ABS brakes
in [Drive]
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From: Nick Naim on 1 May 2010 16:32 "Dave__67" <spamTHISbrp(a)yahoo.com> wrote in message news:480b6c61-98f6-4e29-8814-e8f7c5aaf02a(a)q15g2000yqj.googlegroups.com... On Apr 21, 11:55 pm, "Nick Naim" <orb...(a)ix.netcom.com> wrote: > I pegged her at 70 years old plus minus. > She pulled out of a fast food on my left in a heart beat > I,m in the left lane of thru traffic. > I,m on the binders on ABS and they are working on overtime. > I come to a stop 3 feet from her right front fender. If your ABS is kicking on on dry clean pavement you need better tires- you're throwing away stopping distance! Working not kicking........tires are ok. Would have hit her in right front fender without ABS. Traffic was on my right side so no evasive to my right. Dave
From: Ashton Crusher on 3 May 2010 22:22 On Wed, 28 Apr 2010 04:39:25 -0700 (PDT), Dave__67 <spamTHISbrp(a)yahoo.com> wrote: >On Apr 27, 1:37�pm, Alan Baker <alangba...(a)telus.net> wrote: >> In article >> <e00930b2-999a-4467-adec-85b62b909...(a)v14g2000yqb.googlegroups.com>, >> >> >> >> �Dave__67 <spamTHIS...(a)yahoo.com> wrote: >> > On Apr 26, 2:41�pm, Alan Baker <alangba...(a)telus.net> wrote: >> > > In article >> > > <9bd36917-1c4c-48ba-bb9b-7061a9d6a...(a)z7g2000yqb.googlegroups.com>, >> >> > > �Dave__67 <spamTHIS...(a)yahoo.com> wrote: >> > > > On Apr 22, 9:04�pm, Ashton Crusher <d...(a)moore.net> wrote: >> > > > > On Thu, 22 Apr 2010 05:08:07 -0700 (PDT), Dave__67 >> >> > > > > <spamTHIS...(a)yahoo.com> wrote: >> > > > > >On Apr 21, 11:55�pm, "Nick Naim" <orb...(a)ix.netcom.com> wrote: >> > > > > >> I pegged her at 70 years old plus minus. >> > > > > >> She pulled �out of a fast food on my left in a heart beat >> > > > > >> I,m in the left lane of thru traffic. >> > > > > >> I,m on the binders on ABS and they are working on overtime. >> > > > > >> I come to a stop 3 feet from her right front fender. >> >> > > > > >If your ABS is kicking on on dry clean pavement you need better tires- >> > > > > >you're throwing away stopping distance! >> >> > > > > >Dave >> >> > > > > How do y9ou figure that? �ABS works, wet or dry, to maximize the >> > > > > amount of time the tire is at or near peak friction level. � >> >> > > > No, it does not. >> >> > > > ABS is designed to allow you to still steer while mindlessly whomping >> > > > on the brakes. To do so it has to leave a little traction on the >> > > > plate. >> >> > > Again, not quite. ABS will reduce the amount of force applied to the >> > > brakes whenever conditions result in the tire starting to lock up. >> >> > > One of those conditions could be a change in the friction of the >> > > surface, but one could also be that you've turned the wheel. >> >> > > So there is no traction "left on the plate" in the way you meant. >> >> > > > Anyway, on dry pavement, if you can lock up the brakes, your brakes >> > > > are better than your tires. If you improve the grip of the tires >> > > > you'll stop faster. >> >> > > Not just on dry pavement. :-) >> >> > > -- >> > > Alan Baker >> > > Vancouver, British Columbia >> > > <http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg> >> >> > If the algorithms and sensors were perfect, and there were no control >> > loop delay, sure. >> >> Sorry, but they don't have to be perfect. Just better than human. And >> give the speed of human reactions, that's not that hard. >> >> -- >> Alan Baker >> Vancouver, British Columbia >> <http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg> > >I'm stating clearly that ABS leaves some traction 'on the plate' >unused. The fact that an expert using skilled braking technique on dry >pavement can stop faster with the ABS off proves this >incontrovertibly. > >I'm not debating improvements ABS gives in most circumstances compared >to human brake modulation > > >Dave. > > Please post your reference to this statistically valid test that shows that over a meaningful range of friction values an expert can consistently beat an excellent ABS.
From: Ashton Crusher on 4 May 2010 00:32 On Wed, 28 Apr 2010 18:01:52 -0500, russotto(a)grace.speakeasy.net (Matthew Russotto) wrote: >In article <bbeft5hfniv2tfhknmpm1oh71jpbp3m65n(a)4ax.com>, >Ashton Crusher <demi(a)moore.net> wrote: >> >>I'm not too keen on the idea of "effective" being that when the >>pavement is wet is to go sliding out of control. > >If you lock up all four wheels, the car does not go "sliding out of >control". It behaves in a quite predictable manner, sliding >straight in the direction it was going when the wheels locked up if on >a flat surface. If by predictable you mean your ONLY choice is to *hope* you don't hit whatever winds up in front of you since you have no control over your trajectory then sure. If by predictable you mean that you know you'll be aimed somewhere but you don't know if it will be aimed forward, 45 degrees, sideways, or backwards, or god knows which way, then yeah, it's real predictable. Some of us don't consider that to be "in control" of a vehicle. If your eyes were closed and a bag was over your head in that situation you'd have exactly the same level of "control" you deem adequate.
From: Ashton Crusher on 4 May 2010 00:36 On Wed, 28 Apr 2010 19:12:05 -0500, russotto(a)grace.speakeasy.net (Matthew Russotto) wrote: >In article <slrnhthhs7.er2.aznomad.3(a)ip70-176-155-130.ph.ph.cox.net>, >AZ Nomad <aznomad.3(a)PremoveOBthisOX.COM> wrote: >> >>I have too. You're not driving; merely a passenger when you're >>sliding like that. You also run the risk of turning sideways, >>backwards, or rolling the vehicle if you encounter sudden friction >>while turned sideways. > >You're not a passenger when sliding with all four wheels locked; >you've reached the limits of your control and will have to back off >the brakes if you want to do anything else, but you're not out of >control. You are on low friction wet pavement. >You're not going to turn sideways If there is lateral differential friction, which occurs often enough it can be an issue, you will spin anywhere from 10's of degrees to 360+ degrees, all the while going "straight" ahead. unless there's a major >irregularity in the road surface, or you were spinning already. And >unless you drive an SUV or other high center of gravity vehicle, an >untripped rollover is extremely unlikely even if you do spin. 1 out of 3
From: Ashton Crusher on 4 May 2010 00:43
On Wed, 28 Apr 2010 18:05:38 -0500, russotto(a)grace.speakeasy.net (Matthew Russotto) wrote: >In article <nreft51k6vg3gluv877sfni2jbkbsgupeh(a)4ax.com>, >Ashton Crusher <demi(a)moore.net> wrote: >>On Tue, 27 Apr 2010 21:38:43 -0500, russotto(a)grace.speakeasy.net >>(Matthew Russotto) wrote: >> >>>In article <57q9t5lr4jhb5hervqhb2q51b3poff1eig(a)4ax.com>, >>>Ashton Crusher <demi(a)moore.net> wrote: >>>>>No. ABS is very close to threshold braking, but it is not. It is a very >>>>>rapid sequence of going slightly beyond the threshold and then back to >>>>>less than the threshold. >>>> >>>>Where you are getting that definition from? It makes no sense to me >>>>and is contrary to what people have claimed in the past. What's your >>>>definition of the "threshold" point? >>> >>>Take a chart of brake pressure (at the caliper or shoe) versus braking >>>force applied to the road by that tire. It'll look basically like a >>>line going from 0 upwards fairly linearly, leveling off slightly as it nears a >>>peak, followed by a sharp dropoff to a horizontal line. Perfect >>>threshold braking would be holding braking pressure right at that >>>peak. >> >>You've just described what ABS does in any practical sense. To say ABS >>is qualitatively different then threshold braking is just splitting >>hairs. > >No, ABS does not do that. ABS works by releasing pressure until the >wheels are no longer approaching lock, then re-applying until they >are, then releasing, etc. An ideal ABS would approach the same >effect as threshold braking, but the real ABS control loop is long and sloppy >enough that the difference is noticable. Are you think threshold braking by a human is different how??? Are you suggesting that TBbH never releases pressure? |