On 23/07/2018 12:02, NY wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
* TMS320 wrote:
Turning off the ignition will turn off electric power steering. Not what
you want to add to your list of surprises.

You can still steer the car with no power assistance. It will just be
heavier. But not so heavy you can't steer it to the side of the road. And
far safer than trying to stop the car on the brakes while on full power.

Yes I've driven my car a couple of miles, including changing lanes,
coming off a motorway and going round a roundabout, with no PAS when the
fan belt broke. It was heavy. I had to plan ahead and grip the wheel
with both hands to get more torque on the wheel, but it was not
insurmountable. I wouldn't like to try it in a coach or HGV, though :-)

Is the heaviness of the steering when PAS is disabled due solely to
having to compress the PAS fluid on the "wrong" side of the piston that
gives power assistance? Or are cars with PAS made with inherently
heavier steering (different castor angle) to give greater precision and
feedback to the driver, in the knowledge that the PAS will more than
compensate for this heavier (but more responsive, more self-centring)
steering. I've heard two schools of thought about this.

There may be some hydraulic effects, but there is also a simple
mechanical reason - mechanical advantage. From my experience, non-PAS is
typically 3.5 turns lock to lock, while PAS is typically 2.5

Regards,
SteveW

In article ,
TMS320 wrote:
On 23/07/18 10:49, Dave Plowman (News) wrote:
In article , TMS320
wrote:

Turning off the ignition will turn off electric power steering. Not
what you want to add to your list of surprises.

You can still steer the car with no power assistance.

Sometimes it does no harm to assume there is some intelligence amongst
the readership and they don't need to be told the consequence of not
having assistance.

And far safer than trying to stop the car on the brakes while on full
power.

An engine is nowhere near powerful enough to overcome the brakes; it
would be just a matter of pressing the pedal harder than the foot is
normally calibrated to do. People don't routinely dial in more than
about a quarter g.

But why would you bother when it's simple to just turn off the ignition?
Surely the important thing is to get the car to a standstill as safely as
possible?

--
*If at first you don't succeed, try management *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
NY wrote:
I've always wondered how the left-foot braking thing ever came into
being. If you drive a manual car you are used to a fairly big movement
with your left foot, and finer, more precise movements with your right
foot to operate the brake or accelerator. Part of learning to drive is
acquiring the different muscle memory in your two feet.

Which bozo thought that it was sensible to operate the brake in an
automatic with your left foot, just because you won't need that foot
for the clutch? It means learning a whole new muscle memory, so as not
to press the brake as hard and as far as you would with the clutch,
only to have to unlearn this if you ever have to drive a manual.

Actually very simple. Why would you only use one foot when there are two
pedals?

Of course if you do have a problem reverting when driving a manual, best
not to. But you're just as likely to stall etc if you can't adapt to
driving both.

--
*Upon the advice of my attorney, my shirt bears no message at this time

Dave Plowman London SW
To e-mail, change noise into sound.

"NY" wrote in message
o.uk...
"Nick Finnigan" wrote in message
news
Well it's an auto, so you'll be left foot braking, and not think about
the accelerator in an emergency.

I've always wondered how the left-foot braking thing ever came into being.
If you drive a manual car you are used to a fairly big movement with your
left foot, and finer, more precise movements with your right foot to
operate the brake or accelerator. Part of learning to drive is acquiring
the different muscle memory in your two feet.

Which bozo thought that it was sensible to operate the brake in an
automatic with your left foot, just because you won't need that foot for
the clutch? It means learning a whole new muscle memory, so as not to
press the brake as hard and as far as you would with the clutch, only to
have to unlearn this if you ever have to drive a manual.

I have always used my right foot to brake in an automatic, exactly as I
would for a manual.

Me too and I never had a problem when most of the work vehicles
were autos. But now can have a problem driving an auto at times
when I pull up and use the clutch and jam the brakes on with an auto,
presumably because I drive autos much less frequently than I used to.

On 24/07/18 00:14, Dave Plowman (News) wrote:
In article ,
TMS320 wrote:
On 23/07/18 10:49, Dave Plowman (News) wrote:
In article , TMS320
wrote:

Turning off the ignition will turn off electric power steering. Not
what you want to add to your list of surprises.

You can still steer the car with no power assistance.

Sometimes it does no harm to assume there is some intelligence amongst
the readership and they don't need to be told the consequence of not
having assistance.

And far safer than trying to stop the car on the brakes while on full
power.

An engine is nowhere near powerful enough to overcome the brakes; it
would be just a matter of pressing the pedal harder than the foot is
normally calibrated to do. People don't routinely dial in more than
about a quarter g.

But why would you bother when it's simple to just turn off the ignition?
Surely the important thing is to get the car to a standstill as safely as
possible?

Yes, it is important to get the car to a standstill as safely as
possible. Why would you increase your workload to do something unusual
in a moment of stress instead of doing something routine?

On Tue, 24 Jul 2018 09:26:27 +1000, cantankerous senile geezer Rot Speed
blabbered, again:

Me too and I never had a problem when most of the work vehicles
were autos. But now can have a problem driving an auto at times
when I pull up and use the clutch and jam the brakes on with an auto,
presumably because I drive autos much less frequently than I used to.

Especially since you are getting driven around by your carers now, senile
oaf!

--
dennis@home to know-it-all Rot Speed:
"You really should stop commenting on things you know nothing about."
Message-ID:

On Tue, 24 Jul 2018 00:14:28 +0100, Dave Plowman (News) wrote:

But why would you bother when it's simple to just turn off the ignition?

'cause a diesel, burning it's own oil, will just carry on switched
off or not... B-)

Surely the important thing is to get the car to a standstill as safely
as possible?

So just use the foot brake a bit harder than normal to bring both car
and engine to a safe and controlled standstill.

The orginal start of this thread was based in the US. They mostly
drive automatics over there so the pigging thing will change down to
counter act the braking. Selecting N still doesn't strike me as
"right" though, selecting the highest fixed drive and braking ought
to work. Assuming the auto box and/or computers will allow that
change to happen with the engine under full throttle.

--
Cheers
Dave.

On Mon, 23 Jul 2018 15:26:03 +0100, Harry Bloomfield wrote:

Certainly the had cranked static diesels of the era, had a lever to
release the compression, so the could be cranked over. You moved the
lever, cranked up to speed then released the lever to hopefully have it
fire up.

Yep, my single cylinder diesel genset has a decompression lever so
(if your feeling fit) can pull start it. Try and pull it without
releasing the compression and it's like trying to pull the QE2. For
normal use It has electric start and battery kept topped up with
small solar panel. B-)

Possibly lorries had a similar device too, to allow the starter to crank
the engine over. Called a 'valve lifter' I think (?)..

Any diesel that is/was intended to be hand startable will have one.

Such a lever would stop a runaway diesel engine, if used on all
cylinders.

It'd have to operate on all cylinders to enable hand starting...

--
Cheers
Dave.

"Dave Liquorice" wrote in message
idual.net...
On Tue, 24 Jul 2018 00:14:28 +0100, Dave Plowman (News) wrote:

But why would you bother when it's simple to just turn off the ignition?

'cause a diesel, burning it's own oil, will just carry on switched
off or not... B-)

Surely the important thing is to get the car to a standstill as safely
as possible?

So just use the foot brake a bit harder than normal to bring both car
and engine to a safe and controlled standstill.

The orginal start of this thread was based in the US. They mostly
drive automatics over there so the pigging thing will change down to
counter act the braking. Selecting N still doesn't strike me as
"right" though, selecting the highest fixed drive and braking ought
to work. Assuming the auto box and/or computers will allow that
change to happen with the engine under full throttle.

Yes, the whole concept of removing the mechanical load from an engine that
is running out of control seems counter-intuitive, when the object would
seem to be to remove the problem at source by cutting off the fuel which is
best achieved by turning off the ignition. That hinges critically on not
accidentally locking the steering wheel: the thing that the video said was
highly likely but people on this thread have said doesn't happen until the
keys are removed - unless anyone knows of exceptions to that for certain
vehicles.

Braking the engine when it is transmitting power to the wheels will lead to
a "fight" between brakes and engine, with the risk that the energy that the
engine is generating will heat up brakes too much. If you have an engine
generating maybe 100 hp, you've got to dissipate that sort of energy in the
brakes. What is the effect of the discs heating up dramatically: can it
cause loss of braking force? They did mention something about "burning out
the brakes" which was the reason for contemplating using the "emergency
brake" instead, as if that magically used different pads and wouldn't be
affected in exactly the same way by brake heating.

In article ,
TMS320 wrote:
But why would you bother when it's simple to just turn off the ignition?
Surely the important thing is to get the car to a standstill as safely as
possible?

Yes, it is important to get the car to a standstill as safely as
possible. Why would you increase your workload to do something unusual
in a moment of stress instead of doing something routine?

Working out that turning off the engine if the throttle has suck open
increases your work load?

And it's certainly not natural to apply the brakes while the engine is
pulling hard. Unless a rally driver, etc.

--
*Being healthy is merely the slowest possible rate at which one can die.

Dave Plowman London SW
To e-mail, change noise into sound.

In article l.net,
Dave Liquorice wrote:
On Tue, 24 Jul 2018 00:14:28 +0100, Dave Plowman (News) wrote:

But why would you bother when it's simple to just turn off the ignition?

'cause a diesel, burning it's own oil, will just carry on switched
off or not... B-)

But that's not a stuck throttle. ;-) And I'd say pretty rare?

Surely the important thing is to get the car to a standstill as safely
as possible?

So just use the foot brake a bit harder than normal to bring both car
and engine to a safe and controlled standstill.

The orginal start of this thread was based in the US. They mostly
drive automatics over there so the pigging thing will change down to
counter act the braking. Selecting N still doesn't strike me as
"right" though, selecting the highest fixed drive and braking ought
to work. Assuming the auto box and/or computers will allow that
change to happen with the engine under full throttle.

As I said with my auto which as drive by wire throttle, if you brake with
the throttle pedal still pressed, it cuts the engine.

However, selecting neutral with any gearbox while the throttle is wide
open might well result in engine damage. So why risk that when you can
switch off the engine?

Basically we're talking older cars. Many modern ones are drive by wire, so
far less likely the throttle can stick open.

--
*Virtual reality is its own reward*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Liquorice" wrote in message
idual.net...
Possibly lorries had a similar device too, to allow the starter to crank
the engine over. Called a 'valve lifter' I think (?)..

Any diesel that is/was intended to be hand startable will have one.

Such a lever would stop a runaway diesel engine, if used on all
cylinders.

It'd have to operate on all cylinders to enable hand starting...

I'm always amazed that my car starts on a very cold morning when the oil
will presumably be more viscous. It sometimes takes longer to fire, but
apart from one time when the battery was on it last legs (wouldn't hold as
much charge) it turns over as fast as normal. I suppose once you get past
the first cylinder compression and over top dead centre, that stored
pressure will act in your favour and counteract the compression stroke that
is beginning on the next cylinder etc. But you have to overcome the first
compression stroke.

In article ,
NY wrote:
Yes, the whole concept of removing the mechanical load from an engine
that is running out of control seems counter-intuitive, when the object
would seem to be to remove the problem at source by cutting off the
fuel which is best achieved by turning off the ignition. That hinges
critically on not accidentally locking the steering wheel: the thing
that the video said was highly likely but people on this thread have
said doesn't happen until the keys are removed - unless anyone knows of
exceptions to that for certain vehicles.

I'd say any vehicle which locked the steering when you simply turned off
the ignition faulty. As well as positively dangerous.

--
*A journey of a thousand sites begins with a single click *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
Basically we're talking older cars. Many modern ones are drive by wire, so
far less likely the throttle can stick open.

I suppose any fault with the pedal position sensor that feeds info to the
ECU could cause the engine to race uncontrollably. However if you press the
brake, the ECU *may* be designed to cut the power on the basis that you
shouldn't be braking and accelerating at the same time - the ECU doesn't
know whether it's a stuck sensor or your foot hard on the throttle pedal.

A lot depends on where the sensor is. If it's in the footwell, right by the
pedal, it's less likely to stick. If it's at the far end of a bowden cable,
under the bonnet, as was the case on my first diesel car, then a frayed
cable *could* be a problem.

But, yes, I was talking about an older car with no ECU and a carburettor
which will carry on pumping fuel and air mixture as long as the cylinders
suck it in, and an engine that will carry on igniting the mixture until the
HT (or LT) is cut off.

My dad made a Heath Robinson immobiliser on one of his cars - I think it was
one of his Citroens. Since none of us smoke, he modified the cigarette
lighter with a steel disc that my grandpa turned on his lathe instead of the
normal heating element, and altered the wiring to put this "switch" in
series with the LT. Unless you pressed the cigarette lighter in, the car
would never fire. OK, so a savvy thief might hot-wire the coil directly to
the battery, but it would deter opportunistic thieves. He had to remember to
change the wiring back for when he sold the car :-)

That would have been a great kill switch in this situation: pull the
cigarette lighter out and the spark goes away, even though the key is still
in its original position and so there is power to everything except the
ignition. Not that he anticipated that need...

"Dave Plowman (News)" wrote in message
...
In article ,
NY wrote:
Yes, the whole concept of removing the mechanical load from an engine
that is running out of control seems counter-intuitive, when the object
would seem to be to remove the problem at source by cutting off the
fuel which is best achieved by turning off the ignition. That hinges
critically on not accidentally locking the steering wheel: the thing
that the video said was highly likely but people on this thread have
said doesn't happen until the keys are removed - unless anyone knows of
exceptions to that for certain vehicles.

I'd say any vehicle which locked the steering when you simply turned off
the ignition faulty. As well as positively dangerous.

Yes so would I. In the heat of the moment I wasn't going to risk it and so I
turned the switch off carefully to the accessory position - just in case.
But I would say that the steering should only lock if the key is removed,
not just turned off. There are various reasons why you may need to kill the
engine in a hurry - a passenger might need to do it if the driver becomes
incapacitated and keeps pressure on the accelerator. I've always thought
that cars should be designed with the ignition key on the side of the
steering column that is nearer the passenger, as was the case on first few
cars I owned. So LHD cars still have the ignition on the RHS, which is the
passenger's side for LHD? Or is that part of the steering column housing
mirrored for LHD? I know that indicator and wiper stalks are still the same
way round, which fooled me for a few seconds when I first drove an LHD
because I expected the stalks to be mirrored.

NY wrote:

Dave Liquorice wrote:

Any diesel that is/was intended to be hand startable will have one.
It'd have to operate on all cylinders to enable hand starting...

I'm always amazed that my car starts on a very cold morning when the oil
will presumably be more viscous. It sometimes takes longer to fire

I now have a stop-start car. For normal starts it uses the pinion-based
starter, once warmed up sufficiently that stop-start comes into
operation, it uses the alternator to re-start through the belt.

The stop-start takes a little getting used to (many factors that
influence whether it will or won't operate, such as aircon, steering
angle, gearbox mode, etc).

Annoyingly it's not fully predictable, e.g. you brake to a stop, the
engine stops, the hold-assist on the brakes kicks in (saving you from
having to apply the parking brake while preventing brake lights from
annoying the car behind) when you take your foot off the brake
*sometimes* the engine will restart immediately, surely it could have
worked out before stopping that it would need to restart, and not
bothered stopping?

On Mon, 23 Jul 2018 15:26:03 +0100, Harry Bloomfield wrote:

NY used his keyboard to write :
Was that ever done as a way of stalling an engine to turn it off. It
would have been in the late 60s, so whatever technology (mechanical
fuel pump and injectors) was around at the time. Not sure whether it
was 2-stroke (eg Commer "Knocker") or 4-stroke.

Certainly the had cranked static diesels of the era, had a lever to
release the compression, so the could be cranked over. You moved the
lever, cranked up to speed then released the lever to hopefully have it
fire up. Possibly lorries had a similar device too, to allow the starter
to crank the engine over. Called a 'valve lifter' I think (?)..

Correct. Also found on soem motorcycles (mainly big single cylinder
jobbies) to make kick starting easier.

I remember a friend of mine had a 500cc 'single' that seemed to do about
5 rpm!



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

"Andy Burns" wrote in message
...
NY wrote:

Dave Liquorice wrote:
Any diesel that is/was intended to be hand startable will have one.
It'd have to operate on all cylinders to enable hand starting...

I'm always amazed that my car starts on a very cold morning when the oil
will presumably be more viscous. It sometimes takes longer to fire

I now have a stop-start car. For normal starts it uses the pinion-based
starter, once warmed up sufficiently that stop-start comes into operation,
it uses the alternator to re-start through the belt.

The stop-start takes a little getting used to (many factors that influence
whether it will or won't operate, such as aircon, steering angle, gearbox
mode, etc).

Annoyingly it's not fully predictable, e.g. you brake to a stop, the
engine stops, the hold-assist on the brakes kicks in (saving you from
having to apply the parking brake while preventing brake lights from
annoying the car behind) when you take your foot off the brake *sometimes*
the engine will restart immediately, surely it could have worked out
before stopping that it would need to restart, and not bothered stopping?

Our Honda has stop-start which can be turned off if you want. I hadn't
realised it doesn't always use the starter motor to restart - maybe that's
model-dependant, because it sounds exactly the same noise as when the car is
started on the key.

I was apprehensive at first that the car wouldn't start quickly enough when
I was ready to set off, but I've never beaten it yet: by the time I've
pressed the clutch pedal (the trigger to restart), put the car into first
gear and lifted the clutch, the engine is running and the car sets off as if
the engine has been on al the time.

The car supposedly has hill start assist, which may also work when the car
is on a gradient when it is stopped due to auto-start, but I've never tried
it. I was taught to always apply the handbrake and go into neutral when I
stop; the only time I don't is if I anticipate that I'll be starting off
again in a few seconds.

What I have noticed with this car is that there is a horrendous about of
slack in the handbrake mechanism. If I brake to a halt on a gradient, apply
the handbrake and then release the footbrake, the car lurches forwards or
backwards (depending on gradient) before coming to a very sudden stop. It
feels like a lot of play, but it may only be an inch or so of rotation. It
makes it very difficult to stop smoothly on a gradient: I find that I have
to deliberately release the footbrake slowly so the car still rolls but at
least doesn't come up hard against the end-stop. The Honda garage couldn't
understand what I was complaining about and said that this was standard with
cars that have hill-start assist. I asked what was involved in disabling
hill-start assist so the car stays where it is when you brake to a halt,
apply the handbrake and then release the footbrake, but they said the design
doesn't allow for that. They seem to have done something that has reduced
the amount of play and/or reduced the ferocity of the sudden stop at the end
of the play, but it's still nowhere near as good as my old Peugeot with no
hill-start assist.

Sometimes you can have too much automation and assistance. Automation is
fine as long as you don't have to work around it and make allowances for it
not doing what a competent manual driver would do.

In article ,
NY wrote:
I suppose any fault with the pedal position sensor that feeds info to
the ECU could cause the engine to race uncontrollably.

They are rather more than a simple pot or position sensor. Designed to
fail safe.

--
*Money isn't everything, but it sure keeps the kids in touch.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andy Burns wrote:
I now have a stop-start car. For normal starts it uses the pinion-based
starter, once warmed up sufficiently that stop-start comes into
operation, it uses the alternator to re-start through the belt.

Interesting. One design I saw used an alternator built into the flywheel
or whatever. So no drive mechanism needed.

I'm rather surprised the drive belt is up to starting an engine.

--
*Why were the Indians here first? They had reservations.*

Dave Plowman London SW
To e-mail, change noise into sound.

"NY" wrote in message
o.uk...
"Dave Liquorice" wrote in message
idual.net...
On Tue, 24 Jul 2018 00:14:28 +0100, Dave Plowman (News) wrote:

But why would you bother when it's simple to just turn off the ignition?

'cause a diesel, burning it's own oil, will just carry on switched
off or not... B-)

Surely the important thing is to get the car to a standstill as safely
as possible?

So just use the foot brake a bit harder than normal to bring both car
and engine to a safe and controlled standstill.

The orginal start of this thread was based in the US. They mostly
drive automatics over there so the pigging thing will change down to
counter act the braking. Selecting N still doesn't strike me as
"right" though, selecting the highest fixed drive and braking ought
to work. Assuming the auto box and/or computers will allow that
change to happen with the engine under full throttle.

Yes, the whole concept of removing the mechanical load from an engine that
is running out of control seems counter-intuitive, when the object would
seem to be to remove the problem at source by cutting off the fuel which
is best achieved by turning off the ignition. That hinges critically on
not accidentally locking the steering wheel: the thing that the video said
was highly likely but people on this thread have said doesn't happen until
the keys are removed - unless anyone knows of exceptions to that for
certain vehicles.

Braking the engine when it is transmitting power to the wheels will lead
to a "fight" between brakes and engine, with the risk that the energy that
the engine is generating will heat up brakes too much. If you have an
engine generating maybe 100 hp, you've got to dissipate that sort of
energy in the brakes. What is the effect of the discs heating up
dramatically: can it cause loss of braking force?

Yep, same effect as brake fade when using them when going
down a long downhill run and using the brakes in that situation.

They did mention something about "burning out the brakes" which was the
reason for contemplating using the "emergency brake" instead, as if that
magically used different pads and wouldn't be affected in exactly the same
way by brake heating.

Yeah, they don't seem to have much of a clue about the basics.

On Tue, 24 Jul 2018 11:08:23 +0100
"NY" wrote:
"Andy Burns" wrote in message
...
NY wrote:

Dave Liquorice wrote:
Any diesel that is/was intended to be hand startable will have one.
It'd have to operate on all cylinders to enable hand starting...

I'm always amazed that my car starts on a very cold morning when the oil
will presumably be more viscous. It sometimes takes longer to fire

I now have a stop-start car. For normal starts it uses the pinion-based
starter, once warmed up sufficiently that stop-start comes into operation,
it uses the alternator to re-start through the belt.

The stop-start takes a little getting used to (many factors that influence
whether it will or won't operate, such as aircon, steering angle, gearbox
mode, etc).

Annoyingly it's not fully predictable, e.g. you brake to a stop, the
engine stops, the hold-assist on the brakes kicks in (saving you from
having to apply the parking brake while preventing brake lights from
annoying the car behind) when you take your foot off the brake *sometimes*
the engine will restart immediately, surely it could have worked out
before stopping that it would need to restart, and not bothered stopping?

Our Honda has stop-start which can be turned off if you want. I hadn't
realised it doesn't always use the starter motor to restart - maybe that's
model-dependant, because it sounds exactly the same noise as when the car is
started on the key.

If the alternator is capable of starting the car why don't they just remove
the starter motor and save the cost and weight?

wrote:

NY wrote:

Our Honda has stop-start which can be turned off if you want.

This can be disabled temporarily, and I gather VCDS can reverse the
switch so it defaults to off and you can enable it when required.

I hadn't realised it doesn't always use the starter motor to
restart - maybe that's model-dependant, because it sounds exactly
the same noise as when the car is started on the key.

If the alternator is capable of starting the car why don't they just remove
the starter motor and save the cost and weight?

Because the oil viscosity when cold means the alternator couldn't
(always) manage it. The alternator does start it very quickly when it's
warm.

It does "light hybrid" jiggery-pokery, which I assume amounts to not
recharging the battery immediately after a start, but recuperating the
energy later when coasting or braking. I don't think it ever uses the
alternator to provide drive to the wheels.

On 24/07/18 09:44, Dave Liquorice wrote:
On Tue, 24 Jul 2018 00:14:28 +0100, Dave Plowman (News) wrote:

But why would you bother when it's simple to just turn off the
ignition?

'cause a diesel, burning it's own oil, will just carry on switched
off or not... B-)

Surely the important thing is to get the car to a standstill as
safely as possible?

So just use the foot brake a bit harder than normal to bring both
car and engine to a safe and controlled standstill.

Some people talk or behave as though the foot brake is some incredibly
delicate system that will break if the pedal is pressed down hard.

The orginal start of this thread was based in the US. They mostly
drive automatics over there so the pigging thing will change down to
counter act the braking. Selecting N still doesn't strike me as
"right" though, selecting the highest fixed drive and braking ought
to work. Assuming the auto box and/or computers will allow that
change to happen with the engine under full throttle.

Given that the accelerator pedal now only operates a potentiometer and
autos don't bring mechanical connections to the driver, there is no easy
way of knowing what a "stuck throttle" fault is and how things are going
to respond to the driver's random fiddling. The foot brake is a known
quantity and the only system with sufficient independence.

"TMS320" wrote in message
news
Given that the accelerator pedal now only operates a potentiometer and
autos don't bring mechanical connections to the driver, there is no easy
way of knowing what a "stuck throttle" fault is and how things are going
to respond to the driver's random fiddling. The foot brake is a known
quantity and the only system with sufficient independence.

The footbrake will also (hopefully!) cancel cruise control. Being cynical,
that is one cause of supposedly "stuck throttle" :-)

On Tue, 24 Jul 2018 12:23:33 +0100
Tim Streater wrote:
In article , wrote:
If the alternator is capable of starting the car why don't they just remove
the starter motor and save the cost and weight?

Which is what our Auris hybrid does.

Something that occurs to me is that being AC alternators will need an inverter
to crank them whereas a starter motor is DC and just needs a circuit to the
battery. I wonder if inverter limitations are what prevents it being used all
the time on non hybrid cars?

"Tim Streater" wrote in message
.. .
If the alternator is capable of starting the car why don't they just
remove
the starter motor and save the cost and weight?

Which is what our Auris hybrid does.

Ah I didn't realise the Auris uses the alternator to start the car from
cold. I presume if the fan belt breaks you are utterly buggered because you
can't restart the engine (if it's stopped) to be able to drive (with the
engine using on battery rather than alternator power for its spark) to a
safe place to wait for Mr RAC or Ms AA to tow you to a garage.

On 24/07/18 10:12, NY wrote:

Braking the engine when it is transmitting power to the wheels will lead
to a "fight" between brakes and engine, with the risk that the energy
that the engine is generating will heat up brakes too much. If you have
an engine generating maybe 100 hp, you've got to dissipate that sort of
energy in the brakes.

That is why you would press ~hard~ and sustain.

What is the effect of the discs heating up
dramatically: can it cause loss of braking force? They did mention
something about "burning out the brakes" which was the reason for
contemplating using the "emergency brake" instead, as if that magically
used different pads and wouldn't be affected in exactly the same way by
brake heating.

Normally the brakes only disperse kinetic and potential energy which are
inherently limited so it usually doesn't matter how you load them.
Against the engine, cautious braking allows the engine to keep the
energy topped up. Also, if your delay allows the speed to rise you've
created a bigger problem than you had to start with.

"Tim Streater" wrote in message
.. .
In article , NY
wrote:

"Tim Streater" wrote in message
...
If the alternator is capable of starting the car why don't they just
remove the starter motor and save the cost and weight?

Which is what our Auris hybrid does.

Ah I didn't realise the Auris uses the alternator to start the car from
cold. I presume if the fan belt breaks you are utterly buggered because
you can't restart the engine (if it's stopped) to be able to drive (with
the engine using on battery rather than alternator power for its spark) to
a safe place to wait for Mr RAC or Ms AA to tow you to a garage.

It doesn't have a traditional alternator.

You could look here for more details:

https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

according to which:

The HSD system replaces the geared transmission, alternator, and
starter motor with:

€¢ MG1, an AC motor-generator having a permanent magnet rotor,
used as a motor when starting the ICE and as a generator (alternator)
when charging the high voltage battery

€¢ MG2, an AC motor-generator, also having a permanent magnet
rotor, used as the primary drive motor and as a generator (alternator),
which regeneration power is directed to the high voltage battery

Ah so the "alternator" and "starter motor" functions are combined with the
motor for actually driving the car. So there's a mechanical connection
between it and the engine (as for a conventional starter motor) so no need
for belt drive. I can't work out from the Wikipedia article: is it
effectively built into the flywheel?

My parents have a hybrid Auris and they are very pleased with it. I noticed
that like a lot of cars with CVT (*), the engine runs *very* fast (a lot
faster than the most efficient speed of 1500 to 2000 rpm that the article
mentions) and for a lot longer than a driver of a manual car would choose to
do, or a conventional auto would except in kickdown mode, before "changing
up". I suppose it knows what it's doing...

(*) The old Dafs and the Volvo 343.

NY wrote:

My parents have a hybrid Auris and they are very pleased with it.

Neighbour had a "normal" prius, now has a prius PHEV, probably works
well for them, lot so short local journeys, so generally plugged-in and
recharged rather than filling the tank.

I noticed that like a lot of cars with CVT (*), the engine runs
*very* fast (a lot faster than the most efficient speed of 1500 to
2000 rpm that the article mentions) and for a lot longer than a
driver of a manual car would choose to do

They don't have Otto cycle engine, instead Atkinson cycle engine, which
is more efficient though less powerful.

In article ,
NY wrote:
What I have noticed with this car is that there is a horrendous about of
slack in the handbrake mechanism. If I brake to a halt on a gradient,
apply the handbrake and then release the footbrake, the car lurches
forwards or backwards (depending on gradient) before coming to a very
sudden stop. It feels like a lot of play, but it may only be an inch or
so of rotation.

Usually caused by wind up in the suspension, so nothing really to do with
the handbrake as such. If you had pure wishbone suspension with the
wishbones at right angles, it wouldn't happen. But most are usually angled
to a semi trailing design. To prevent plunge etc when braking.

--
*Change is inevitable, except from a vending machine.

Dave Plowman London SW
To e-mail, change noise into sound.

"Andy Burns" wrote in message
...
NY wrote:
I noticed that like a lot of cars with CVT (*), the engine runs
*very* fast (a lot faster than the most efficient speed of 1500 to
2000 rpm that the article mentions) and for a lot longer than a
driver of a manual car would choose to do

They don't have Otto cycle engine, instead Atkinson cycle engine, which is
more efficient though less powerful.

So the Auris doesn't actually have a conventional (Otto) petrol engine.
Never knew that. I'll have to Google what the differences are.

In article ,
Andy Burns wrote:
They don't have Otto cycle engine, instead Atkinson cycle engine, which
is more efficient though less powerful.

It's an interesting one. Like most hybrids, the IC engine does all the
work when at speed on a long journey. And an Atkinson cycle type is best
at a constant speed. Efficiency takes a dive outside this. Very noticeable
on early Prius which were very heavy on fuel when cruised at speed.

--
*60-year-old, one owner - needs parts, make offer

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Andy Burns wrote:
They don't have Otto cycle engine, instead Atkinson cycle engine, which
is more efficient though less powerful.

It's an interesting one. Like most hybrids, the IC engine does all the
work when at speed on a long journey. And an Atkinson cycle type is best
at a constant speed. Efficiency takes a dive outside this. Very noticeable
on early Prius which were very heavy on fuel when cruised at speed.

I was surprised at how little battery storage the Auris has (and this may be
true of other hybrids too), so it only uses the motor for a small amount of
the duty cycle - maybe a little bit more for lower speeds that you'd find in
town, so it would keep the towns cleaner at the expense of more pollution in
the countryside or on longer, faster journeys when the IUC engine also
charges the battery.

It sounds a good idea: design an engine that is as efficient as possible at
one speed, and then develop transmission that tries to maintain this engine
speed for a wide range of road speeds.

Are there any hybrids which are purely IC-electric (like diesel-electric
trains) where there is no mechanical connection between IC and wheels, just
a generator and electric motors. This would allow all the smoothness of
acceleration that you get with an electric motor, because the ratio between
motor and wheels is fixed (maybe 1:1), so there are no losses in a fluid
flywheel or in the belts of a CVT. On the other hand,
petrol-electric-kinetic is more energy conversions so there may be extra
losses in that.

At first, I assumed that a petrol/diesel-electric hybrid was like this: no
mechanical connection, only an electric one.

On Tue, 24 Jul 2018 14:46:03 +0100
"NY" wrote:
Are there any hybrids which are purely IC-electric (like diesel-electric
trains) where there is no mechanical connection between IC and wheels, just

Chrevrolet Volt IIRC.

In article ,
NY wrote:
It sounds a good idea: design an engine that is as efficient as possible
at one speed, and then develop transmission that tries to maintain this
engine speed for a wide range of road speeds.

But it's not just engine speed but the load on it. At the end of the day
you need enough 'power' from the combination of IC and electric unit to
maintain its maximum cruising speed. With likely quite a bit in reserve to
climb hills without slowing down considerably.

It's why hybrids tend to give good MPG figures when driven gently. But
often worse than a conventional vehicle when driven fast.

--
*IF A PARSLEY FARMER IS SUED, CAN THEY GARNISH HIS WAGES?

Dave Plowman London SW
To e-mail, change noise into sound.

On 24/07/2018 12:40, NY wrote:
"Tim Streater" wrote in message
.. .
If the alternator is capable of starting the car why don't they just
remove
the starter motor and save the cost and weight?

Which is what our Auris hybrid does.

Ah I didn't realise the Auris uses the alternator to start the car from
cold. I presume if the fan belt breaks you are utterly buggered because
you can't restart the engine (if it's stopped) to be able to drive (with
the engine using on battery rather than alternator power for its spark)
to a safe place to wait for Mr RAC or Ms AA to tow you to a garage.

Its worse than that on a smart car..
the same belt drives the water pump.
You may start the car and have the belt break and you will only get down
the road before you have to turn the engine off to stop it overheating.
Then you can't restart it.

On Tue, 24 Jul 2018 12:48:25 +0100, TMS320 wrote:

That is why you would press ~hard~ and sustain.

Reminded me, there's something called the "Power Braking Test" or "Stall Speed
Test": Rev up on full throttle against a full brake (only works on an
automatic), note steady-state rpm. Stop after a few seconds lest the torque
converter overheats.

This puts all the mechanical energy output in the torque converter -- another
place to dump the energy when braking a fast-moving car with engine on full
throttle.


Thomas Prufer

On 24/07/2018 14:46, NY wrote:

8

Are there any hybrids which are purely IC-electric (like diesel-electric
trains) where there is no mechanical connection between IC and wheels,
just a generator and electric motors. This would allow all the
smoothness of acceleration that you get with an electric motor, because
the ratio between motor and wheels is fixed (maybe 1:1), so there are no
losses in a fluid flywheel or in the belts of a CVT. On the other hand,
petrol-electric-kinetic is more energy conversions so there may be extra
losses in that.

At first, I assumed that a petrol/diesel-electric hybrid was like this:
no mechanical connection, only an electric one.

I think Vauxhall did one but they don't sell them any more.

On 24/07/18 10:18, Dave Plowman (News) wrote:
In article ,
TMS320 wrote:

But why would you bother when it's simple to just turn off the ignition?
Surely the important thing is to get the car to a standstill as safely as
possible?

Yes, it is important to get the car to a standstill as safely as
possible. Why would you increase your workload to do something unusual
in a moment of stress instead of doing something routine?

Working out that turning off the engine if the throttle has suck open
increases your work load?

The context you snipped was about losing eps.

And it's certainly not natural to apply the brakes while the engine is
pulling hard. Unless a rally driver, etc.

It's not natural for the engine to disobey your foot.