electronic throttle
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From: clare on 7 Mar 2010 17:53 On Sun, 7 Mar 2010 09:45:14 -0800, "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote: > >"Ed Pawlowski" <esp(a)snetnospam.net> wrote in message >news:GfedncnS4KVktg7WnZ2dnUVZ_s2dnZ2d(a)giganews.com... >> >> >> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote >>> Brake interlocks are a relatively new thing. I drove cars for 30 years >>> before I had one with a brake pedal interlock. Your elderly customer also >>> drove for a very long time with cars that had no brake interlock, and he >>> wasn't aware that his new car had one. My guess is that he wasn't aware >>> that any car had one ... >> >> True >> >>> >>> There is no inherent accident waiting to happen without the brake >>> interlock. >> >> Elderly person, foot on gas, put car in gear. Crash Happens too >> frequently. >> >> > >We had cars built for almost 90 years before brake interlocks came around. >The occurance of a car shifting out of P was relatively rare, and almost >always involved children playing in the car and moving the gear selector >while the engine was not even ON. > >Yes, a person could take the car out of P while the engine was running, but >as a practical matter, this almost never happened. Almost never. EXCEPT - it took the situation where Ford transmissions could sometimes jump out of park (due to a defect in the park mechanism or linkage) for the industry to be MANDATED to provide a brake/shift interlock > > > > >> >>> Brake interlocks were put in to prevent children from moving the car from >>> P and allowing it to roll down the driveway, they were not put in to keep >>> the driver from being an idiot. >> >> Perhaps, but the side effects are good. > >Absolutely, but the purpose was the children playing in the car, not the >inattentive driver. The gear selector has gates that are there for the >driver to make him press a button or move the lever sideways to get out of >P. A child playing in the car can press the button or move the lever >sideways while the vehicle was parked, this is the condition for which the >brake interlock was created. > > > >
From: clare on 7 Mar 2010 17:56 On Sun, 7 Mar 2010 10:41:23 -0800, "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote: > >"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. > > If the engine is running at IDLE or no load, you are correct. On Decell going down hill, you have vacuum like gangbusters. NONE while under any more than very light load. > > >
From: clare on 7 Mar 2010 18:03 On Sun, 7 Mar 2010 11:10:20 -0800, "theref" <theref(a)seanet.com> wrote: > > >"Grumpy AuContraire" <GrumpyOne(a)GrumpyvilleNOT.com> wrote in message >news:99adnZJAetdSdQ7WnZ2dnUVZ_qidnZ2d(a)giganews.com... >> 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 > >I believe that was traced to icing in the fuel system. SOP now is to cycle >fuel after prolonged low temp at altitude. Icing on a JET????????? Don't think so.
From: News on 7 Mar 2010 18:05 clare(a)snyder.on.ca wrote: > On Sun, 7 Mar 2010 11:10:20 -0800, "theref" <theref(a)seanet.com> wrote: > >> >> "Grumpy AuContraire" <GrumpyOne(a)GrumpyvilleNOT.com> wrote in message >> news:99adnZJAetdSdQ7WnZ2dnUVZ_qidnZ2d(a)giganews.com... >>> 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 >> I believe that was traced to icing in the fuel system. SOP now is to cycle >> fuel after prolonged low temp at altitude. > Icing on a JET????????? > Don't think so. Absolutely. Determined to be cause of BA 777 landing short at Heathrow.
From: Bill Putney on 7 Mar 2010 18:09
clare(a)snyder.on.ca wrote: > Sorry Jim - but you are wrong. > A diesel engined vehicle with a mechanical vacuum pump would work as > you envision - but under any substantial load there is not enough > manifold vacuum produced to provide full braking assist. With both > feet on the brake pedal a strong man MAY be able to provide enough > brake line pressure to stop the car at half throttle. Kind of related: In the early 80's (of the last century), when cam design rules were changing (I think to provide overlap, etc. for emissions - not 100% sure if that was the exact reason, but I think so), vacuum levels dropped on engines. Before other methods were figured out to compensate for that (I'm guessing just building the boosters larger and futzing with the design of the master cylinders and calipers so the assist worked well on generally lower vacuum), GM had to install electrically driven vacuum pumps in the fenders of some of their cars to provide sufficient booster vacuum. I found out about that after I installed a "recreation" cam on a 1980 Chev. Citation after its factory cam wore out. After installing the new cam, the brakes had insufficient assist because the cam design dropped the vacuum levels. I researched it and found out about the electric vacuum pumps and went to a junk yard and grabbed one and installed it (I think from a Pontiac J2000, J4000, or J6000 - something like that) - anyway, it worked *great*. In my research at the time, people also told me that electric vacuum pumps and/or extra vacuum reservoirs were often used on race cars for the same reason (hi-perf. cams and low vacuum during acceleration). -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') |