Order Jeep -> Lose Rebate??
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
Roughly 12/9/03 20:06, Mike Romain's monkeys randomly typed:
> Geese guys, all the studies and the makers of the damn things say they
> take longer to stop than manual brakes in a straight line stop like one
> sees in traffic. Period!
>
> They sacrifice some stopping distance for extra control.
>
> Simple concept. Makes total sense to me.
>
Except that it is a misstatement of fact and a contradiction
of the SAE test results except on wedgeable surfaces. And worse
ignores the fact that the extra control itself contributes to
the fatalities.
Other than that I guess it could make sense if you'd actually
take the time to read the SAE tests where ABS does indeed stop
faster most of the time and where they also figure out why
the typical driver with ABS doesn't. Something ABS by itself
can't cure.
--
Fan of the dumbest team in America.
> Geese guys, all the studies and the makers of the damn things say they
> take longer to stop than manual brakes in a straight line stop like one
> sees in traffic. Period!
>
> They sacrifice some stopping distance for extra control.
>
> Simple concept. Makes total sense to me.
>
Except that it is a misstatement of fact and a contradiction
of the SAE test results except on wedgeable surfaces. And worse
ignores the fact that the extra control itself contributes to
the fatalities.
Other than that I guess it could make sense if you'd actually
take the time to read the SAE tests where ABS does indeed stop
faster most of the time and where they also figure out why
the typical driver with ABS doesn't. Something ABS by itself
can't cure.
--
Fan of the dumbest team in America.
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
On 09 Dec 2003 07:17 PM, Lon Stowell posted the following:
> If the computer is purely ABS, that may be true for you, but
> it has been proven to be not true for everybody. Particularly
> in off-road situations where even a lockwheel stop is faster
> than an ABS one--with today's control systems for ABS. And
> on some slippery surfaces, racing drivers can beat ABS sometimes.
I will never have the ability to modulate the pressure applied to the
calipers and wheel cylinders individually like the ABS system can. Also,
I may do pretty good on a good day, but I may not be having a good day.
The computer has the same day, every day. On my previous rig, when the
ABS computer was having a bad day, it reverted to standard brakes and
the warning light came on advising me of this.
One thing which I read once but haven't taken the time to confirm, is
that ABS is banned in formula one racing because it allows mediocre
drivers to be competitive with the better drivers.
> As for training, lecture style training even with visual aids
> and movies has demonstrated no improvement in driver use of ABS.
> They still do it wrong. Which may be why it is impossible to
> get a racing license without instructor observed track time
> where you bend the shiny parts until you figure out how not to.
Well, that is the problem with lecture style training. It needs to be
followed by practical training. I personally have practiced on deserted
roads and parking lots to get a feel for how the ABS reacts when I am
not in danger of hitting something. My reaction to the ABS isn't yet as
fast as my reaction to a skid (guess which I spend more time practicing,
heheheh), but I don't have to think about it either, I recognize the hum
and mash the pedal.
Just because the training used is not effective, doesn't invalidate the
concept of getting training. Another thing which I do and recommend, is
occasionally TEST the ABS to make sure it is actually still working
before it is needed.
> Seems the biggest contribution to ABS accidents is that the ABS
> allows the driver's insanely suicidal steering inputs to actually
> have effect, whereas the same driver without ABS will usually
> have the front wheels skidding enough that steering input
> has far lower effect.
Once again, that is an issue that could be solved through effective
training. Probably never will, but it is hardly the fault of the
mechanical device in question.
> Plus the drivers refuse to trust the
> ABS and keep it engaged. Braking time for ABS enabled is
> often slightly less than for disabled.
I always say that if you can't make the leap of trusting the system,
that you are better off without ABS. What I find particularly dangerous,
is switching between rigs that have it and those that don't. That is
one of the reasons that my one wheel drive pickup is parked until spring,
in addition to the fact that it is a slug in the winter and lacks the
traction to get out of its own way.
> Which is why some vehicles have added yaw and slew rate controls
> on top of ABS... drivers with none of the mandatory "body learning"
> type experience it takes to learn how to use ABS...or not use it.
Eventually they will probably invent a vehicle which will totally take
driving ability out of the equation. I'm only in favor of that if they
will still let me drive my old stuff on the road.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
> If the computer is purely ABS, that may be true for you, but
> it has been proven to be not true for everybody. Particularly
> in off-road situations where even a lockwheel stop is faster
> than an ABS one--with today's control systems for ABS. And
> on some slippery surfaces, racing drivers can beat ABS sometimes.
I will never have the ability to modulate the pressure applied to the
calipers and wheel cylinders individually like the ABS system can. Also,
I may do pretty good on a good day, but I may not be having a good day.
The computer has the same day, every day. On my previous rig, when the
ABS computer was having a bad day, it reverted to standard brakes and
the warning light came on advising me of this.
One thing which I read once but haven't taken the time to confirm, is
that ABS is banned in formula one racing because it allows mediocre
drivers to be competitive with the better drivers.
> As for training, lecture style training even with visual aids
> and movies has demonstrated no improvement in driver use of ABS.
> They still do it wrong. Which may be why it is impossible to
> get a racing license without instructor observed track time
> where you bend the shiny parts until you figure out how not to.
Well, that is the problem with lecture style training. It needs to be
followed by practical training. I personally have practiced on deserted
roads and parking lots to get a feel for how the ABS reacts when I am
not in danger of hitting something. My reaction to the ABS isn't yet as
fast as my reaction to a skid (guess which I spend more time practicing,
heheheh), but I don't have to think about it either, I recognize the hum
and mash the pedal.
Just because the training used is not effective, doesn't invalidate the
concept of getting training. Another thing which I do and recommend, is
occasionally TEST the ABS to make sure it is actually still working
before it is needed.
> Seems the biggest contribution to ABS accidents is that the ABS
> allows the driver's insanely suicidal steering inputs to actually
> have effect, whereas the same driver without ABS will usually
> have the front wheels skidding enough that steering input
> has far lower effect.
Once again, that is an issue that could be solved through effective
training. Probably never will, but it is hardly the fault of the
mechanical device in question.
> Plus the drivers refuse to trust the
> ABS and keep it engaged. Braking time for ABS enabled is
> often slightly less than for disabled.
I always say that if you can't make the leap of trusting the system,
that you are better off without ABS. What I find particularly dangerous,
is switching between rigs that have it and those that don't. That is
one of the reasons that my one wheel drive pickup is parked until spring,
in addition to the fact that it is a slug in the winter and lacks the
traction to get out of its own way.
> Which is why some vehicles have added yaw and slew rate controls
> on top of ABS... drivers with none of the mandatory "body learning"
> type experience it takes to learn how to use ABS...or not use it.
Eventually they will probably invent a vehicle which will totally take
driving ability out of the equation. I'm only in favor of that if they
will still let me drive my old stuff on the road.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
On 09 Dec 2003 07:17 PM, Lon Stowell posted the following:
> If the computer is purely ABS, that may be true for you, but
> it has been proven to be not true for everybody. Particularly
> in off-road situations where even a lockwheel stop is faster
> than an ABS one--with today's control systems for ABS. And
> on some slippery surfaces, racing drivers can beat ABS sometimes.
I will never have the ability to modulate the pressure applied to the
calipers and wheel cylinders individually like the ABS system can. Also,
I may do pretty good on a good day, but I may not be having a good day.
The computer has the same day, every day. On my previous rig, when the
ABS computer was having a bad day, it reverted to standard brakes and
the warning light came on advising me of this.
One thing which I read once but haven't taken the time to confirm, is
that ABS is banned in formula one racing because it allows mediocre
drivers to be competitive with the better drivers.
> As for training, lecture style training even with visual aids
> and movies has demonstrated no improvement in driver use of ABS.
> They still do it wrong. Which may be why it is impossible to
> get a racing license without instructor observed track time
> where you bend the shiny parts until you figure out how not to.
Well, that is the problem with lecture style training. It needs to be
followed by practical training. I personally have practiced on deserted
roads and parking lots to get a feel for how the ABS reacts when I am
not in danger of hitting something. My reaction to the ABS isn't yet as
fast as my reaction to a skid (guess which I spend more time practicing,
heheheh), but I don't have to think about it either, I recognize the hum
and mash the pedal.
Just because the training used is not effective, doesn't invalidate the
concept of getting training. Another thing which I do and recommend, is
occasionally TEST the ABS to make sure it is actually still working
before it is needed.
> Seems the biggest contribution to ABS accidents is that the ABS
> allows the driver's insanely suicidal steering inputs to actually
> have effect, whereas the same driver without ABS will usually
> have the front wheels skidding enough that steering input
> has far lower effect.
Once again, that is an issue that could be solved through effective
training. Probably never will, but it is hardly the fault of the
mechanical device in question.
> Plus the drivers refuse to trust the
> ABS and keep it engaged. Braking time for ABS enabled is
> often slightly less than for disabled.
I always say that if you can't make the leap of trusting the system,
that you are better off without ABS. What I find particularly dangerous,
is switching between rigs that have it and those that don't. That is
one of the reasons that my one wheel drive pickup is parked until spring,
in addition to the fact that it is a slug in the winter and lacks the
traction to get out of its own way.
> Which is why some vehicles have added yaw and slew rate controls
> on top of ABS... drivers with none of the mandatory "body learning"
> type experience it takes to learn how to use ABS...or not use it.
Eventually they will probably invent a vehicle which will totally take
driving ability out of the equation. I'm only in favor of that if they
will still let me drive my old stuff on the road.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
> If the computer is purely ABS, that may be true for you, but
> it has been proven to be not true for everybody. Particularly
> in off-road situations where even a lockwheel stop is faster
> than an ABS one--with today's control systems for ABS. And
> on some slippery surfaces, racing drivers can beat ABS sometimes.
I will never have the ability to modulate the pressure applied to the
calipers and wheel cylinders individually like the ABS system can. Also,
I may do pretty good on a good day, but I may not be having a good day.
The computer has the same day, every day. On my previous rig, when the
ABS computer was having a bad day, it reverted to standard brakes and
the warning light came on advising me of this.
One thing which I read once but haven't taken the time to confirm, is
that ABS is banned in formula one racing because it allows mediocre
drivers to be competitive with the better drivers.
> As for training, lecture style training even with visual aids
> and movies has demonstrated no improvement in driver use of ABS.
> They still do it wrong. Which may be why it is impossible to
> get a racing license without instructor observed track time
> where you bend the shiny parts until you figure out how not to.
Well, that is the problem with lecture style training. It needs to be
followed by practical training. I personally have practiced on deserted
roads and parking lots to get a feel for how the ABS reacts when I am
not in danger of hitting something. My reaction to the ABS isn't yet as
fast as my reaction to a skid (guess which I spend more time practicing,
heheheh), but I don't have to think about it either, I recognize the hum
and mash the pedal.
Just because the training used is not effective, doesn't invalidate the
concept of getting training. Another thing which I do and recommend, is
occasionally TEST the ABS to make sure it is actually still working
before it is needed.
> Seems the biggest contribution to ABS accidents is that the ABS
> allows the driver's insanely suicidal steering inputs to actually
> have effect, whereas the same driver without ABS will usually
> have the front wheels skidding enough that steering input
> has far lower effect.
Once again, that is an issue that could be solved through effective
training. Probably never will, but it is hardly the fault of the
mechanical device in question.
> Plus the drivers refuse to trust the
> ABS and keep it engaged. Braking time for ABS enabled is
> often slightly less than for disabled.
I always say that if you can't make the leap of trusting the system,
that you are better off without ABS. What I find particularly dangerous,
is switching between rigs that have it and those that don't. That is
one of the reasons that my one wheel drive pickup is parked until spring,
in addition to the fact that it is a slug in the winter and lacks the
traction to get out of its own way.
> Which is why some vehicles have added yaw and slew rate controls
> on top of ABS... drivers with none of the mandatory "body learning"
> type experience it takes to learn how to use ABS...or not use it.
Eventually they will probably invent a vehicle which will totally take
driving ability out of the equation. I'm only in favor of that if they
will still let me drive my old stuff on the road.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
On 09 Dec 2003 07:17 PM, Lon Stowell posted the following:
> If the computer is purely ABS, that may be true for you, but
> it has been proven to be not true for everybody. Particularly
> in off-road situations where even a lockwheel stop is faster
> than an ABS one--with today's control systems for ABS. And
> on some slippery surfaces, racing drivers can beat ABS sometimes.
I will never have the ability to modulate the pressure applied to the
calipers and wheel cylinders individually like the ABS system can. Also,
I may do pretty good on a good day, but I may not be having a good day.
The computer has the same day, every day. On my previous rig, when the
ABS computer was having a bad day, it reverted to standard brakes and
the warning light came on advising me of this.
One thing which I read once but haven't taken the time to confirm, is
that ABS is banned in formula one racing because it allows mediocre
drivers to be competitive with the better drivers.
> As for training, lecture style training even with visual aids
> and movies has demonstrated no improvement in driver use of ABS.
> They still do it wrong. Which may be why it is impossible to
> get a racing license without instructor observed track time
> where you bend the shiny parts until you figure out how not to.
Well, that is the problem with lecture style training. It needs to be
followed by practical training. I personally have practiced on deserted
roads and parking lots to get a feel for how the ABS reacts when I am
not in danger of hitting something. My reaction to the ABS isn't yet as
fast as my reaction to a skid (guess which I spend more time practicing,
heheheh), but I don't have to think about it either, I recognize the hum
and mash the pedal.
Just because the training used is not effective, doesn't invalidate the
concept of getting training. Another thing which I do and recommend, is
occasionally TEST the ABS to make sure it is actually still working
before it is needed.
> Seems the biggest contribution to ABS accidents is that the ABS
> allows the driver's insanely suicidal steering inputs to actually
> have effect, whereas the same driver without ABS will usually
> have the front wheels skidding enough that steering input
> has far lower effect.
Once again, that is an issue that could be solved through effective
training. Probably never will, but it is hardly the fault of the
mechanical device in question.
> Plus the drivers refuse to trust the
> ABS and keep it engaged. Braking time for ABS enabled is
> often slightly less than for disabled.
I always say that if you can't make the leap of trusting the system,
that you are better off without ABS. What I find particularly dangerous,
is switching between rigs that have it and those that don't. That is
one of the reasons that my one wheel drive pickup is parked until spring,
in addition to the fact that it is a slug in the winter and lacks the
traction to get out of its own way.
> Which is why some vehicles have added yaw and slew rate controls
> on top of ABS... drivers with none of the mandatory "body learning"
> type experience it takes to learn how to use ABS...or not use it.
Eventually they will probably invent a vehicle which will totally take
driving ability out of the equation. I'm only in favor of that if they
will still let me drive my old stuff on the road.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
> If the computer is purely ABS, that may be true for you, but
> it has been proven to be not true for everybody. Particularly
> in off-road situations where even a lockwheel stop is faster
> than an ABS one--with today's control systems for ABS. And
> on some slippery surfaces, racing drivers can beat ABS sometimes.
I will never have the ability to modulate the pressure applied to the
calipers and wheel cylinders individually like the ABS system can. Also,
I may do pretty good on a good day, but I may not be having a good day.
The computer has the same day, every day. On my previous rig, when the
ABS computer was having a bad day, it reverted to standard brakes and
the warning light came on advising me of this.
One thing which I read once but haven't taken the time to confirm, is
that ABS is banned in formula one racing because it allows mediocre
drivers to be competitive with the better drivers.
> As for training, lecture style training even with visual aids
> and movies has demonstrated no improvement in driver use of ABS.
> They still do it wrong. Which may be why it is impossible to
> get a racing license without instructor observed track time
> where you bend the shiny parts until you figure out how not to.
Well, that is the problem with lecture style training. It needs to be
followed by practical training. I personally have practiced on deserted
roads and parking lots to get a feel for how the ABS reacts when I am
not in danger of hitting something. My reaction to the ABS isn't yet as
fast as my reaction to a skid (guess which I spend more time practicing,
heheheh), but I don't have to think about it either, I recognize the hum
and mash the pedal.
Just because the training used is not effective, doesn't invalidate the
concept of getting training. Another thing which I do and recommend, is
occasionally TEST the ABS to make sure it is actually still working
before it is needed.
> Seems the biggest contribution to ABS accidents is that the ABS
> allows the driver's insanely suicidal steering inputs to actually
> have effect, whereas the same driver without ABS will usually
> have the front wheels skidding enough that steering input
> has far lower effect.
Once again, that is an issue that could be solved through effective
training. Probably never will, but it is hardly the fault of the
mechanical device in question.
> Plus the drivers refuse to trust the
> ABS and keep it engaged. Braking time for ABS enabled is
> often slightly less than for disabled.
I always say that if you can't make the leap of trusting the system,
that you are better off without ABS. What I find particularly dangerous,
is switching between rigs that have it and those that don't. That is
one of the reasons that my one wheel drive pickup is parked until spring,
in addition to the fact that it is a slug in the winter and lacks the
traction to get out of its own way.
> Which is why some vehicles have added yaw and slew rate controls
> on top of ABS... drivers with none of the mandatory "body learning"
> type experience it takes to learn how to use ABS...or not use it.
Eventually they will probably invent a vehicle which will totally take
driving ability out of the equation. I'm only in favor of that if they
will still let me drive my old stuff on the road.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
Mike Romain wrote:
> A total lock of the wheels is the fastest stop, period.
Although it is mostly academic, that statement is false.
Static friction is always equal to or higher than sliding friction:
<http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>
One condition under which your statement is true is when the surface the
vehicle on is loose. On loose material where the tire can push a pile of
that material up in front of itself the resulting friction of the tire
*and* the material sliding together can be higher than the static
friction available on the loose surface alone.
On the road locking your wheels will always make the stopping distance
longer than it needs to be. Many people are not good enough drivers to
actually apply this maximum breaking force without locking the wheels.
In their case your statement may also often be true for that combination
of vehicle, road, and driver.
What modern ABS tried to do, to varying degrees of success, is hold the
breaking force below the force required to cause the tire to slip. In
actuality the tire does slip and the decrease in speed for that tire
caused by the slippage is what the ABS sensor looks for to decide how
much breaking force to use on each wheel.
However, the systems are a compromise. If you are in a turn for instance
the outside wheels need to rotate faster, as do the rear. This means
the outside rear is going significantly faster than the inside front. To
permit this to happen a simple ABS system needs to allow for small
differences in tire speeds. This makes those systems lock the wheels
even more.
Very advanced systems in the newest cars have accelerometers to measure
lateral acceleration in a turn as well as steering input sensors to
determine how much you are turning the wheel. These systems do a much
better job. Often they are marketed as 'stability control' because they
can also control engine speed and apply breaking force to keep you on
the correct track even if you don't apply the breaks yourself (such as
when you come off a highway too fast on a decreasing radius turn and
start to slide to the outside of the turn.)
> A total lock of the wheels is the fastest stop, period.
Although it is mostly academic, that statement is false.
Static friction is always equal to or higher than sliding friction:
<http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>
One condition under which your statement is true is when the surface the
vehicle on is loose. On loose material where the tire can push a pile of
that material up in front of itself the resulting friction of the tire
*and* the material sliding together can be higher than the static
friction available on the loose surface alone.
On the road locking your wheels will always make the stopping distance
longer than it needs to be. Many people are not good enough drivers to
actually apply this maximum breaking force without locking the wheels.
In their case your statement may also often be true for that combination
of vehicle, road, and driver.
What modern ABS tried to do, to varying degrees of success, is hold the
breaking force below the force required to cause the tire to slip. In
actuality the tire does slip and the decrease in speed for that tire
caused by the slippage is what the ABS sensor looks for to decide how
much breaking force to use on each wheel.
However, the systems are a compromise. If you are in a turn for instance
the outside wheels need to rotate faster, as do the rear. This means
the outside rear is going significantly faster than the inside front. To
permit this to happen a simple ABS system needs to allow for small
differences in tire speeds. This makes those systems lock the wheels
even more.
Very advanced systems in the newest cars have accelerometers to measure
lateral acceleration in a turn as well as steering input sensors to
determine how much you are turning the wheel. These systems do a much
better job. Often they are marketed as 'stability control' because they
can also control engine speed and apply breaking force to keep you on
the correct track even if you don't apply the breaks yourself (such as
when you come off a highway too fast on a decreasing radius turn and
start to slide to the outside of the turn.)
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
Mike Romain wrote:
> A total lock of the wheels is the fastest stop, period.
Although it is mostly academic, that statement is false.
Static friction is always equal to or higher than sliding friction:
<http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>
One condition under which your statement is true is when the surface the
vehicle on is loose. On loose material where the tire can push a pile of
that material up in front of itself the resulting friction of the tire
*and* the material sliding together can be higher than the static
friction available on the loose surface alone.
On the road locking your wheels will always make the stopping distance
longer than it needs to be. Many people are not good enough drivers to
actually apply this maximum breaking force without locking the wheels.
In their case your statement may also often be true for that combination
of vehicle, road, and driver.
What modern ABS tried to do, to varying degrees of success, is hold the
breaking force below the force required to cause the tire to slip. In
actuality the tire does slip and the decrease in speed for that tire
caused by the slippage is what the ABS sensor looks for to decide how
much breaking force to use on each wheel.
However, the systems are a compromise. If you are in a turn for instance
the outside wheels need to rotate faster, as do the rear. This means
the outside rear is going significantly faster than the inside front. To
permit this to happen a simple ABS system needs to allow for small
differences in tire speeds. This makes those systems lock the wheels
even more.
Very advanced systems in the newest cars have accelerometers to measure
lateral acceleration in a turn as well as steering input sensors to
determine how much you are turning the wheel. These systems do a much
better job. Often they are marketed as 'stability control' because they
can also control engine speed and apply breaking force to keep you on
the correct track even if you don't apply the breaks yourself (such as
when you come off a highway too fast on a decreasing radius turn and
start to slide to the outside of the turn.)
> A total lock of the wheels is the fastest stop, period.
Although it is mostly academic, that statement is false.
Static friction is always equal to or higher than sliding friction:
<http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>
One condition under which your statement is true is when the surface the
vehicle on is loose. On loose material where the tire can push a pile of
that material up in front of itself the resulting friction of the tire
*and* the material sliding together can be higher than the static
friction available on the loose surface alone.
On the road locking your wheels will always make the stopping distance
longer than it needs to be. Many people are not good enough drivers to
actually apply this maximum breaking force without locking the wheels.
In their case your statement may also often be true for that combination
of vehicle, road, and driver.
What modern ABS tried to do, to varying degrees of success, is hold the
breaking force below the force required to cause the tire to slip. In
actuality the tire does slip and the decrease in speed for that tire
caused by the slippage is what the ABS sensor looks for to decide how
much breaking force to use on each wheel.
However, the systems are a compromise. If you are in a turn for instance
the outside wheels need to rotate faster, as do the rear. This means
the outside rear is going significantly faster than the inside front. To
permit this to happen a simple ABS system needs to allow for small
differences in tire speeds. This makes those systems lock the wheels
even more.
Very advanced systems in the newest cars have accelerometers to measure
lateral acceleration in a turn as well as steering input sensors to
determine how much you are turning the wheel. These systems do a much
better job. Often they are marketed as 'stability control' because they
can also control engine speed and apply breaking force to keep you on
the correct track even if you don't apply the breaks yourself (such as
when you come off a highway too fast on a decreasing radius turn and
start to slide to the outside of the turn.)
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
Mike Romain wrote:
> A total lock of the wheels is the fastest stop, period.
Although it is mostly academic, that statement is false.
Static friction is always equal to or higher than sliding friction:
<http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>
One condition under which your statement is true is when the surface the
vehicle on is loose. On loose material where the tire can push a pile of
that material up in front of itself the resulting friction of the tire
*and* the material sliding together can be higher than the static
friction available on the loose surface alone.
On the road locking your wheels will always make the stopping distance
longer than it needs to be. Many people are not good enough drivers to
actually apply this maximum breaking force without locking the wheels.
In their case your statement may also often be true for that combination
of vehicle, road, and driver.
What modern ABS tried to do, to varying degrees of success, is hold the
breaking force below the force required to cause the tire to slip. In
actuality the tire does slip and the decrease in speed for that tire
caused by the slippage is what the ABS sensor looks for to decide how
much breaking force to use on each wheel.
However, the systems are a compromise. If you are in a turn for instance
the outside wheels need to rotate faster, as do the rear. This means
the outside rear is going significantly faster than the inside front. To
permit this to happen a simple ABS system needs to allow for small
differences in tire speeds. This makes those systems lock the wheels
even more.
Very advanced systems in the newest cars have accelerometers to measure
lateral acceleration in a turn as well as steering input sensors to
determine how much you are turning the wheel. These systems do a much
better job. Often they are marketed as 'stability control' because they
can also control engine speed and apply breaking force to keep you on
the correct track even if you don't apply the breaks yourself (such as
when you come off a highway too fast on a decreasing radius turn and
start to slide to the outside of the turn.)
> A total lock of the wheels is the fastest stop, period.
Although it is mostly academic, that statement is false.
Static friction is always equal to or higher than sliding friction:
<http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>
One condition under which your statement is true is when the surface the
vehicle on is loose. On loose material where the tire can push a pile of
that material up in front of itself the resulting friction of the tire
*and* the material sliding together can be higher than the static
friction available on the loose surface alone.
On the road locking your wheels will always make the stopping distance
longer than it needs to be. Many people are not good enough drivers to
actually apply this maximum breaking force without locking the wheels.
In their case your statement may also often be true for that combination
of vehicle, road, and driver.
What modern ABS tried to do, to varying degrees of success, is hold the
breaking force below the force required to cause the tire to slip. In
actuality the tire does slip and the decrease in speed for that tire
caused by the slippage is what the ABS sensor looks for to decide how
much breaking force to use on each wheel.
However, the systems are a compromise. If you are in a turn for instance
the outside wheels need to rotate faster, as do the rear. This means
the outside rear is going significantly faster than the inside front. To
permit this to happen a simple ABS system needs to allow for small
differences in tire speeds. This makes those systems lock the wheels
even more.
Very advanced systems in the newest cars have accelerometers to measure
lateral acceleration in a turn as well as steering input sensors to
determine how much you are turning the wheel. These systems do a much
better job. Often they are marketed as 'stability control' because they
can also control engine speed and apply breaking force to keep you on
the correct track even if you don't apply the breaks yourself (such as
when you come off a highway too fast on a decreasing radius turn and
start to slide to the outside of the turn.)
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
On 09 Dec 2003 07:30 PM, CRWLR posted the following:
> Don't get me wrong, ABS is a great thing to have. But, its main
> function is to maintain directional stability (which you illusatrate
> very well), even if the expense is a possibly longer stopping time and
> distance. Face it, if the choice is sliding sideways down the road, or
> steerinig around an approaching obsticle, I'll take the steering
> around stuff any day, even if it adds a few feet to the stopping
> distance.
That's fine. I disagree with the assertation that ABS leads to longer
stopping distances, but as long as we can discuss the pros and cons like
reasonable men I have no problem with the debate. What I don't like is
the misleading blanket statements that ABS is "crap" that a poster is
better off without, particularly when you may not be familiar with their
driving conditions or ability.
It is another tool in the toolbox. No tool devised by man will ever be
perfect.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
> Don't get me wrong, ABS is a great thing to have. But, its main
> function is to maintain directional stability (which you illusatrate
> very well), even if the expense is a possibly longer stopping time and
> distance. Face it, if the choice is sliding sideways down the road, or
> steerinig around an approaching obsticle, I'll take the steering
> around stuff any day, even if it adds a few feet to the stopping
> distance.
That's fine. I disagree with the assertation that ABS leads to longer
stopping distances, but as long as we can discuss the pros and cons like
reasonable men I have no problem with the debate. What I don't like is
the misleading blanket statements that ABS is "crap" that a poster is
better off without, particularly when you may not be familiar with their
driving conditions or ability.
It is another tool in the toolbox. No tool devised by man will ever be
perfect.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
On 09 Dec 2003 07:30 PM, CRWLR posted the following:
> Don't get me wrong, ABS is a great thing to have. But, its main
> function is to maintain directional stability (which you illusatrate
> very well), even if the expense is a possibly longer stopping time and
> distance. Face it, if the choice is sliding sideways down the road, or
> steerinig around an approaching obsticle, I'll take the steering
> around stuff any day, even if it adds a few feet to the stopping
> distance.
That's fine. I disagree with the assertation that ABS leads to longer
stopping distances, but as long as we can discuss the pros and cons like
reasonable men I have no problem with the debate. What I don't like is
the misleading blanket statements that ABS is "crap" that a poster is
better off without, particularly when you may not be familiar with their
driving conditions or ability.
It is another tool in the toolbox. No tool devised by man will ever be
perfect.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
> Don't get me wrong, ABS is a great thing to have. But, its main
> function is to maintain directional stability (which you illusatrate
> very well), even if the expense is a possibly longer stopping time and
> distance. Face it, if the choice is sliding sideways down the road, or
> steerinig around an approaching obsticle, I'll take the steering
> around stuff any day, even if it adds a few feet to the stopping
> distance.
That's fine. I disagree with the assertation that ABS leads to longer
stopping distances, but as long as we can discuss the pros and cons like
reasonable men I have no problem with the debate. What I don't like is
the misleading blanket statements that ABS is "crap" that a poster is
better off without, particularly when you may not be familiar with their
driving conditions or ability.
It is another tool in the toolbox. No tool devised by man will ever be
perfect.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
Guest
Posts: n/a
Re: Order Jeep -> Lose Rebate??
On 09 Dec 2003 07:30 PM, CRWLR posted the following:
> Don't get me wrong, ABS is a great thing to have. But, its main
> function is to maintain directional stability (which you illusatrate
> very well), even if the expense is a possibly longer stopping time and
> distance. Face it, if the choice is sliding sideways down the road, or
> steerinig around an approaching obsticle, I'll take the steering
> around stuff any day, even if it adds a few feet to the stopping
> distance.
That's fine. I disagree with the assertation that ABS leads to longer
stopping distances, but as long as we can discuss the pros and cons like
reasonable men I have no problem with the debate. What I don't like is
the misleading blanket statements that ABS is "crap" that a poster is
better off without, particularly when you may not be familiar with their
driving conditions or ability.
It is another tool in the toolbox. No tool devised by man will ever be
perfect.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/
> Don't get me wrong, ABS is a great thing to have. But, its main
> function is to maintain directional stability (which you illusatrate
> very well), even if the expense is a possibly longer stopping time and
> distance. Face it, if the choice is sliding sideways down the road, or
> steerinig around an approaching obsticle, I'll take the steering
> around stuff any day, even if it adds a few feet to the stopping
> distance.
That's fine. I disagree with the assertation that ABS leads to longer
stopping distances, but as long as we can discuss the pros and cons like
reasonable men I have no problem with the debate. What I don't like is
the misleading blanket statements that ABS is "crap" that a poster is
better off without, particularly when you may not be familiar with their
driving conditions or ability.
It is another tool in the toolbox. No tool devised by man will ever be
perfect.
----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/