car park on a hill with this fiendish device made me feel like a complete muppet - and it was ably assisted by the 2.0TDI engine having virtually no torque just off idle and a particuarly daft "key" arrangement that makes a rapid restart (after the inevitable stall) impossible.
So to me, seems like a considerable backward step in usability, added complexity and certain to cause all kinds of issues as these systems age.
With the exception of my fathers Peugeot 404 wagon which had a peculiar under-dash arrangement (and a column change for extra oddness) every car I've driven, manual or auto, has has a handbrake lever between the front seats. Can be used for parking (assisted by leaving in gear or P), slowing without lighting the brake lights (ahem..), handbrake turns, and once only for me thankfully, to bring me to a halt when nothing else worked.
Electric handbrakes seems like an addition for those who possibly should never be allowed a licence in the first place....
As for the emergency brake role - I have had total brake, ironically only on a car with dual circuit and ABS and the manual handbrake was a big blessing. I'm not sure how these electrical versions react to being applied while moving, but I think I'd rather have the control myself.....
Nick
RE: Electric Handbrake / Emergency brake - Why?
Interestingly, both times I had partial brake failures that required hand brake assist was in mid 80s Aussie Ford Falcons out of the company pool. Both had high mileage and where in the pool because the normal operator had received his replacement.
The cause seems to be a weakness in this particular model which was a failed spring in the master cylinder so that pedal pressure was not applied to the back brakes.
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.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
I do think that you needed to work on your Camaro's driveability issue. Even the nasty-cammed engine I built up as a know-enough-to-get-myself-in-trouble 20-something wasn't nearly as cranky as what you describe, and mine only had four small cylinders.
Here's what New Jersey has to say about "E-brakes" and the driver exam - from the State DMV official site, "What to bring to a road test" . . .
No way would the Subaru pass muster.
I remember taking my own driving test - had to successfully execute a K-turn on a hill with the examiner sitting right seat (with dual brake and clutch pedals). The object, of course, was to demonstrate that you possessed a certain level of car control, and I think if you touched either curb even lightly, you failed.
You and Pat must live in substantially hillier/mountainous regions than I ever have or have ever driven through. I might have used the P-brake to get started from a stop on a hill all of a dozen times over the last 40 years, and I can't even remember when the last time was. I doubt that my wife has used it any more frequently. You do need to know that we've owned manual transmission cars exclusively since about 1972.
So the hill-holder feature on the Subaru is wasted tech as far as we're concerned, but at least the button to activate it is an even longer reach than the electronic P-brake. Thankfully, its default = off. I'm probably giving an impression of regret for having bought it, but aside from these two (and a couple other minor but mandated) "warts" it really is a nice car.
I get that we're outliers at least within the US market. But driving a stick-shift car just isn't that difficult.
Norm
RE: Electric Handbrake / Emergency brake - Why?
I grew up in hilly terrain driving manual transmissions and have driven my share of manuals all through my adult life even after I began to drive automatics well into adulthood and I rarely if ever used the hand brake or emergency brake to assist me on a hill take off. Probably because they were located in such a way that they were intended for parking, not hand use.
I commonly drive manuals in countries other than the USA and likewise, I managed to get going on hills without having to resort to the hand brake or emergency brake. If I remember correctly, in England with the RH drive cars, the hand brake is on the same side as you are trying to shift with.
But I never would say never, and there have been a few occasions where it came in handy and I used it but they were rare. So it is not like I haven't done it or don't know how. It just wasn't taught to me when I was learning to drive as a technique and I just didn't practice it. Now, riding the clutch...... well that's another topic.
I have driven tractor trailers with manuals ranging from 10 speeds to 18 speeds and motor coach sized buses all with manuals ranging from 7 speeds to 4 speeds all with air brakes and there was no "hand brake". Plenty of that driving was in the Rocky Mountains. The parking brake as mentioned in my previous post was a pneumatic device that was either full application or off, not something that could be manipulated as a 'hill asssit'. In those beasts, you just had to have the skill to get off the brake and feather the fuel without killing the engine or breaking the passengers necks. And, no I never broke any necks, but yes, I did kill a few engines over the years. Embarrasing.
So I'm not buying it.
I did have one vehicle that had hand brakes and I say brakes as it was an Impy Sporster metal body dune buggy built on a shortened VW frame and the emergency/parking/hand brake was two handles (yes, between the seats), one connected to each rear wheel. When grabbed and yanked in a tight turn, it would make that DB spin on a dime. Fantastic.
Maybe I need to go back and learn how to drive all over again.
rmw
RE: Electric Handbrake / Emergency brake - Why?
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
I learned to drive in tractors and dump trucks, and had quite a bit of off-public-road time on them before taking my driver's exam. During my first trip in a manual-transmission car for driver's ed course, I naturally did a heel-and-toe (or more likely just a quick-dip start) on a hill. The instructor chuckled, said he remembered now what my last name was (brother and sister had both driven with him), and made me go back and demonstrate a parking-brake start on a hill. He claimed that not doing it that way during a driver's test would result in points off.
Nowadays, on some hills around where I live, I still use the handbrake to start off. Not so much in my pickup truck, as it's got a foot-applied e-brake. An e-brake start is a little easier on the clutch, I think. I also tend to leave a good 10 feet or more when stopping behind a truck on a hill, just in case that driver isn't very good at hill starts and rolls back a bit. I've seen a few cars take a roll-back hit around here.
RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
RE: Electric Handbrake / Emergency brake - Why?
When I had a manual transmission company car, I was quite amazed at how many could not actually drive it when it had to do pool car duty and that was in Aus. I believe from anecdotal evidence it is even worse in the USA, but better in Europe.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
I read one newspaper account of a Greyhound Bus driver who was having trouble with one (Greyhound - an all automatic tranny bus company bought Trailways, an all manual tranny bus company and inherited a lot of buses with manuals) and a woman passenger came off the seats and volunteered to drive it (from Roanoak, VA to NYC) and he let her. He was fired upon their arrival.
I'd say the vast proportion of the population can't drive manuals and as soon as my generation dies off, that goes way up.
Some of the little fuel efficient "wind-up" cars are bringing it back somewhat, however.
rmw
RE: Electric Handbrake / Emergency brake - Why?
Saying nothing about the repair costs for all the little electric specialty boxes, and transducers.
RE: Electric Handbrake / Emergency brake - Why?
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
The two main arguments were:
1: Interior Design/Safety
2: Old lady´s and such havent got the muscle to safely apply/disengage the handbrake.
other arguments:
3: You could incorporate some safety features such as hill start assist, automatic apply at red lights, connect the brake to the car theft system etc.
4: more freedom in packaging
At that time (10 years ago)it was hard to interpret the legality rules regarding handbrakes. Yes it was to be standalone , yes it was to give this retardation and be able to hold a car in a certain slope and it should be functional below 30 km/h.
one question we discussed a lot was the potential problem with wheel lockup when applying the brake... whas that acceptable even in low speeds ? ... the law didnt say.. just minimum retardation
Another question was how hard the brake should be applied: too hard always would give certain problems and too loose would give other. That brought us to next problem: How was the brake force measured and was it a reliable method ?
Other problems were safety related since the brake NEVER NEVER EVER was allowed to engage by itself when driving.
All the designs we looked att incorporated some kind of microprocessor with a watchdog.
We focused/looked on three designs.
One german design didnt really have force control and applied full brake always ... skipped immediately (the design didnt really allow for force control)
One american design consisted of a motor and a screw that pulled one wire which was divided into two wires with a "lever" (cant come up with the english word for it now). Basically you replaces the brake handle with an electric motor with a gear.
Seemed reliable enough.. however the product wasnt mature enough.
Another german design was really sexy it pulled both wires with the same force guaranteed. It had a REAL force sensor, instead of the other solutions that measured current draw/voltage.
It also used a internal tilt-sensor that changed the applied force depending on circumstances and actively monitored it.
Renault was to use that one and had already paid for the tooling.
Before i left VCC it was decided that electric handbrake had to wait a year or two pending more studies. (That was my opinion too)
Another issue/question was.. since its marketed as a safety thing it really has to be safe. What happes if the damn car starts to roll anyway.. for example a ferry:
The system pulls the brake cables to a certain tension, but on a ferry that might not be enough. Should the e-brake have a manually controlled maximum tension mode for the ferry event and can we trust the user to remember that?
Ok we probably cannot... what do we do about that?
One idea was to use the new type of ABS sensors that can sense small movements (hall sensor instead of a VR) and let the brake tension the cables if it moves, but they draw current and modern cars have already problems with battery life (current draw) when the car is turned off
End of post (my first one)
RE: Electric Handbrake / Emergency brake - Why?
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
My opinion driving 'stick shift' all my life is that it is horrible. No feel from a button and it feels like it will break at any given time, without notice. Now, in what mode it will break in Im not sure.
Ive also heard of 'a good few' passats giving hell problems with the rear callipers already.
Pat, you mention hill starts, very true, and it is this Im talking about for a feel aspect.
But having said that, I rarely use the handbrake on a hill any way, Instead move my foot swiftly off the brake onto the accelerator , while at the same time bite the clutch, while at the same time give it revs. All that happens in .25 of a second amazingly...
When driving a button handbrake car, that all goes out the window, because on some(cant remember) they will auto apply handbrake if you are on an incline. Now thats annoying if your used of using my method described above.
BG
RE: Electric Handbrake / Emergency brake - Why?
Thanks for your very interesting post - just the sort of insight I was hoping for when I started the thread.
It's also highlighted some interesting "cultural differences" in hand brake use.
Nick
RE: Electric Handbrake / Emergency brake - Why?
A built in hill holder solves another problem.
Another way is for the hand brake to be disengaged by the solenoid or linear motor or whatever while the brake is applied by a spring, like some truck brakes.
I still like a fly off handbrake between the front seats just behind the shift lever and I expect I always will. I still drive for fun at times and convenience or mindless foolproof operation can take a back seat, however I expect I am in a shrinking minority from a marketing point of view.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
If that is your first post, I look forward to many more. Very well done.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
Pneumatic braking systems had or have the ability to stay engaged when the air system went "flat" which is more typical than not.
Once the air system is re-established, the brakes don't just automatically release, it takes some action - full application of air pressure on the brakes for example in the case of one I am thinking of - to release the brakes.
I always wondered what the mechanism inside that cylindrical brake actuator was that accomplished that, but never took one apart to find out because some part or parts of it were spring loaded and loaded with enough force to do bodily harm. My respect for life and limb overcame my natural curiosity. It is one of the few things I never took apart just to see how it ticked.
rmw
RE: Electric Handbrake / Emergency brake - Why?
I am pretty sure it is a coil spring that applies the brakes and air pressure releases them so an air line failure results in a screeching stop rather a runaway truck.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
BG
RE: Electric Handbrake / Emergency brake - Why?
Rod
RE: Electric Handbrake / Emergency brake - Why?
It was bugger to figure out how to get away from initial switch on but every time I braked to a halt, it automatically applied itself. The engine also shut off.
Then when I pressed the accelerator, thee engine started and the ebrake released... this was an automatic (with rear view CCTV for what that's worth since the perceptions in it were completely different to the views in the mirrors).
I really wasn't that keen on either idea. I like to be in control.
With a mechanical handbrake working through the rear brake assembly, you have a very tactile feedback and you can then feel for roll back or forward as you release the footbrake.
You will also know immediately of the cable snaps...and you will get a feel for how well it behaves as any other changes are likely to be progressive.
An electonic brake will either work or not work... so what's the failure mode? fail in position? fail and apply fail and release?
I suspect that the more such features are added, the lazier and less "switched on" the driver becomes ... a recent study reports that drivers using cruise control are significantly more likely to have accidents than drivers without....
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
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.
RE: Electric Handbrake / Emergency brake - Why?
"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
RE: Electric Handbrake / Emergency brake - Why?
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
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
With it on, I can devote all my attention to traffic/road conditions and not worry about the speed.
Rod
RE: Electric Handbrake / Emergency brake - Why?
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
Rod
RE: Electric Handbrake / Emergency brake - Why?
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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RE: Electric Handbrake / Emergency brake - Why?
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://ww
or here:
http://
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
RE: Electric Handbrake / Emergency brake - Why?
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
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
RE: Electric Handbrake / Emergency brake - Why?
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
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
Mike Halloran
Pembroke Pines, FL, USA
RE: Electric Handbrake / Emergency brake - Why?
Thanks Mike.
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
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
www.tynevalleyplastics.co.uk
RE: Electric Handbrake / Emergency brake - Why?
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.
RE: Electric Handbrake / Emergency brake - Why?
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?
RE: Electric Handbrake / Emergency brake - Why?
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
RE: Electric Handbrake / Emergency brake - Why?
Rod
RE: Electric Handbrake / Emergency brake - Why?
Are you referring to the bunch that don't know how to dial a rotary phone?
rmw
RE: Electric Handbrake / Emergency brake - Why?
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
RE: Electric Handbrake / Emergency brake - Why?
This has 6 speed tiptronic automatic transmission.
I couldn't find an emergency/parking brake anywhere. It appears there is a button to press somewhere - I didn't have it long enough to work it out. It wasn't where Audi put their's....
I recall a time, long ago when my master cylinder failed (Mk1 Escort Mexico). So how did I stop? I used the gears and careful application of the handbrake.
What do you do when you have a parking brake... i.e. one of those press to apply and press to release brakes, or you have an electronic controlled brake?
I guess you get on your mobile phone to the police......
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
Rod
RE: Electric Handbrake / Emergency brake - Why?
Perhaps an ejector seat?
But it suggests that what we have with the electronic brake is a parking brake and that we now do not have an emergency brake.
Is that good?
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
If my car was accelerating out of control I certainly would be looking for things to rub up hard against instead of waiting to crash head long into something.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
It would be worth knowing whether these electric/electronic P-brakes can even be applied at any speed, or if they are restricted to use under some nominal speed just to prevent the possible consequences of "unintended rear wheel only brake application".
Norm
RE: Electric Handbrake / Emergency brake - Why?
Without the experience of actually doing the things necessary to pull your arse out of deep do-do, how the heck do you expect results any different than the Lexus crash? I'm a member of the 'spun at high speed' fraternity. BTDT too many times, actually. Brake failure can be mitigated by, as Pat puts it, rubbing up against something. Better...Learn to control the car. Learn what to expect when you pull the wheel over hard at high speed. It's doable, trust me. It might just save your life one day.
Rod
RE: Electric Handbrake / Emergency brake - Why?
Well, you are an engineer, /you/ figure it out. Let's assume, just for laughs, that the people in the industry behave in a more or less rational fashion and don't eat LSD for breakfast.
Incidentally you can't buy a car with a purely electrically linked steering system, they all work even with no electrical power applied. That is an amazingly bad example for your argument, getting rid of the steering column and going all electric would actually be a positive for safety.
Cheers
Greg Locock
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RE: Electric Handbrake / Emergency brake - Why?
rmw
RE: Electric Handbrake / Emergency brake - Why?
Practice can get you into a lot of trouble with the law. Don't ask how I know.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
Every time, the final decision came to "no" for much the same reasons that brakes are not brake by wire --- too risky.
The closest we came in steer by wire is the current electric assist to replace the hydraulic assist.
When you are dealing with millions of units and with potential liability involving them easily $3m per unit failed X failure rate and cost to retrofit / recall, the dynamics of the industry call for innovation in mostly low risk places... or at least.. perceived low risk... like the electronic ignition key.
I am watching carefully how the rear camera system vs. regular mirrors is working out.
My bet - we will not see a mirrorless car in 20 years. There may be only 1 mirror, and it may be tiny, but there will be one.
RE: Electric Handbrake / Emergency brake - Why?
Using the mirror I can move my head side to side to get a wider view. Moving my head side to side to see stuff not in the camera's view made me look like an idiot - and you don't get a joystick to wiggle the camera probably because that would be just one more distraction.
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
This will not only enhance overall rear vision to cover spots not easily covered by mirrors, but will also remove a significant amount of frontal area from a very high ir speed region of the body and will reduce overall width and remove one of the most prone to damage items from the exterior of the car.
As we will no longer need to adjust the mirror to accurately reflect the image to our eyes, the coverage will remain constant to whoever is driving and not require adjustment for each driver or driving position.
Al this with a relative cost saving if the cost of electronics and energy for glass making follows the trends of the last 20 years
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
At what point do the drivers stop thinking?
Should we design cars for idiots or simply keep them off the roads?
PS, you'll need to have an in car camera to allow the ladies to use it to do their make-up and it means having to placew the display where it is convenient to use for that purpose.
OK, that's me red flagged for being sexist. Sorry ladies.
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
JMW
www.ViscoAnalyser.com
RE: Electric Handbrake / Emergency brake - Why?
Rod
RE: Electric Handbrake / Emergency brake - Why?
I forgot what I was going to say
RE: Electric Handbrake / Emergency brake - Why?
That can be done with an LCD that is programmed to display a pic of same person circa 17 or 18, with motion sensors detecting her motions and expressions and replicating it on the screen with a synthesized avatar like likeness.
It will be an incredibly popular option for $15,000 in today's dollars when it is available.
RE: Electric Handbrake / Emergency brake - Why?
An electronic failure in a mirror does not cause a life threatening situation. It is a lot easier step than a steer by wire system from a litigation point of view.
It also eliminates a blind spot where the existing mirrors are mounted.
What did a laptop computer cost 10 or 20 or even 5 years ago.
They where a months salary or more, now they can be less than one days salary.
Regards
Pat
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RE: Electric Handbrake / Emergency brake - Why?
What I'm not sure I agree with is the trend (mandated or otherwise) toward making cars "smarter" in order to compensate for drivers who are dumber or who allow themselves to become more distracted.
I'm more concerned that with electronic everything it becomes possible to develop and produce a vehicle that might inherently be of only marginal stability, with the level of stability required for public consumption provided electronically. It might only require something as simple as an inop ABS wheel sensor to potentially put a driver who has had no opportunity to experience other than linear behavior, in over his head when it all goes offline. Wasn't there a recent Lexus SUV J-turn tipping issue that got solved electronically? 40 years ago, it'd have been the carbon-based brains that got "reflashed" and some useful general human knowledge would have come out of it.
Pat - you have to pick your times and places for keeping your driving practice "current", although you don't have to get deep into "arrest me, officer" territory to keep your skills a step or two ahead of most other drivers.
I rarely use cruise control, as by doing so neither foot can be all that near the pedals that they would need to be near should the traffic situation suddenly deteriorate, and when fumbling around to get on the right side of said pedals could be disastrous. I doubt that I could even stand being essentially a passenger with a steering wheel to hang onto for more than a few minutes at a time, and I suspect that there would be times where I'd be at risk of falling asleep.
Norm