TfL to possibly buy 200 extra New Bus for London
 

In message

, at 16:30:11 on Sun, 26 Oct 2014, Recliner
remarked:
Independently and momentarily applying the individual brakes probably is
more effective for regaining traction than locking the diff, not that many
two-wheel drive cars have locking diffs.

Not permanently locked ones, but a brake in the diff (rather that at the wheel).

A permanently locked differential isn't a differential at all, but a solid
axle.

Tell that to people with manual diff-locks on their Land Rovers (or
don't you count that as "permanent" - it is rather because you have to
stop to disengage it)?

A locking diff is one where there is resistance to the turning of one
wheel vis a vis the other, which can be either mechanically or electrically
controlled. But ASC (including traction control) are much more capable and
sophisticated, which is one reason why so few two-wheel drive cars now have
locking diffs.

I'm still not convinced that ASC is the same as traction control. It
sounds to me more like a variant of ABS (in other words it controls
stopping rather than "going").
--
Roland Perry

TfL to possibly buy 200 extra New Bus for London
 

In message , at 18:39:30 on Sun, 26
Oct 2014, Neil Williams remarked:
I would hope that proper traction control fed the power the most
suitable wheels, without having to rely upon brakes on the least
suitable wheels absorbing 100HP that the electronics says should be
suppressed.

Your hope would be misplaced. But do some reading on how a
differential works

I'm well aware of how differentials work, both left/right and front/back
ones.

- it has exactly the same effect with a massive reduction in complexity
over what you propose. Essentially the brake is not having to absorb
anything.

If you want 75% of the power put on the road through the left wheel, and
25% through the right wheel, how does braking the right wheel achieve
that without absorbing some of the engine power?
--
Roland Perry

TfL to possibly buy 200 extra New Bus for London
 

On 2014-10-27 08:02:43 +0000, Roland Perry said:

Braking a wheel isn't the same as locking a diff. Apart from anything
else, the locked diff still powers both wheels.

Though achieves nothing by doing so, as it is spinning.

Neil
--
Neil Williams
Put my first name before the @ to reply.

TfL to possibly buy 200 extra New Bus for London
 

On 2014-10-27 08:11:28 +0000, Roland Perry said:

If you want 75% of the power put on the road through the left wheel,
and 25% through the right wheel, how does braking the right wheel
achieve that without absorbing some of the engine power?

It will need to apply a small force to the wheel, but I can't see why
it would absorb any significant power as that would just go to the
other wheel via the diff.

Neil
--
Neil Williams
Put my first name before the @ to reply.

TfL to possibly buy 200 extra New Bus for London
 

Roland Perry wrote:
In message
, at 16:30:11 on Sun, 26 Oct 2014, Recliner remarked:
Independently and momentarily applying the individual brakes probably is
more effective for regaining traction than locking the diff, not that many
two-wheel drive cars have locking diffs.

Not permanently locked ones, but a brake in the diff (rather that at the wheel).

A permanently locked differential isn't a differential at all, but a solid
axle.

Tell that to people with manual diff-locks on their Land Rovers (or don't
you count that as "permanent" - it is rather because you have to stop to disengage it)?

A locking diff is one where there is resistance to the turning of one
wheel vis a vis the other, which can be either mechanically or electrically
controlled. But ASC (including traction control) are much more capable and
sophisticated, which is one reason why so few two-wheel drive cars now have
locking diffs.

I'm still not convinced that ASC is the same as traction control. It
sounds to me more like a variant of ABS (in other words it controls
stopping rather than "going").

ASC supersedes simple traction control, though it's sometimes called
traction control (that was the name used when I first got it, many years
ago, before the more sophisticated ASC superseded it). It reduces the
torque going to a wheel without traction, and hence controls traction. ASC
gets ever more sophisticated, and in some cars now includes torque
vectoring as well.

TfL to possibly buy 200 extra New Bus for London
 

Roland Perry wrote:
In message , at 18:42:49 on Sun, 26 Oct
2014, Neil Williams remarked:

Not permanently locked ones, but a brake in the diff (rather that at the wheel).

What would be gained by duplicating the function?

Braking a wheel isn't the same as locking a diff. Apart from anything
else, the locked diff still powers both wheels.

No it's not the same, but it's what traction control is. And ASC can still
power both wheels, independently reducing torque on each wheel to the level
that the tyre's grip can sustain. That provides more traction than a simple
locked diff.

TfL to possibly buy 200 extra New Bus for London
 

In message , at 08:35:17 on Mon, 27
Oct 2014, Neil Williams remarked:
Braking a wheel isn't the same as locking a diff. Apart from anything
else, the locked diff still powers both wheels.

Though achieves nothing by doing so, as it is spinning.

It means some power can be transmitted as soon as adhesion returns, but
most importantly because the diff is locked the other wheel is still
getting power.
--
Roland Perry

TfL to possibly buy 200 extra New Bus for London
 

In message

, at 03:39:08 on Mon, 27 Oct 2014, Recliner
remarked:
Not permanently locked ones, but a brake in the diff (rather that at the wheel).

What would be gained by duplicating the function?

Braking a wheel isn't the same as locking a diff. Apart from anything
else, the locked diff still powers both wheels.

No it's not the same, but it's what traction control is. And ASC can still
power both wheels, independently reducing torque on each wheel to the level
that the tyre's grip can sustain. That provides more traction than a simple
locked diff.

A locked diff is providing traction via the non-slipping wheel, except
the "slipping" one isn't - because it's rotating at the same speed as
the "non-slipping" one - and is therefore well placed to start providing
traction as soon as road adhesion returns to that side.
--
Roland Perry

TfL to possibly buy 200 extra New Bus for London
 

In message

, at 03:39:08 on Mon, 27 Oct 2014, Recliner
remarked:

ASC supersedes simple traction control, though it's sometimes called
traction control (that was the name used when I first got it, many years
ago, before the more sophisticated ASC superseded it). It reduces the
torque going to a wheel without traction,

It can only do that if the controlling element is in the differential.
Otherwise all the torque is still going to the wheel, but the brakes are
stopping the wheel from rotating too fast, which means those brakes are
absorbing the power, which is thus not (purposely it seems) available at
the road surface.

and hence controls traction. ASC gets ever more sophisticated, and in
some cars now includes torque vectoring as well.

--
Roland Perry

TfL to possibly buy 200 extra New Bus for London
 

In message , at 08:37:12 on Mon, 27
Oct 2014, Neil Williams remarked:
If you want 75% of the power put on the road through the left wheel,
and 25% through the right wheel, how does braking the right wheel
achieve that without absorbing some of the engine power?

It will need to apply a small force to the wheel, but I can't see why
it would absorb any significant power as that would just go to the
other wheel via the diff.

That sounds fine if you aren't attempting to put any power on the road
through the 'spinning' wheel. I'm looking at the case where you want
about half the power that would otherwise be sent through the rubber to
remain.
--
Roland Perry