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Not strictly true. ABS can operate in this manner but strictly speaking the speed sensor is there to detect the rotationary speed of the wheel falling below a predified point and thus releasing the brake on that wheel (the reverse is in effect for HDC). This may be 40kph, 4kph or 0kph depending on how the system is configured. In fact the SLABS ECU cannot detect speeds lower than about 2kph.Quote:
Originally Posted by duff
Even if it doesn't have a great bearing on safety - it certainly helps with the predictability of the car.
Having said that i would prefer a vehicle without ABS for offroad as I know I can control it.
Cheers
Dave.
I had to do an emergency stop once in an F250 with ABS on a gravel road. I swear it picked up speed once the ABS kicked in. Luckily the cow got out of my way as I didn't stop before where the cow was.
That is a 2004 F250 so not old technology (well it probably is being an American tank).
RE: installing an on/off switch after the fuse box...
For those who have mentioned that this would be the best way to turn off the ABS I have another question: Would doing this alter the braking capacity of the vehicle, I mean the brakes work properly when ABS isn't working right? Could there be a problem with the flow of brake fluid bypassing the system or something? Any ideas as to how "exactly" the system works?
I guess the ABS warning light would come on.
chosen
and drum brakes are more efficient than discs;)
but they lack the ability to dissipate heat as well a disc can leading to brake fade when pushed hard.
Of course, you could always just drive at a speed appropriate for the road conditions.....;)
Yes of course the technical functioning of ABS is as you describe.
I was talking in Laymens terms and describing what is often the net result on the road. It is really quite dangerous on the dirt(I am not talking about normal hard braking,, but an all out do or die emergency stop.) ABS is Dangerous/less effective than non ABS brakes on loose surface. I dont think it is practicable to travel at 60kmh when you are travelling long distances on the dirt regularly,, 100kmh is safe on maintained dirt roads, except for when you need to rely on ABS to stop quickly:eek:. so the option of turning off ,, or better still having a "loose surface" switch, would result in a more useable vehicle for me.
But each to their own I guess
Quote:
Originally Posted by dm_td5
Skidding wheels will pull you up heaps quicker on gravel,they dig in and bite.
I disable my TC/ABS on the gravel when towing my firewood,I cant stop it with the ABS.Did a few practice runs on/off.My 450kg UNBRAKED tandem trailer with 2 tonnes of wood on board takes some stopping in the gravel,it stops in less than half the distance at 60ks with the ABS OFF.
YES I KNOW ITS SEVERELY OVERLOADED,yes Im STUPID,but I will be building a trailer with electric brakes to replace this trailer,could rush out and buy one but want to build my own,have purchased the steel for the chassis/cage.
Andrew
This one comes around about once a year on one site or another and the same arguments appear but cartm58 is the closest to what you should do when driving on gravel surfaces.
The correct way, and this takes HEAPS of practising to achieve, is to NOT slam the brakes on.
I have practised and practised and the best I can do when an unexpected emergence brake in needed on a gravel road is to instinctively jump on the breaks but as soon as the grey matter kicks in I back the break pedal pressure off a bit and the vehicle will then pull up pretty quickly.
It’s still not as quick as a non ABS equipped vehicle but there is one major difference and it doesn’t matter if you stand on the brakes or control the braking, ABS gives you the ability to control the vehicle while locking up the brakes usually means you either loose control or you have to release the brakes to get back steering control.
You are far better off having the ability to maybe able to steer around an obstacle at some speed that skid into it at a lower speed.
Next time you are on a wide, straight section of gravel road, take the ABS fuse out, get up to 60 and slam the brakes on and don’t take your foot off till you have stopped.
Go back, put the fuse back and do it again.
On average, depending on the surface, ABS will take about 1/3 greater distance but compere the stopping patens. The ABS will be longer but no matter what happened during the braking, you can keep it straight, while the non ABS paten will be anything but straight.
The best thing you can do with an ABS vehicle on gravel is to learn to drive with the advantages and disadvantages of it and in the long run the advantages far out weigh the disadvantages.
ABS vehicles, even on gravel, gives inexperienced drivers a far better chance of surviving an emergence braking situation.
Cheers.
Driving on dirt roads needs constant awareness and you should keep the speed down and never assume a maximum safe speed. Conditions can change quickly, oncoming galah's speeding blindly towards you in the middle of the track, loose surfaces etc can all bring things to a catastrophic end. 100kph isn't essentially safe on dirt tracks anymore than 20kph is. You must always drive defensively and monitor the conditions, the faster you go, the more hazardous it can be. And, yes, I drive a lot of dirt tracks and in case you haven't guessed people who speed (regardless of the conditions) and/or drive offensively on dirt tracks really annoy meQuote:
Originally Posted by duff
:soapbox:
On a lighter note, here's some alternative meanings for the abbreviation of Antiblockiersystem (correct meaning of the Wabco ABS): http://acronyms.thefreedictionary.co...d+brake+system)