electronic throttle
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From: Grumpy AuContraire on 7 Mar 2010 13:01 bjn wrote: > On Sat, 06 Mar 2010 10:38:19 -0500, Bill Putney <bptn(a)kinez.net> wrote: > >> jim beam wrote: >>> if you buy all this fear-mongering idiocy that electronic throttle is a >>> problem, and that brakes, transmissions and ignition kill switches can >>> all simultaneously fail causing a driver to lose control, it might be >>> worth auto manufacturers of all stripes to adopt a slightly different >>> implementation of electronic throttle [e.t.] - if not for mechanical >>> reasons, but to shut the idiots up... >> The lawyers, politicians, and news media can convince the public of the >> impossible (failure even a totally fail safe system) any time they >> decide to do it depending on political or monetary motivation. IOW - >> the people and companies who do a good job of designing are going to get >> punished anyway (unless they know how to play the game in a corrupt >> system). There are people in our society whose life goal is to make >> sure that that happens. > > > The problem is that now lawyers, politicians and news media are driving (no > pun intended) solution. The way I see them talking, cars will wind up with > a fail-safe throttle that is more fail-safe than the controls of a jumbo > passenger jet. > I'm not sure about this but for sure... The causes you cite certainly contributed in getting to where we're at! Oh, don't forget that little incident when a B-777's engines went to idle about a minute before touch down at Heathrow about a year ago. Aircraft was totaled but there were no major injuries. Cause has been assessed to software/computer glitch. JT
From: Bill Putney on 7 Mar 2010 12:57 jim beam wrote: > On 03/07/2010 08:13 AM, Bill Putney wrote: >> By the second stab, typically brake effectiveness is reduced >> considerably. By third stab - engine overpowers brakes - power assist is >> negligible. No leaks, > > i'll bet you haven't actually tested that. all you know from driving is > that there is sufficient vacuum for the brakes to appear to work ok, > i.e., evacuation rate > leak rate. it's only when leak rate > > evacuation rate that people notice anything. in the mean time, a slow > leak might be sufficient to lose vacuum in 30 seconds or less. Then we disagree. I said this was on multiple cars with no leaks. But in any case, it appears that we agree on more than 3 stabs. Except you still believe that there is sufficient vacuum in the plenum of an engine in gear under acceleration to charge the booster to usable level - and that is simply not correct. >> multiple cars in perfect condition. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
From: Bill Putney on 7 Mar 2010 13:08 Jeff Strickland wrote: > "jim beam" <me(a)privacy.net> wrote in message > news:xbWdnV8Xic4E3Q7WnZ2dnUVZ_rGdnZ2d(a)speakeasy.net... >> On 03/06/2010 08:36 PM, Bill Putney wrote: >>> Jeff Strickland wrote: >>> >>>> ...We have not explored the interaction of traction control and >>>> antilock brakes preventing the brakes from stopping a car with a >>>> throttle intent on being set to the maximum setting. We also have not >>>> looked at the issue of brake fade that comes from the brakes getting >>>> hot. If the brakes locked the front tires, the ABS would sense this >>>> and unlock them. The driver might keep his foot planted firmly on the >>>> brake pedal which has sunk to the floor, but the car still would not >>>> stop. The brakes get hot and fade badly, and the car wouldn't even >>>> slow down... >>> Read my previous post. With throttle applied (even partial throttle), >>> the booster vacuum gets depleted *rapidly*. There is no way to use the >>> brakes to stop a car with an engine of any power at all with throttle >>> applied since, with throttle applied, intake vacuum drops to close to >>> zero. No vacuum = essentially no brakes. Try the experiment I described >>> in my previous post. >>> >> no dude. even with no engine running to replenish vacuum, there is still >> sufficient vacuum reserve in the booster to apply the brakes full-on three >> times. unless you have a leak of course, which could also be affecting >> your experience. >> > > > Doesn't matter. Even if the driver holds the brake pedal, the brakes get hot > and fade, and this will cause them to stop doing the job they are supposed > to do. True - but there are two mechanisms by which the brakes are failing to do their job - loss of vacuum and fading. We could also agree that you can't blame the brakes per-se for "failing" in a situation for which they were not designed, so in that sense they didn't really "fail" (not arguing with you, just making a semantical case there). > The ONLY acceptable condition is that the engine return to idle when the gas > pedal is released. The condition that is REQUIRED, no matter what sort of > linkage -- mechanical or electronic -- is that the engine speed up when the > pedla is pressed, hold steady when the pedal is set to any mid-scale > position, and slow when the pedal is released. Unless these conditions > happen in 100% of the instances, the mechanism is faulty. Period. > > Nobody should ever be exposed to a runaway car, either as a bystander or an > occupant of the car. No argument from me. > We don't know the causes of the runaway Toyotas, but whatever the causes, > they do not appear to be operator induced. And the operators seem to have > been unable to counteract whatever the causes were. Hard to argue with that. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
From: Jeff Strickland on 7 Mar 2010 13:41 "jim beam" <me(a)privacy.net> wrote in message news:XuudnXQZc5NHSw7WnZ2dnUVZ_qydnZ2d(a)speakeasy.net... > On 03/07/2010 08:13 AM, Bill Putney wrote: >> jim beam wrote: >>> On 03/06/2010 08:36 PM, Bill Putney wrote: >>>> Jeff Strickland wrote: >>>> >>>>> ...We have not explored the interaction of traction control and >>>>> antilock brakes preventing the brakes from stopping a car with a >>>>> throttle intent on being set to the maximum setting. We also have not >>>>> looked at the issue of brake fade that comes from the brakes getting >>>>> hot. If the brakes locked the front tires, the ABS would sense this >>>>> and unlock them. The driver might keep his foot planted firmly on the >>>>> brake pedal which has sunk to the floor, but the car still would not >>>>> stop. The brakes get hot and fade badly, and the car wouldn't even >>>>> slow down... >>>> >>>> Read my previous post. With throttle applied (even partial throttle), >>>> the booster vacuum gets depleted *rapidly*. There is no way to use the >>>> brakes to stop a car with an engine of any power at all with throttle >>>> applied since, with throttle applied, intake vacuum drops to close to >>>> zero. No vacuum = essentially no brakes. Try the experiment I described >>>> in my previous post. >>>> >>> >>> no dude. even with no engine running to replenish vacuum, there is >>> still sufficient vacuum reserve in the booster to apply the brakes >>> full-on three times. unless you have a leak of course, which could >>> also be affecting your experience. >>> >> >> By the second stab, typically brake effectiveness is reduced >> considerably. By third stab - engine overpowers brakes - power assist is >> negligible. No leaks, > > i'll bet you haven't actually tested that. all you know from driving is > that there is sufficient vacuum for the brakes to appear to work ok, i.e., > evacuation rate > leak rate. it's only when leak rate > evacuation rate > that people notice anything. in the mean time, a slow leak might be > sufficient to lose vacuum in 30 seconds or less. > I've tested it. Indeed, I've lived it. I had a car that suffered a catastrophic coolant loss at the top of a mountain grade, and my towing coverage was not sufficient to get the car home from there, so I coasted it to the bottom of the hill where the towing coverage would get the car home. The power assist to the brakes lasted exactly three times, after that the brakes were manual and took considerable effort -- I cut my teeth driving a '63 Ford pick-up with manual brakes and owned a Jeep CJ5 with manual brakes, so pressing the brake pedal with the gusto needed to overcome the lack of vacuum assist was not a problem for me. In any case, one gets about 30 seconds of vacuum assist after the engine is off, and then the brakes require considerable pedal pressure to be activated. Having said that, if the engine is running, I see no reason why the vacuum reserve would diminish at all.
From: ED on 7 Mar 2010 13:55
"Bill Putney" <bptn(a)kinez.net> wrote in message news:7vgordFs5kU1(a)mid.individual.net... .... > > Read my previous post. With throttle applied (even partial throttle), the > booster vacuum gets depleted *rapidly*. There is no way to use the brakes > to stop a car with an engine of any power at all with throttle applied > since, with throttle applied, intake vacuum drops to close to zero. No > vacuum = essentially no brakes. Try the experiment I described in my > previous post. > > -- > Bill Putney > (To reply by e-mail, replace the last letter of the alphabet in my address > with the letter 'x') This seems to refute your statement: > http://www.popularmechanics.com/automotive/how_to/4348214.html |