color of spring

On Fri, 20 May 2016 09:48:23 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

They do have a parking brake

otherwise known as an emergency brake, and it works reasonably well if
the main brakes have failed. been there, done that.

You should compare stopping distances, especially if you take into
account the extra reaction time required to recognise that you have to
use the secondary braking system. That's without the complication of a
foot-operated parking brake.

the stopping distances of a brake that works is always going to be
better than a brake that does not work.

as for reaction time, that adds maybe a half-second.

Not so. SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

https://en.wikipedia.org/wiki/Braking_distance says "A
perception-reaction time of 1.5 seconds ... for the purpose of
determining a bare baseline for accident reconstruction".

Using the brake pedal is a trained reaction. The emergency use of a
hand brake is not and will take longer.

unfortunately, most drivers, when they realize their brakes failed,
will just panic and not do anything, ultimately slamming into whatever
is in front of them.

they'll even call it an accident, despite it being their own fault for
not knowing how to handle emergency situations as well as not
maintaining their vehicle such that there isn't a brake failure.

which
is a very weak reed to lean on.

it's weaker than the main brakes when the main brakes work and stronger
than the main brakes when they have failed.

Duh!

Anything is better than nothing but for many years main braking
systems have been duplex and cannot fail entirely unless the pedal
snaps off or similar.

nonsense.

Forget the standard diagram of braking systems. For a good many years
now braking systems have been split as in
http://vwts.ru/vw_doc/eva2/SU02/i23997.gif Front-left and back-right
are on one system while front-right and back-left are on another.
Failure in one system does not disable the other. There other systems
but complete brake failure is most unlikely in a modern vehicle.
--

Regards,

Eric Stevens

On Sat, 21 May 2016 12:46:14 +1200, Eric Stevens
wrote:

On Fri, 20 May 2016 09:48:23 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

They do have a parking brake

otherwise known as an emergency brake, and it works reasonably well if
the main brakes have failed. been there, done that.

You should compare stopping distances, especially if you take into
account the extra reaction time required to recognise that you have to
use the secondary braking system. That's without the complication of a
foot-operated parking brake.

the stopping distances of a brake that works is always going to be
better than a brake that does not work.

as for reaction time, that adds maybe a half-second.

Not so. SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

https://en.wikipedia.org/wiki/Braking_distance says "A
perception-reaction time of 1.5 seconds ... for the purpose of
determining a bare baseline for accident reconstruction".

Using the brake pedal is a trained reaction. The emergency use of a
hand brake is not and will take longer.

unfortunately, most drivers, when they realize their brakes failed,
will just panic and not do anything, ultimately slamming into whatever
is in front of them.

they'll even call it an accident, despite it being their own fault for
not knowing how to handle emergency situations as well as not
maintaining their vehicle such that there isn't a brake failure.

which
is a very weak reed to lean on.

it's weaker than the main brakes when the main brakes work and stronger
than the main brakes when they have failed.

Duh!

Anything is better than nothing but for many years main braking
systems have been duplex and cannot fail entirely unless the pedal
snaps off or similar.

nonsense.

Forget the standard diagram of braking systems. For a good many years
now braking systems have been split as in
http://vwts.ru/vw_doc/eva2/SU02/i23997.gif Front-left and back-right
are on one system while front-right and back-left are on another.
Failure in one system does not disable the other. There other systems
but complete brake failure is most unlikely in a modern vehicle.

That diagonal configuration is mainly to make sure you don't have to
stop with the rear brakes only. Front only will work just fine, but
rears only is like trying to stop with the park brake. Anyway, you
should always have at least one front brake, or no brakes at all.

In article , Eric Stevens
wrote:

They do have a parking brake

otherwise known as an emergency brake, and it works reasonably well if
the main brakes have failed. been there, done that.

You should compare stopping distances, especially if you take into
account the extra reaction time required to recognise that you have to
use the secondary braking system. That's without the complication of a
foot-operated parking brake.

the stopping distances of a brake that works is always going to be
better than a brake that does not work.

as for reaction time, that adds maybe a half-second.

Not so.

yes so.

SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

then they need to update their numbers.

http://www.humanbenchmark.com/tests/reactiontime/statistics
Since this site was created, it's recorded 31,003,876 reaction time
clicks.
The median reaction time is 265 milliseconds.
The average reaction time is 275 milliseconds.

note that the chart only goes up to 500ms, as anything beyond that
would be negligible.

anyone who has a 2 second reaction time should *not* be driving under
any circumstances. at 60 mph, they'll cover nearly a football field in
those 2 seconds. they're much worse than a drunk driver. they're a
disaster waiting to happen.

https://en.wikipedia.org/wiki/Braking_distance says "A
perception-reaction time of 1.5 seconds ... for the purpose of
determining a bare baseline for accident reconstruction".

they're reconstructing a crash *because* the driver took that long to
react.

even a drunk will react in less than 1.5 seconds. a texting driver is
also less, although not by much.

http://www.eweek.com/c/a/Mobile-and-...ers-Have-Slowe
r-Reaction-Times-than-Drunk-Drivers-131627
At 70 mph, Alterman's baseline reaction time was 0.56 of a second.
Calculating that a vehicle moving at 70 mph travels 103 feet every
second, while driving under the influence, Alterman's reaction time
slowed to 0.60 of a second, or an extra 4 feet traveled. While
reading a text, his reaction time slowed to 0.91 seconds, or a
distance of 36 extra feet traveled, and while texting and driving his
reaction time was 1.24 seconds-a difference of 70 extra feet.

Using the brake pedal is a trained reaction. The emergency use of a
hand brake is not and will take longer.

exactly why practicing evasive maneuvers in a safe environment (e.g.,
an empty parking lot) so that it becomes instinctive is vital. then
when it happens for real, the reaction is automatic, without any
unnecessary delay.



which
is a very weak reed to lean on.

it's weaker than the main brakes when the main brakes work and stronger
than the main brakes when they have failed.

Duh!

Anything is better than nothing but for many years main braking
systems have been duplex and cannot fail entirely unless the pedal
snaps off or similar.

nonsense.

Forget the standard diagram of braking systems. For a good many years
now braking systems have been split as in
http://vwts.ru/vw_doc/eva2/SU02/i23997.gif Front-left and back-right
are on one system while front-right and back-left are on another.
Failure in one system does not disable the other. There other systems
but complete brake failure is most unlikely in a modern vehicle.

unlikely or not, it still can happen.

pretending that it won't happen just means that if it does, you'll
crash instead of safely stopping.

you remind me of al haynes, the pilot on ua232 which crashed in sioux
city iowa in 1989 after losing all hydraulics. i heard him speak, and
one of the things that stuck with me was when he contacted atc to
declare an emergency, atc didn't believe that he lost *all* systems,
saying that was 1 in 100 million chance (or whatever number it was). he
said, well, i'm *that* one.

fortunately for all involved, he handled it exceptionally well.

On Fri, 20 May 2016 17:57:24 -0700, Bill W
wrote:

On Sat, 21 May 2016 12:46:14 +1200, Eric Stevens
wrote:

On Fri, 20 May 2016 09:48:23 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

They do have a parking brake

otherwise known as an emergency brake, and it works reasonably well if
the main brakes have failed. been there, done that.

You should compare stopping distances, especially if you take into
account the extra reaction time required to recognise that you have to
use the secondary braking system. That's without the complication of a
foot-operated parking brake.

the stopping distances of a brake that works is always going to be
better than a brake that does not work.

as for reaction time, that adds maybe a half-second.

Not so. SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

https://en.wikipedia.org/wiki/Braking_distance says "A
perception-reaction time of 1.5 seconds ... for the purpose of
determining a bare baseline for accident reconstruction".

Using the brake pedal is a trained reaction. The emergency use of a
hand brake is not and will take longer.

unfortunately, most drivers, when they realize their brakes failed,
will just panic and not do anything, ultimately slamming into whatever
is in front of them.

they'll even call it an accident, despite it being their own fault for
not knowing how to handle emergency situations as well as not
maintaining their vehicle such that there isn't a brake failure.

which
is a very weak reed to lean on.

it's weaker than the main brakes when the main brakes work and stronger
than the main brakes when they have failed.

Duh!

Anything is better than nothing but for many years main braking
systems have been duplex and cannot fail entirely unless the pedal
snaps off or similar.

nonsense.

Forget the standard diagram of braking systems. For a good many years
now braking systems have been split as in
http://vwts.ru/vw_doc/eva2/SU02/i23997.gif Front-left and back-right
are on one system while front-right and back-left are on another.
Failure in one system does not disable the other. There other systems
but complete brake failure is most unlikely in a modern vehicle.

That diagonal configuration is mainly to make sure you don't have to
stop with the rear brakes only. Front only will work just fine, but
rears only is like trying to stop with the park brake. Anyway, you
should always have at least one front brake, or no brakes at all.

You are correct but the idea is that if you have to lose half your
brakes in a failure it's better not to lose both your front brakes or
all your brakes one side.
--

Regards,

Eric Stevens

On Sat, 21 May 2016 15:30:19 +1200, Eric Stevens
wrote:

On Fri, 20 May 2016 17:57:24 -0700, Bill W
wrote:

On Sat, 21 May 2016 12:46:14 +1200, Eric Stevens
wrote:

On Fri, 20 May 2016 09:48:23 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

They do have a parking brake

otherwise known as an emergency brake, and it works reasonably well if
the main brakes have failed. been there, done that.

You should compare stopping distances, especially if you take into
account the extra reaction time required to recognise that you have to
use the secondary braking system. That's without the complication of a
foot-operated parking brake.

the stopping distances of a brake that works is always going to be
better than a brake that does not work.

as for reaction time, that adds maybe a half-second.

Not so. SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

https://en.wikipedia.org/wiki/Braking_distance says "A
perception-reaction time of 1.5 seconds ... for the purpose of
determining a bare baseline for accident reconstruction".

Using the brake pedal is a trained reaction. The emergency use of a
hand brake is not and will take longer.

unfortunately, most drivers, when they realize their brakes failed,
will just panic and not do anything, ultimately slamming into whatever
is in front of them.

they'll even call it an accident, despite it being their own fault for
not knowing how to handle emergency situations as well as not
maintaining their vehicle such that there isn't a brake failure.

which
is a very weak reed to lean on.

it's weaker than the main brakes when the main brakes work and stronger
than the main brakes when they have failed.

Duh!

Anything is better than nothing but for many years main braking
systems have been duplex and cannot fail entirely unless the pedal
snaps off or similar.

nonsense.

Forget the standard diagram of braking systems. For a good many years
now braking systems have been split as in
http://vwts.ru/vw_doc/eva2/SU02/i23997.gif Front-left and back-right
are on one system while front-right and back-left are on another.
Failure in one system does not disable the other. There other systems
but complete brake failure is most unlikely in a modern vehicle.

That diagonal configuration is mainly to make sure you don't have to
stop with the rear brakes only. Front only will work just fine, but
rears only is like trying to stop with the park brake. Anyway, you
should always have at least one front brake, or no brakes at all.

You are correct but the idea is that if you have to lose half your
brakes in a failure it's better not to lose both your front brakes or
all your brakes one side.

Yep - I omitted that second part.

On Fri, 20 May 2016 22:05:43 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

They do have a parking brake

otherwise known as an emergency brake, and it works reasonably well if
the main brakes have failed. been there, done that.

You should compare stopping distances, especially if you take into
account the extra reaction time required to recognise that you have to
use the secondary braking system. That's without the complication of a
foot-operated parking brake.

the stopping distances of a brake that works is always going to be
better than a brake that does not work.

as for reaction time, that adds maybe a half-second.

Not so.

yes so.

SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

then they need to update their numbers.

http://www.humanbenchmark.com/tests/reactiontime/statistics
Since this site was created, it's recorded 31,003,876 reaction time
clicks.
The median reaction time is 265 milliseconds.
The average reaction time is 275 milliseconds.

note that the chart only goes up to 500ms, as anything beyond that
would be negligible.

That's for someone expecting something to happen and mentally prepared
to react as soon as it does. The SAE figures are based on John Doe
trundling down the highway and having a dangerous situation suddenly
presented to him without warning. The first thing John Doe has to do
is to recognise that he is being presented with a situation to which
he has to react. Only after that does the reaction time start running.
That's why I referred to it as 'perception/reaction' time. If you are
driving down the road and have cause to brake and then, in the midst
of braking you have your brake system fail, you first have to perceive
that you have a situation to react to. You then have to work out what
to do about it and react. I would expect that it would take you at
least 2 seconds from brake failure to you applying the parking brake.

anyone who has a 2 second reaction time should *not* be driving under
any circumstances. at 60 mph, they'll cover nearly a football field in
those 2 seconds. they're much worse than a drunk driver. they're a
disaster waiting to happen.

https://en.wikipedia.org/wiki/Braking_distance says "A
perception-reaction time of 1.5 seconds ... for the purpose of
determining a bare baseline for accident reconstruction".

That's a simplistic analysis. 1.5 seconds is not unreasonable for but
neither is 2 seconds. The SAE figures are based on actual tests with
ordinary drivers. The model does not take into account that it takes
several revolutions of the wheels for brakes to become fully applied.
A coefficient of friction of 0.7 is low with actual tests on good road
surfaces giving figures of 0.9 or higher.

they're reconstructing a crash *because* the driver took that long to
react.

even a drunk will react in less than 1.5 seconds. a texting driver is
also less, although not by much.

http://www.eweek.com/c/a/Mobile-and-...ers-Have-Slowe
r-Reaction-Times-than-Drunk-Drivers-131627
At 70 mph, Alterman's baseline reaction time was 0.56 of a second.
Calculating that a vehicle moving at 70 mph travels 103 feet every
second, while driving under the influence, Alterman's reaction time
slowed to 0.60 of a second, or an extra 4 feet traveled. While
reading a text, his reaction time slowed to 0.91 seconds, or a
distance of 36 extra feet traveled, and while texting and driving his
reaction time was 1.24 seconds-a difference of 70 extra feet.

Using the brake pedal is a trained reaction. The emergency use of a
hand brake is not and will take longer.

exactly why practicing evasive maneuvers in a safe environment (e.g.,
an empty parking lot) so that it becomes instinctive is vital. then
when it happens for real, the reaction is automatic, without any
unnecessary delay.



which
is a very weak reed to lean on.

it's weaker than the main brakes when the main brakes work and stronger
than the main brakes when they have failed.

Duh!

Anything is better than nothing but for many years main braking
systems have been duplex and cannot fail entirely unless the pedal
snaps off or similar.

nonsense.

Forget the standard diagram of braking systems. For a good many years
now braking systems have been split as in
http://vwts.ru/vw_doc/eva2/SU02/i23997.gif Front-left and back-right
are on one system while front-right and back-left are on another.
Failure in one system does not disable the other. There other systems
but complete brake failure is most unlikely in a modern vehicle.

unlikely or not, it still can happen.

pretending that it won't happen just means that if it does, you'll
crash instead of safely stopping.

you remind me of al haynes, the pilot on ua232 which crashed in sioux
city iowa in 1989 after losing all hydraulics. i heard him speak, and
one of the things that stuck with me was when he contacted atc to
declare an emergency, atc didn't believe that he lost *all* systems,
saying that was 1 in 100 million chance (or whatever number it was). he
said, well, i'm *that* one.

fortunately for all involved, he handled it exceptionally well.

Fortunately for all involved, he had time to enable him to handle it
exceptionally well.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:


SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

then they need to update their numbers.

http://www.humanbenchmark.com/tests/reactiontime/statistics
Since this site was created, it's recorded 31,003,876 reaction time
clicks.
The median reaction time is 265 milliseconds.
The average reaction time is 275 milliseconds.

note that the chart only goes up to 500ms, as anything beyond that
would be negligible.

That's for someone expecting something to happen and mentally prepared
to react as soon as it does.

anyone who is driving should *always* be expecting something to happen
and mentally prepared to react as soon as it does.

and people wonder why there are so many collisions.

**** happens when you least expect it, whether it's mechanical failure
or a kid running into the street or an idiot running a red light.

when it does, you don't have time to decide what to do. a split second
can make all the difference and you don't get a second chance either.

The SAE figures are based on John Doe
trundling down the highway and having a dangerous situation suddenly
presented to him without warning. The first thing John Doe has to do
is to recognise that he is being presented with a situation to which
he has to react. Only after that does the reaction time start running.

john doe needs to stop driving, as he's putting everyone in danger.

That's why I referred to it as 'perception/reaction' time. If you are
driving down the road and have cause to brake and then, in the midst
of braking you have your brake system fail, you first have to perceive
that you have a situation to react to. You then have to work out what
to do about it and react. I would expect that it would take you at
least 2 seconds from brake failure to you applying the parking brake.

not for me it won't.

the moment i apply the brakes and nothing happens is the moment i
engage the emergency brake and/or downshift in at most, a half-second.

add that to the initial reaction time and the total is around 1 second
or so.

the whole reason i practice this stuff is so that i react *before* it's
too late.

On Sat, 21 May 2016 00:40:49 -0400, nospam
wrote:

In article , Eric Stevens
wrote:


SAE allows at least 2 seconds for perception/reaction time.
Stretching it to 2.5 seconds may be accepted.

then they need to update their numbers.

http://www.humanbenchmark.com/tests/reactiontime/statistics
Since this site was created, it's recorded 31,003,876 reaction time
clicks.
The median reaction time is 265 milliseconds.
The average reaction time is 275 milliseconds.

note that the chart only goes up to 500ms, as anything beyond that
would be negligible.

That's for someone expecting something to happen and mentally prepared
to react as soon as it does.

anyone who is driving should *always* be expecting something to happen
and mentally prepared to react as soon as it does.

So you drive around expecting your foot brake to fail. At the same
time you are prepared for red light runners. How do you cope with that
while watching for approaching traffic crossing over into your lane?
Your nerves must be totally frazzled.

and people wonder why there are so many collisions.

**** happens when you least expect it, whether it's mechanical failure
or a kid running into the street or an idiot running a red light.

How do reconcile "least expect it" with "should *always* be expecting
something to happen"?

when it does, you don't have time to decide what to do. a split second
can make all the difference and you don't get a second chance either.

The SAE figures are based on John Doe
trundling down the highway and having a dangerous situation suddenly
presented to him without warning. The first thing John Doe has to do
is to recognise that he is being presented with a situation to which
he has to react. Only after that does the reaction time start running.

john doe needs to stop driving, as he's putting everyone in danger.

So you expect instaneous recognition of an unexpected hazard?

That's why I referred to it as 'perception/reaction' time. If you are
driving down the road and have cause to brake and then, in the midst
of braking you have your brake system fail, you first have to perceive
that you have a situation to react to. You then have to work out what
to do about it and react. I would expect that it would take you at
least 2 seconds from brake failure to you applying the parking brake.

not for me it won't.

the moment i apply the brakes and nothing happens is the moment i
engage the emergency brake and/or downshift in at most, a half-second.

How do you change gear and apply the parking brake simultaneously with
the same hand?

add that to the initial reaction time and the total is around 1 second
or so.

the whole reason i practice this stuff is so that i react *before* it's
too late.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

note that the chart only goes up to 500ms, as anything beyond that
would be negligible.

That's for someone expecting something to happen and mentally prepared
to react as soon as it does.

anyone who is driving should *always* be expecting something to happen
and mentally prepared to react as soon as it does.

So you drive around expecting your foot brake to fail. At the same
time you are prepared for red light runners. How do you cope with that
while watching for approaching traffic crossing over into your lane?

i'm prepared for anything that might happen.

Your nerves must be totally frazzled.

not at all.

and people wonder why there are so many collisions.

**** happens when you least expect it, whether it's mechanical failure
or a kid running into the street or an idiot running a red light.

How do reconcile "least expect it" with "should *always* be expecting
something to happen"?

they're the same thing.

when it does, you don't have time to decide what to do. a split second
can make all the difference and you don't get a second chance either.

The SAE figures are based on John Doe
trundling down the highway and having a dangerous situation suddenly
presented to him without warning. The first thing John Doe has to do
is to recognise that he is being presented with a situation to which
he has to react. Only after that does the reaction time start running.

john doe needs to stop driving, as he's putting everyone in danger.

So you expect instaneous recognition of an unexpected hazard?

i'd like that to be the case, but realistically, i don't expect it from
others.

That's why I referred to it as 'perception/reaction' time. If you are
driving down the road and have cause to brake and then, in the midst
of braking you have your brake system fail, you first have to perceive
that you have a situation to react to. You then have to work out what
to do about it and react. I would expect that it would take you at
least 2 seconds from brake failure to you applying the parking brake.

not for me it won't.

the moment i apply the brakes and nothing happens is the moment i
engage the emergency brake and/or downshift in at most, a half-second.

How do you change gear and apply the parking brake simultaneously with
the same hand?

who said simultaneously? obviously one will precede the other.

the point is that there isn't a 2 second delay to figure out what to do
and when. it's an automatic response. it's a reflex.

On 2016-05-23 02:21:12 +0000, nospam said:

In article , Eric Stevens
wrote:

note that the chart only goes up to 500ms, as anything beyond that
would be negligible.

That's for someone expecting something to happen and mentally prepared
to react as soon as it does.

anyone who is driving should *always* be expecting something to happen
and mentally prepared to react as soon as it does.

So you drive around expecting your foot brake to fail. At the same
time you are prepared for red light runners. How do you cope with that
while watching for approaching traffic crossing over into your lane?

i'm prepared for anything that might happen.

A Trump presidency?


--
Regards,

Savageduck