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#1
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![]() "Velvet" wrote in message ... Just zis Guy, you know? wrote: On Sun, 20 Jun 2004 20:08:54 GMT, "Richard J." wrote in message : ... because people driving in a vulnerable vehicle would drive more safely? That idea didn't seem to work before seat belts were invented, when occupants used to die by being ejected through the windscreen. Indeed it still happens. On the other hand, they drive less carefully when protected by airbags, abs and seatbelts. Guy Not all of them do, ta :-) I don't rely on ABS to stop me quicker - I use it to even out the fact that the car in front probably has it and will stop quicker than I can if I don't have it... so my driving hasn't snipped Bit of a myth that ABS enables a vehicle to stop quicker, in fact it can have the opposite effect. It's purpose is to enable the vehicle to be steered while braking hard, which without ABS often results in a skid and loss of control. |
#2
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Orienteer wrote:
"Velvet" wrote in message ... Just zis Guy, you know? wrote: On Sun, 20 Jun 2004 20:08:54 GMT, "Richard J." wrote in message : ... because people driving in a vulnerable vehicle would drive more safely? That idea didn't seem to work before seat belts were invented, when occupants used to die by being ejected through the windscreen. Indeed it still happens. On the other hand, they drive less carefully when protected by airbags, abs and seatbelts. Guy Not all of them do, ta :-) I don't rely on ABS to stop me quicker - I use it to even out the fact that the car in front probably has it and will stop quicker than I can if I don't have it... so my driving hasn't snipped Bit of a myth that ABS enables a vehicle to stop quicker, in fact it can have the opposite effect. It's purpose is to enable the vehicle to be steered while braking hard, which without ABS often results in a skid and loss of control. However, in the situation where the vehicle in front has ABS, and will brake it to the maximum without inducing a skid (skidding leads to longer stopping times?) it means that the following vehicle has to be able to control their braking to the same fine degree to avoid starting the skid, and many will either be too cautious or overcook and skid... So in my experience (and I do speak from experience) when you avoid a skid in a non-abs car and the one in front does have it, you end up braking slower, with obvious consequences if you're close enough... -- Velvet |
#3
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Velvet wrote:
So in my experience (and I do speak from experience) when you avoid a skid in a non-abs car and the one in front does have it, you end up braking slower, with obvious consequences if you're close enough... You mean "too close". -- Mark. |
#4
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Mark Tranchant wrote:
Velvet wrote: So in my experience (and I do speak from experience) when you avoid a skid in a non-abs car and the one in front does have it, you end up braking slower, with obvious consequences if you're close enough... You mean "too close". Indeed ;-) -- Velvet |
#5
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On Mon, 21 Jun 2004 07:08:11 GMT, "Orienteer"
wrote (more or less): .... Bit of a myth that ABS enables a vehicle to stop quicker, in fact it can have the opposite effect. Only on loose surfaces like snow or gravel. On clean dry surfaces a car with independent ABS per wheel can stop faster than a non-abs car (which will likely skid under extreme braking), and gains the controllability advantage of cadence-braking without having to stop braking all four wheels, which a non-abs car has to do to effect cadence braking. It's purpose is to enable the vehicle to be steered while braking hard, which without ABS often results in a skid and loss of control. A skid also results in longer braking distances. -- Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk |
#6
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On Mon, 21 Jun 2004 07:08:11 GMT,
Orienteer wrote: Bit of a myth that ABS enables a vehicle to stop quicker, in fact it can have the opposite effect. It's purpose is to enable the vehicle to be steered while braking hard, which without ABS often results in a skid and loss of control. I don't have any figures for it but I suspect that when braking hard from high speeds (70mph+) ABS may well enable a car to stop quicker. Some (10+?) years ago there was an artical in SciAm about emergency stops in cars at motorway speeds and it was suggested that the best bet for the cars of the time might well be to deliberately skid. IIRC stopping distances from these sorts of speeds when skidding were about 20% further than the perfect stop. However, without ABS the braking is split in a fixed percentage between back and front wheels. The weight transfer to the front wheels can cause the rear wheels to lock putting the car into a spin. By deliberately locking all the wheels the car will stay pretty much in a straight line (motorways don't tend to have enough camber to be likely to put a skidding car into a spin.) ABS eliminates this problem and allows maximum braking on the front wheels. But ABS doesn't have to be a good thing. The one time I have skidded on the motorway I was very grateful for the noise. Picture the scene - me on empty motorway, slip lane joining. Slow lorry almost at end of slip lane that would be joining shortly after I had passed. Another car on sliplane that would be joining about the same time as the lorry. So I moved from lane 1 to lane 3 in order to give both vehicles joining room to join without having to adjust their speeds. But the car doesn't move into lane 2 to pass the lorry but continues into lane 3. Now I should have anticipated this but by the time I realised he wasn't going to stay in lane 2 I was about level with his rear door and going maybe 10mph faster. I didn't have time for the horn but my squealing tyres meant he only came about 2 feet into lane 3. (Skidding from 70mph to about 45mph leaves a big cloud of smoke!) Tim. -- God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light. http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/ |
#7
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On Mon, 21 Jun 2004 19:59:49 +0000 (UTC), Tim Woodall
wrote in message : I don't have any figures for it but I suspect that when braking hard from high speeds (70mph+) ABS may well enable a car to stop quicker. I have only ever once managed to skid a car at 70, and that was a BX with no ABS where the same hydraulics work the brakes and the suspension. Weight transfer makes it quite hard to skid a car at 70. Guy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University |
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