Soarer cont'd from page 20 (12+8)
02 May 2003, 11:20 AM
#62
Would have been more interesting to read if Pepper wasn't being a pain. I think Mycroft gets the point, has had his fun, and now is getting on with life and sensible posts.
Jeez, i never thought I would say something like that?
I never looked into torque converters, but i guess they work a little like a water brake, pump and motor combined into one unit.
Paul
Jeez, i never thought I would say something like that?
I never looked into torque converters, but i guess they work a little like a water brake, pump and motor combined into one unit.
Paul
02 May 2003, 11:39 AM
#63
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Claudius.
The easiest way I can think of describing a fluid coupling is....
Imagine two fans one connected to an engine the other to a gearbox. These sit near each other, face to face inside an enclosure.
Now lets fill the enclosure with fluid.
If the engine turns its fan the fan turns the fluid which in turn drives the gearbox fan and thus transmitts drive.
This is a vast simplification as you can imagine, like saying a turbo is two fans but you get the idea. Factors such as size, blade angles, blade design, fluid viscousity and shear values, amount and pressure of fluid, fluid levels all have an effect on the transmission of power through the coupling.
You need to design the coupling so that it gives enough slip to get away smoothly and allows the engine to get up to a pre determined start up torque. Very hard with car auto's as every pull away is different, the latest electronic autos are better in this respect to early vacuum boxes as they allow constant changes.
Once this is achieved the major principle is to limit heat build up and mechanical loss. Thats why most couplings will lock into direct drive once upto speed, usually thats 3rd gear and above on car autos. When this happens they have direct drive the same as a manual.
I'll just point out that I happen to like auto cars but they are not the performance option.
Cheers
Lee
The easiest way I can think of describing a fluid coupling is....
Imagine two fans one connected to an engine the other to a gearbox. These sit near each other, face to face inside an enclosure.
Now lets fill the enclosure with fluid.
If the engine turns its fan the fan turns the fluid which in turn drives the gearbox fan and thus transmitts drive.
This is a vast simplification as you can imagine, like saying a turbo is two fans but you get the idea. Factors such as size, blade angles, blade design, fluid viscousity and shear values, amount and pressure of fluid, fluid levels all have an effect on the transmission of power through the coupling.
You need to design the coupling so that it gives enough slip to get away smoothly and allows the engine to get up to a pre determined start up torque. Very hard with car auto's as every pull away is different, the latest electronic autos are better in this respect to early vacuum boxes as they allow constant changes.
Once this is achieved the major principle is to limit heat build up and mechanical loss. Thats why most couplings will lock into direct drive once upto speed, usually thats 3rd gear and above on car autos. When this happens they have direct drive the same as a manual.
I'll just point out that I happen to like auto cars but they are not the performance option.
Cheers
Lee
02 May 2003, 11:53 AM
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Power losses in the automatic transmission are inherently larger than those in its manual counterpart
However, this fact is more than balanced by shift programs designed to maintain the engine in the maximum economy range
It'll beat a Diablo then?
02 May 2003, 12:05 PM
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If the shift patterns are optimised for it... yes!
This really is so simple... you have used the twin, separted vane design to illustrate what you are saying and again you failed to 'close the traverse'. If one side, the Engine side or 'turbine' is turning at 600rpm [tick-over] and the other side is has '1st' selected [we'll call that ratio 3:1] then the driven side can turn at a maximum of 600rpm and the output is 200rpm to the wheels... The turbine passes the trans. fluid thru the stator and the drive vanes start to turn, there is a ratio shown on all Autoboxes that tells you at what speed this is optimised for, but that will just complicate things... so one side of the Foettinger is turning at 600rpm the fluid forces the otherside round at anything from zero [brake on] to 600rpm... take your foot off the brake and the car will creep forward... because the vanes on the drive side are now turning at say 0rpm to 60rpm... that is the function of a fluid couple and that is as much a 'gear ratio' as the conventional cogs elsewhere... there are losses... but the torque multiplication is present.
The Foettinger is a 'fluid variable gear' to quote his own patent.
Edited as my first draught was done in 60secs prior to a meeting... and it scanned rather badly.
[Edited by Mycroft - 5/2/2003 1:59:38 PM]
This really is so simple... you have used the twin, separted vane design to illustrate what you are saying and again you failed to 'close the traverse'. If one side, the Engine side or 'turbine' is turning at 600rpm [tick-over] and the other side is has '1st' selected [we'll call that ratio 3:1] then the driven side can turn at a maximum of 600rpm and the output is 200rpm to the wheels... The turbine passes the trans. fluid thru the stator and the drive vanes start to turn, there is a ratio shown on all Autoboxes that tells you at what speed this is optimised for, but that will just complicate things... so one side of the Foettinger is turning at 600rpm the fluid forces the otherside round at anything from zero [brake on] to 600rpm... take your foot off the brake and the car will creep forward... because the vanes on the drive side are now turning at say 0rpm to 60rpm... that is the function of a fluid couple and that is as much a 'gear ratio' as the conventional cogs elsewhere... there are losses... but the torque multiplication is present.
The Foettinger is a 'fluid variable gear' to quote his own patent.
Edited as my first draught was done in 60secs prior to a meeting... and it scanned rather badly.
[Edited by Mycroft - 5/2/2003 1:59:38 PM]
02 May 2003, 02:33 PM
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This guy is is a real Auto'trans guru and this is his site... I met him in the States 10 years ago.
He along with Mike Kluger [who I had met a year or so earlier] are probably the best Auto'box designers/builders in the Western World... Mike Klugers' work was used by Toyota to design the A340E box as fitted to my car...
http://www.rebuilt-automatic-transmissions.com/
Lee, E-mail your thoughts to these guys... better still send them a link to here and the other thread...
He along with Mike Kluger [who I had met a year or so earlier] are probably the best Auto'box designers/builders in the Western World... Mike Klugers' work was used by Toyota to design the A340E box as fitted to my car...
http://www.rebuilt-automatic-transmissions.com/
Lee, E-mail your thoughts to these guys... better still send them a link to here and the other thread...
02 May 2003, 02:52 PM
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I'll do my best here to make things clear. This is me no copy and paste or reading from books just 6 years at uni and 17years experience.
You keep quoting Foettinger, his design did away with the need for draft tubes and the majority of the pipe work needed for fluid couplings making them more efficient, he didn't reinvent the wheel or break the laws of physics.
We buy couplings from a firm called Voith whose products use this principle.
The coupling is sometimes refered to as a variable gear fluid drive as it alters the speed ratio between its input side and outputside. A torque convertor is the same.
How does this help us in practice.
On an Electric Motor with a near linear torque output and coupling its a must. At 0rpm the motor has near zero torque, the coupling will allow the motor to spin up to say 50% (easy figure) at which time it could be producing 70% maximum torque. Perhaps 65% of this torque is transmited through the coupling to the gearbox.
So the gearbox input shaft is turning at 0rpm and with the coupling allowing the motor to spin upto 50% its transmitting 65% of torque to the input side of the gearbox instead of nearly zero. You can see why its refered to as a gear or ratio.
With me? Wonderful things.
The 5% of loss is seen has heat and the couplings need cooling or they would explode. (Which they do from time to time)
Lets get back to the car in Mycrofts example then. No torque figures are quoted so I'll use 300lbft and all figure quoted are to make it easy to understand.
Manual and Auto examples shall use Myrofts 3:1 1st gear ratio.
So Pulling away.
The engine is turning at 600rpm and so is the input to the coupling. The output of the coupling and input of the gearbox are at 0rpm. Release the brakes and the car will creep (In most situations) as a small amount of torque is transmitted through the coupling but at this speed the coupling is designed to slip to allow you to stop in gear.
At 1000rpm the engine may produce around 75 lbft so not very good for a quick get away o the TC will allow the engine to spin up to say 2000 rpm when it will be producing say 200lbft, this will be transmitted to the input side of the gearbox by the TC allowing for losses say 180lbft.
So again the input shaft of the gearbox is at zero and by spinning the engine up to 2000rpm we can get 180lbft instead of 75lbft. A good multiplication factor then.
The Manual gearbox input shaft is at zero and separated from the engine by the clutch. Rev the engine to 2000rpm, drop the clutch and all 200lbft of torque is transmitted to the gearbox input shaft.
The high speed in gear chase then and the engine is on its torque curve. Both manual and Auto cars having same gearbox and diff ratios etc.
Auto.
We have just kicked down and the TC is allowing 1000rpm of slip. the engine is at 4500rpm and is delivering 300lbft of torque. The input side of the gearbox is turning at 3500rpm and is recieving around 275lbft of torque through the coupling, 25lbft losses.
So the input shaft of the gearbox is turning at 3500rpm with 275lbft of torque acting on it.
Manual
We have the same ratio's and are at the same speed so the input shaft on the gearbox is at 3500rpm so the engine, with no clutch slip, has to be turning at 3500rpm. The engine is producing 300lbft of torque and all this is transmitted to the gearbox input shaft.
So the input shaft of the gearbox is turning at 3500rpm with 300lbft of torque acting on it.
As we can see the manual at 3500rpm engine speed puts 25lbft more to the gearbox than the Auto does at 4500rpm engine speed.
Any engineer will now I have vastly simplified this but the basic principles have been explained.
Lee
You keep quoting Foettinger, his design did away with the need for draft tubes and the majority of the pipe work needed for fluid couplings making them more efficient, he didn't reinvent the wheel or break the laws of physics.
We buy couplings from a firm called Voith whose products use this principle.
The coupling is sometimes refered to as a variable gear fluid drive as it alters the speed ratio between its input side and outputside. A torque convertor is the same.
How does this help us in practice.
On an Electric Motor with a near linear torque output and coupling its a must. At 0rpm the motor has near zero torque, the coupling will allow the motor to spin up to say 50% (easy figure) at which time it could be producing 70% maximum torque. Perhaps 65% of this torque is transmited through the coupling to the gearbox.
So the gearbox input shaft is turning at 0rpm and with the coupling allowing the motor to spin upto 50% its transmitting 65% of torque to the input side of the gearbox instead of nearly zero. You can see why its refered to as a gear or ratio.
With me? Wonderful things.
The 5% of loss is seen has heat and the couplings need cooling or they would explode. (Which they do from time to time)
Lets get back to the car in Mycrofts example then. No torque figures are quoted so I'll use 300lbft and all figure quoted are to make it easy to understand.
Manual and Auto examples shall use Myrofts 3:1 1st gear ratio.
So Pulling away.
The engine is turning at 600rpm and so is the input to the coupling. The output of the coupling and input of the gearbox are at 0rpm. Release the brakes and the car will creep (In most situations) as a small amount of torque is transmitted through the coupling but at this speed the coupling is designed to slip to allow you to stop in gear.
At 1000rpm the engine may produce around 75 lbft so not very good for a quick get away o the TC will allow the engine to spin up to say 2000 rpm when it will be producing say 200lbft, this will be transmitted to the input side of the gearbox by the TC allowing for losses say 180lbft.
So again the input shaft of the gearbox is at zero and by spinning the engine up to 2000rpm we can get 180lbft instead of 75lbft. A good multiplication factor then.
The Manual gearbox input shaft is at zero and separated from the engine by the clutch. Rev the engine to 2000rpm, drop the clutch and all 200lbft of torque is transmitted to the gearbox input shaft.
The high speed in gear chase then and the engine is on its torque curve. Both manual and Auto cars having same gearbox and diff ratios etc.
Auto.
We have just kicked down and the TC is allowing 1000rpm of slip. the engine is at 4500rpm and is delivering 300lbft of torque. The input side of the gearbox is turning at 3500rpm and is recieving around 275lbft of torque through the coupling, 25lbft losses.
So the input shaft of the gearbox is turning at 3500rpm with 275lbft of torque acting on it.
Manual
We have the same ratio's and are at the same speed so the input shaft on the gearbox is at 3500rpm so the engine, with no clutch slip, has to be turning at 3500rpm. The engine is producing 300lbft of torque and all this is transmitted to the gearbox input shaft.
So the input shaft of the gearbox is turning at 3500rpm with 300lbft of torque acting on it.
As we can see the manual at 3500rpm engine speed puts 25lbft more to the gearbox than the Auto does at 4500rpm engine speed.
Any engineer will now I have vastly simplified this but the basic principles have been explained.
Lee
02 May 2003, 03:27 PM
#69
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ON TOPIC:
I'm not an engineer by any means, in fact I'm hardly technical at all, but...
If it was that simple (Mycroft), then why don't we all have autoboxes which multiply the torque output of our cars to give us massive power?
Genuine question.
I'm not an engineer by any means, in fact I'm hardly technical at all, but...
If it was that simple (Mycroft), then why don't we all have autoboxes which multiply the torque output of our cars to give us massive power?
Genuine question.
02 May 2003, 03:49 PM
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Which all comes back to my point.
De-coupling engine output and box input shaft via torque convertor allows a level of gearing down.
So it's like changing down a ratio in a manual car / kickdown in an auto box. Nothing more.
So it "multiplies" torque just like changing down a ratio in a manual car, or kickdown in an auto box. Nothing more.
Hence you have no "magic multiplier". Is the Diablo stuck in top gear?
De-coupling engine output and box input shaft via torque convertor allows a level of gearing down.
So it's like changing down a ratio in a manual car / kickdown in an auto box. Nothing more.
So it "multiplies" torque just like changing down a ratio in a manual car, or kickdown in an auto box. Nothing more.
Hence you have no "magic multiplier". Is the Diablo stuck in top gear?
02 May 2003, 03:54 PM
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###
Hence you have no "magic multiplier".
###
I do!, it is called a Foettinger!
The diablo isn't stuck but he has to 'stall' he changes gear and whilst in neutral he has lost power... I never have the power taken from my wheels...
Hence you have no "magic multiplier".
###
I do!, it is called a Foettinger!
The diablo isn't stuck but he has to 'stall' he changes gear and whilst in neutral he has lost power... I never have the power taken from my wheels...
02 May 2003, 04:07 PM
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###
Hence you have no "magic multiplier".
###
I do!, it is called a Foettinger!
The diablo isn't stuck but he has to 'stall', he p*sses himself laughing at the strange bloke in the soarer muttering furiously about foettingers and trying to race him while he's just trying to get home to **** the supermodel in the passenger seat, hence taking his foot off the gas and letting my car pass ... I never have the power taken from my wheels...
Where is the response from the lambo owner on you 'beating ' him?
answer: there isn't one, cos regardless of whether you did indeed beat him or not, he has better things to do with his time.
This is why he drives a diablo, and you do not....
02 May 2003, 04:15 PM
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Mik sorta...
But that is only part of the story, how it works is this, we are following each other... doing 80mph, he goes for the change down his exhaust tells me what he is doing, I am travelling behind at 3000rpm/80mph... I see the tell tale... and in 3/10th of a second my car has 7500rpm on the counter and has changed down s the gear it has selected needs only 4500rpm to do 80mph.. in real terms allowing for losses my power at the wheels has just jumped 50%, and i have 'powered' into that situation and all this time our Lambo driver has been in neutral or playing footsie with the clutch...
He is history... he can power up again and he will have that dynamic to play with and a great driver will hold me... when I had 340hp... now with the power I have even the best gear shifter in the World could catch up... he is limited by his ability and the dynamic he has under foot... I just press to the floor and watch the road...
But that is only part of the story, how it works is this, we are following each other... doing 80mph, he goes for the change down his exhaust tells me what he is doing, I am travelling behind at 3000rpm/80mph... I see the tell tale... and in 3/10th of a second my car has 7500rpm on the counter and has changed down s the gear it has selected needs only 4500rpm to do 80mph.. in real terms allowing for losses my power at the wheels has just jumped 50%, and i have 'powered' into that situation and all this time our Lambo driver has been in neutral or playing footsie with the clutch...
He is history... he can power up again and he will have that dynamic to play with and a great driver will hold me... when I had 340hp... now with the power I have even the best gear shifter in the World could catch up... he is limited by his ability and the dynamic he has under foot... I just press to the floor and watch the road...
02 May 2003, 06:25 PM
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Oh dear,
I was going to consider teaching as a proffession but I can't even get someone to understand one subject.
The torque convertor lifts the engine speed in relation to the gearbox. If the torque is the same at the speed point it lifts from and too there is no difference in torque reaching the box.
If you have found a way do do that please inform the Nobel people.
The very simple way I can explain gearing/torque...
A car has an engine that revs to 5000rpm, torque is 100lbft, it is fitted with a "Super Mycroft Wizzo" torque convertor that alters gearing.
The gearing through all the TC, gearbox and diff allows the car to get to 100mph in top gear with the engine at maximum revs. The overall gearing is thus 20mph per 1000rpm.
Identicle car has an engine that revs to 5000rpm, torque is 100lbft, but is fitted with a manual gearbox and clutch. The gearing through all the clutch, gearbox and diff allows the car to get to 100mph in top gear with the engine at maximum revs. The overall gearing is thus 20mph per 1000rpm.
Both cars will accelerate at the same rate?
Well no as the auto car has coupling losses to contend with so will need more power just to keep up.
As for an auto spooling up the turbo's. Most modern turbo's will be on full boost by mid range anyway and lag isn't a major issue.
But if you say it is the Diablo has 450lbft of torque available from 3500rpm and his throttle response is instant.
Who's to say he isn't in the right gear when your up his ****?
Lee
I was going to consider teaching as a proffession but I can't even get someone to understand one subject.
The torque convertor lifts the engine speed in relation to the gearbox. If the torque is the same at the speed point it lifts from and too there is no difference in torque reaching the box.
If you have found a way do do that please inform the Nobel people.
The very simple way I can explain gearing/torque...
A car has an engine that revs to 5000rpm, torque is 100lbft, it is fitted with a "Super Mycroft Wizzo" torque convertor that alters gearing.
The gearing through all the TC, gearbox and diff allows the car to get to 100mph in top gear with the engine at maximum revs. The overall gearing is thus 20mph per 1000rpm.
Identicle car has an engine that revs to 5000rpm, torque is 100lbft, but is fitted with a manual gearbox and clutch. The gearing through all the clutch, gearbox and diff allows the car to get to 100mph in top gear with the engine at maximum revs. The overall gearing is thus 20mph per 1000rpm.
Both cars will accelerate at the same rate?
Well no as the auto car has coupling losses to contend with so will need more power just to keep up.
As for an auto spooling up the turbo's. Most modern turbo's will be on full boost by mid range anyway and lag isn't a major issue.
But if you say it is the Diablo has 450lbft of torque available from 3500rpm and his throttle response is instant.
Who's to say he isn't in the right gear when your up his ****?
Lee
02 May 2003, 06:31 PM
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I think it was mentioned earlier, but.
If we are to understand that autos are faster than a manual and they magic extra torque I suggest we ring all the performance manufturers, race and rally teams as they are all making a big mistake.
Perhaps they should go to the fluid dynamics night school.
Lee
If we are to understand that autos are faster than a manual and they magic extra torque I suggest we ring all the performance manufturers, race and rally teams as they are all making a big mistake.
Perhaps they should go to the fluid dynamics night school.
Lee
02 May 2003, 07:24 PM
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There are some 'downsides' to having a car set-up like mine...
Most people are ignorant of the fact that Autos are no longer 'all slush-mobiles' slowly the advances made in the last 15-20 years are being recognised... duplexing is the biggest advance, followed by new vane profiles that use the auto fluid better, stator tolerances are now on a par with those ina Turbocharger... the entire thing has changed dramatically since the mid eighties.
The main downside is the slightly strange take-off characteristics that come with the changes I have made... the car can be driven slowly but it is not easy, it wants to fly... it is very 'positive' in its take-off...
Most people are ignorant of the fact that Autos are no longer 'all slush-mobiles' slowly the advances made in the last 15-20 years are being recognised... duplexing is the biggest advance, followed by new vane profiles that use the auto fluid better, stator tolerances are now on a par with those ina Turbocharger... the entire thing has changed dramatically since the mid eighties.
The main downside is the slightly strange take-off characteristics that come with the changes I have made... the car can be driven slowly but it is not easy, it wants to fly... it is very 'positive' in its take-off...
02 May 2003, 07:24 PM
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The Foettinger acts as a torque multiplier... ''it does what it says on the tin''... it multiplies the torque!...
It only increases "multiplies" the torque if the increase in rpm results in an increase in torque.
most people 'out there' would never guess what my car is capable of... until they are dispatched... that is why they are usually in the wrong gear... and not many people will drive an 'Itarion Starion' down the Motorway at 80mph in 3rd, just in case a Toyota Soarer happens along.
PMSL
Lee
02 May 2003, 07:55 PM
#87
Okay, some laws of physics that can't be broken, although I will not point out exactly how this relates to previous posts.
Power out < Power in.
You will always loose some power, and you can never get more powerout than you put in. However, since the output speed is close to zero (or zero if held on the brakes) you can get massive torque at low power (ie a spanner and scaffold pole).
You can get a hydraulic gear ratio.
Put a motor on a hydraulic pump that pumps 1cc/rev. Connect output of pump to hydrualic motor that rotates 1rev/cc. IN effect (yes this a crude example) the gearing is 2:1, but you will have less than double the torque due to losses, shed as heat. I'm just saying it's possible, not how things are in a TC.
What I still am unclear on, is how the TC works exactly, I will have to read some posts more thoroughly, not my cup of tea.
Paul
Power out < Power in.
You will always loose some power, and you can never get more powerout than you put in. However, since the output speed is close to zero (or zero if held on the brakes) you can get massive torque at low power (ie a spanner and scaffold pole).
You can get a hydraulic gear ratio.
Put a motor on a hydraulic pump that pumps 1cc/rev. Connect output of pump to hydrualic motor that rotates 1rev/cc. IN effect (yes this a crude example) the gearing is 2:1, but you will have less than double the torque due to losses, shed as heat. I'm just saying it's possible, not how things are in a TC.
What I still am unclear on, is how the TC works exactly, I will have to read some posts more thoroughly, not my cup of tea.
Paul
02 May 2003, 08:07 PM
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Oh dear, I asked for laws not nebulous examples...
Newtons Laws on Motion, none apply here except to re-inforce what I say...
Early Euclidean 'hydro-dynamics' [] also only re-inforce what I say...
I can't find anything that supports Logiclees' standpoint.
Newtons Laws on Motion, none apply here except to re-inforce what I say...
Early Euclidean 'hydro-dynamics' [
] also only re-inforce what I say...I can't find anything that supports Logiclees' standpoint.
02 May 2003, 08:43 PM
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Look I realy have had enough, I have been on scoobynet a long time and have never had this problem before.
The ratio from the input of the gearbox back doesn't change even with a torque convertor. We are not talking about changing down gears.
So the all important figure is the torque acting on the input side of the gearbox.
A torque convertor allows the engine to increase revs to multiply the torque effect on the gearbox. This is fine on Electric motors and at very low rpm on IC engines. The multiply effect is totally dependent on the output of the engine not the fluid coupling.
When the petrol engine gets on its torque curve an increase in revs means very little difference in torque so similar torque is acting on the input shaft of the gearbox wether the engine is allowed to spin at (Example) 3500 or 4500rpm.
Lee
The ratio from the input of the gearbox back doesn't change even with a torque convertor. We are not talking about changing down gears.
So the all important figure is the torque acting on the input side of the gearbox.
A torque convertor allows the engine to increase revs to multiply the torque effect on the gearbox. This is fine on Electric motors and at very low rpm on IC engines. The multiply effect is totally dependent on the output of the engine not the fluid coupling.
When the petrol engine gets on its torque curve an increase in revs means very little difference in torque so similar torque is acting on the input shaft of the gearbox wether the engine is allowed to spin at (Example) 3500 or 4500rpm.
Lee