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Seamless Gearboxes


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#251 NTSOS

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Posted 04 March 2012 - 16:25

Gerrard,

Since you refuse to accept Grunt's excellent engineering analysis, why in heck don't you contact Bill Martin of Zeroshift and ask him to address your concerns.....he's a good guy and I am sure he would be glad to answer all of your questions about Zeroshift's operating system......or, maybe not! :)

Juanito

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#252 24gerrard

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Posted 04 March 2012 - 18:20

[quote]name='24gerrard' date='Mar 1 2012, 11:34' post='5557931']
Posted Image[/quote]

As Kevin Bloody Wilson would say, 'there's that bloody (door) graph again.
Now all you guys taking the p--s are reasonable engineers.
I would guess you mostly drive fancy cars with manual gearboxes and rev counters.
Meets the image I suppose.
OK, so here is your first applied transmission engineering test.

Start your engines (thats usualy a key you have to turn).
Engage first gear and drive off.
I will let you work the clutch and gear lever I expect you were all taught that by your instructor.

Now find a strait flat piece of road with no traffic. (not easy)
Drive your wonderful machines with 1000rpm on the rev counter in top gear.
I specify 1000 rpm because it makes it easier but you can choose any rpm you like, or any gear for that matter.

Now here is the test.
Very gradualy press down on the clutch pedal (thats the one on the left) until the engine rpm climbes to 2400 rpm.
You will be forced to reduce the throttle you have applied to stop engine runaway.
Keep the clutch pedal exactly at this position.
Carefuly apply the handbrake gently until the car stops.

Now try telling me that a 1400 rpm difference between the engine revs and the input shaft revs is NOT a F==CK--G disengagement.
You can now try SLIPPING the clutch with 1400 rpm difference and see how far you get.

On the graph where the engine revs depart from the input shaft rpm. the propshaft torque takes an almost vertical decent.
If the clutch was capable of SLIPPING which it is not, the torque reading would increase. Actualy the geartrain would probably explode but hell so what.
THERE IS NO TORQUE BEING TRANSFERED FROM INPUT TO OUTPUT IN THIS GEARBOX AT SHIFT OVERLAP.
There is NO input torque at this point.
Because of this the output components have NO stationary reference.

Edited by 24gerrard, 04 March 2012 - 18:22.


#253 cheapracer

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Posted 04 March 2012 - 19:03

Start your engines (thats usualy a key you have to turn).


Yup, did that ....



Engage first gear and drive off.


Yup, pulled out the driveway and now underway in first gear up the street ...



I will let you work the clutch and gear lever I expect you were all taught that by your instructor.


Clutch? Oh, can't do, it's an auto.

#254 Tony Matthews

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Posted 04 March 2012 - 19:09

Who's been feeding the troll?

#255 24gerrard

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Posted 04 March 2012 - 19:13

Never mind Cheapy send it to me and I will replace the torque converter with a clutch and increase the performance for you.
With the planetary geartrain you have there is of course no gap in torque delivery during the shifts.
Thats because there is no layshaft.
If it is one of those dual layshaft/clutch auto shift things I can only suggest you buy something that is not dragging so much weight and torque loss around with it.
Surely your sports car with all your clever suspension etc will have a super duper all singing all dancing layshaft gearbox.

Edited by 24gerrard, 04 March 2012 - 21:34.


#256 24gerrard

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Posted 04 March 2012 - 19:48

Who's been feeding the troll?


Whats up Tony?
Nothing to add?
Your picture of swans with their heads under water would have been a better comment.
Sorry just trying to help.

#257 Charles E Taylor

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Posted 04 March 2012 - 20:17

I have watched this debate with interest.

There is, a lot of emphasis on semantics.



But, to add to the fire.........




I would like to know.

How it is possible to drive 2 Gears at full Power (Torque X Speed) which are splined (Locked) to an infinitely stiff common shaft - at 2 distinctly different speeds - at the same time?


Sorry.......maybe really sorry!



Charlie


#258 24gerrard

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Posted 04 March 2012 - 21:22

I have watched this debate with interest.

There is, a lot of emphasis on semantics.



But, to add to the fire.........




I would like to know.

How it is possible to drive 2 Gears at full Power (Torque X Speed) which are splined (Locked) to an infinitely stiff common shaft - at 2 distinctly different speeds - at the same time?


Sorry.......maybe really sorry!



Charlie


Your on the right lines Charlie but it is not the gears that are splined to the output shaft, it is the hub that carries the gearshift baulking assemblies.
The gears are free to rotate on the output shaft.
However they are both constantly in mesh with the laygear, so they certainly do rotate at different speeds.

I would not describe the thread as about semantics.
There are two words used to describe these layshaft gearboxes with smoothed out rapid shifts, zeroshift and seamless.
I consider these names to be misleading when used to describe the operation of the shift mechanism.

This is based on the ongoing discusion (argument) as to whether there is a 'gap' in the transfer of torque from input to output during the shift.
If I am correct, it will prove that all the modifications and new ideas in shift mechanisms for layshaft gearboxes since the original dog ring manual gearboxes have not increased the shift overlap speeds and the mechanisms although very clever, have only reduced wear and breakages in the units and the finer control over the components using the latest electronics has simply smoothed the shift and helped reduce wear.
The layshaft gearbox remains a concept from the 1890's with little improvement since then.

Edited by 24gerrard, 04 March 2012 - 21:23.


#259 gruntguru

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Posted 04 March 2012 - 23:00

How it is possible to drive 2 Gears at full Power (Torque X Speed) which are splined (Locked) to an infinitely stiff common shaft - at 2 distinctly different speeds - at the same time?

In the case of a Zeroshift box, the lower gear has an overrun "ratchet" equivalent, in which the dogs are automatically disengaged the instant the gear begins to overrun. That's how.

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#260 gruntguru

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Posted 04 March 2012 - 23:08

Start your engines (thats usualy a key you have to turn).
Engage first gear and drive off.
I will let you work the clutch and gear lever I expect you were all taught that by your instructor.

Now find a strait flat piece of road with no traffic. (not easy)
Drive your wonderful machines with 1000rpm on the rev counter in top gear.
I specify 1000 rpm because it makes it easier but you can choose any rpm you like, or any gear for that matter.

Now here is the test.
Very gradualy press down on the clutch pedal (thats the one on the left) until the engine rpm climbes to 2400 rpm.
You will be forced to reduce the throttle you have applied to stop engine runaway.
Keep the clutch pedal exactly at this position.
Carefuly apply the handbrake gently until the car stops.

Yep. Here's what happened. When the revs got to 2400 I let the clutch pedal out a smidge and the revs started to drop. So I pushed down the accelerator until the revs started to rise again. I kept doing this until the accelerator was all the way down and I was modulating the clutch to keep the revs at 2400. I had maximum engine torque going down the driveline with the clutch slipping!!!

So that's how Zeroshift are doing it! Those tricky bastards.

#261 bigleagueslider

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Posted 05 March 2012 - 04:39

In the case of a Zeroshift box, the lower gear has an overrun "ratchet" equivalent, in which the dogs are automatically disengaged the instant the gear begins to overrun. That's how.


Regrading Zeroshift, gruntguru is correct. The shift dogs are basically ratchet devices. As the selected gear overruns the current gear, the selected gear ratchets engage and the current gear ratchets are "kicked" free. This all happens within a fraction of a single gear rotation. It's not instantaneous, but it does happen quite quickly.

Since the system works by having one gear overrun another, there are never two gears driving at the same time.


#262 gruntguru

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Posted 05 March 2012 - 06:03

Since the system works by having one gear overrun another, there are never two gears driving at the same time.

Well - there are actually.

Due to elasticity in the system there is a "handover" period (very brief) where the load in the new gear is increasing while the load in the old gear is decreasing.

#263 24gerrard

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Posted 05 March 2012 - 09:22

Yep. Here's what happened. When the revs got to 2400 I let the clutch pedal out a smidge and the revs started to drop. So I pushed down the accelerator until the revs started to rise again. I kept doing this until the accelerator was all the way down and I was modulating the clutch to keep the revs at 2400. I had maximum engine torque going down the driveline with the clutch slipping!!!

So that's how Zeroshift are doing it! Those tricky bastards.


I suggest you try again.
It is possible to slip a clutch to around a 500 rpm difference but NO WAY with 1400 rpm difference.
Even a torque converter (which I used to repair and balance) have stall values (slip between input to output) of around 1200 rpm and that is slip in a fluid.

I challenge anyone out there to do it and find me a friction material capable of it.
A 1400 rpm difference between input and output is a disengagement.

#264 24gerrard

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Posted 05 March 2012 - 09:25

Well - there are actually.

Due to elasticity in the system there is a "handover" period (very brief) where the load in the new gear is increasing while the load in the old gear is decreasing.


What he means is that during the shift NO torque is passed between the input and the output of the gearbox and the engine has its torque output cut.

#265 24gerrard

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Posted 05 March 2012 - 09:31

Last year exhaust blown diffusers in F1 allowed modulation of engine torque output from the engine.
This gave a high mass of exhaust gas to blow the diffusers.
It was also a convenient way to trick the regulations on traction limiting through corners.

This year no EBD, seamless shift gearboxes that also need high modulation of the shifts is this years convenient way to achieve traction limiting.
THIS is why it is essential for them to cover any gap in the input to output torque in these gearboxes so as to cover up any program for TL.
Let everyone know there is a gap and it becomes obvious.

#266 GeoffR

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Posted 05 March 2012 - 09:45

I think we should let him carry on talking to himself

This has become SO boring, so +1!


#267 24gerrard

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Posted 05 March 2012 - 10:09

This has become SO boring, so +1!


Nothing to add.
Please yourself of course.


#268 24gerrard

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Posted 05 March 2012 - 10:20

I had maximum engine torque going down the driveline with the clutch slipping!!!


So why does the torque trace for the propshaft go DOWN at this point!!!!!!!!!!!!!!?
If you could slip at a 1400rpm difference and it is this that happens on the zeroshift graph, WHY DOESNT THE TORQUE INCREASE!!!?
Dont tell me because the engine torque is modulated, YOU JUST TOLD ME YOU INCREASED THE THROTTLE POSITION!!!!
Of course the engine torque (and rpm) is modulated on the graph, it has to be to prevent the engine over reving through the disengagement.

Edited by 24gerrard, 05 March 2012 - 10:21.


#269 cheapracer

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Posted 05 March 2012 - 10:42

This has become SO boring, so +1!


You ruined a full house .. :lol:

#270 cheapracer

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Posted 05 March 2012 - 11:07

It is possible to slip a clutch to around a 500 rpm difference but NO WAY with 1400 rpm difference.
I challenge anyone out there to do it and find me a friction material capable of it.


Err, clutch lining?

A billion cars every day take off multiple times at well above 1400rpm by way of balancing clutch slippage.



Even a torque converter (which I used to repair and balance) have stall values (slip between input to output) of around 1200 rpm and that is slip in a fluid.


A torque converter's stall speed totally depends on the weight and rpm torque peak point of a car and nowadays they are more likely to be in the 1500 to 1800 rpm area. TQ's are available generally up to 3000rpm stall 'over the counter' at any Speed Shop with 2500rpm being a quite common performance option.






#271 24gerrard

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Posted 05 March 2012 - 11:57

Err, clutch lining?

A billion cars every day take off multiple times at well above 1400rpm by way of balancing clutch slippage.

A torque converter's stall speed totally depends on the weight and rpm torque peak point of a car and nowadays they are more likely to be in the 1500 to 1800 rpm area. TQ's are available generally up to 3000rpm stall 'over the counter' at any Speed Shop with 2500rpm being a quite common performance option.


Cars take off with a rapidly diminishing rpm difference between the engine flywheel and the clutch cover disk.
The torque at the propshaft increases during take off, it does not diminish as in the graph.
Taking off is not balancing clutch slip it is controlling the rate of clutch engagement against tyre traction and engine torque.

Competition torque converters can indeed be bought over the counter with stall speeds over 2500 rpm I have built them.
That high a stall speed is suitable only for high acceleration not general use.
(nowhere near a balance close to one to one between turbine and impellor through such a high stall stator (with sprag) can be achieved for cruise)
This is fluid slip which is far easier to achieve than with solid friction material.
With 2500 rpm stall a transmission system with a converter at this high level of stall will require a lock up clutch in the converter for it to be in any way roadable.
It will also heat up the oil very rapidly and will require extra transmission oil cooling to prevent the oil boiling.
1500 to 1800 rpm stall for a road torque converter is only practical with a lock up clutch.
Any attempt to slip solid friction material with full power from a high performance engine will burn out the clutch in a very short time.


#272 24gerrard

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Posted 05 March 2012 - 14:28

Come on Cheapy and Grunt, if the clutch is being slipped with full power on the zeroshift graph.
WHY IS THE TORQUE AT THE PROPSHAFT GOING DOWN!!!?

#273 cheapracer

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Posted 05 March 2012 - 15:04

WHY IS THE TORQUE AT THE PROPSHAFT GOING DOWN!!!?


Random typical gearbox;

1st gear = 3.2:1
2nd gear = 2.2:1

Engine torque = 100ftlbs

Therefore;

I'm driving down the road in 1st gear with my 320ftlbs of torque and then I change to 2nd gear and I go down to 220ftlbs of torque.

This is why we do not take off from traffic lights in 4th gear.




#274 NTSOS

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Posted 05 March 2012 - 17:02

Random typical gearbox;

1st gear = 3.2:1
2nd gear = 2.2:1

Engine torque = 100ftlbs

Therefore;

I'm driving down the road in 1st gear with my 320ftlbs of torque and then I change to 2nd gear and I go down to 220ftlbs of torque.

This is why we do not take off from traffic lights in 4th gear.


I know, this is nuts......the graph simply and clearly shows the torque dropping down to 2nd gear level after the shift is completed.....in a few milliseconds I might add!

There is no torque flow gap, there is no torque flow interruption, none, zero, nada!

On another note, the easiest way to demonstrate what exactly the clutch is doing:

1. Depress clutch when vehicle is stationary.

2. Take engine to 1400 RPM.

3. Gently release clutch pedal.

4. The car will launch!

There is output torque during the shift, there is no torque flow gap, there is no torque flow interruption, none, zero, nada!

John

#275 24gerrard

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Posted 05 March 2012 - 17:02

Random typical gearbox;

1st gear = 3.2:1
2nd gear = 2.2:1

Engine torque = 100ftlbs

Therefore;

I'm driving down the road in 1st gear with my 320ftlbs of torque and then I change to 2nd gear and I go down to 220ftlbs of torque.

This is why we do not take off from traffic lights in 4th gear.


You have done it again Cheapy you have forgotten your clutch slip.
Ruins the love life.
You should add the middle part of the graph and stop just relying on each end of it and guess work.

#276 24gerrard

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Posted 05 March 2012 - 17:04

I know, this is nuts......the graph simply and clearly shows the torque dropping down to 2nd gear level after the shift is completed.....in a few milliseconds I might add!

There is no torque flow gap, there is no torque flow interruption, none, zero, nada!

On another note, the easiest way to demonstrate what exactly the clutch is doing:

1. Depress clutch when vehicle is stationary.

2. Take engine to 1400 RPM.

3. Gently release clutch pedal.

4. The car will launch!

There is output torque during the shift, there is no torque flow gap, there is no torque flow interruption, none, zero, nada!

John


Stop looking at the torque trace and believing it is engine torque like they want you to.
It is propshaft torque.

#277 NTSOS

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Posted 05 March 2012 - 17:29

Stop looking at the torque trace and believing it is engine torque like they want you to.
It is propshaft torque.


That is what I said, its the only torque trace on the graph!

John


#278 cheapracer

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Posted 05 March 2012 - 18:23

and guess work.


Nope, simply torque multiplication 101 (speed changer), one of the most basics of engineering next to leverage, radius, etc.






#279 cheapracer

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Posted 05 March 2012 - 18:25

I know, this is nuts......


I was having a good laugh but I'm bored with it again .... oh look, some grass is growing, gotta run!


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#280 NTSOS

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Posted 05 March 2012 - 20:09

I was having a good laugh but I'm bored with it again .... oh look, some grass is growing, gotta run!


Not so fast......we need photos! :up:

John

#281 Tony Matthews

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Posted 05 March 2012 - 22:25

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#282 NTSOS

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Posted 05 March 2012 - 22:44

There you go Tony.....I wonder what the legal status of that stuff is in China?

#283 gruntguru

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Posted 05 March 2012 - 23:18

I suggest you try again.
It is possible to slip a clutch to around a 500 rpm difference but NO WAY with 1400 rpm difference.

No need. I did it once - I can do it again. If I can do it at full throttle, Zeroshift can do it at part throttle. Your understanding of transmissions is apalling!

The Zeroshift graph is a part throttle shift. At full throttle they would slip the clutch less and be content with a harsher, "performance" shift (like your Mini but less harsh).

Edited by gruntguru, 05 March 2012 - 23:19.


#284 gruntguru

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Posted 05 March 2012 - 23:31

So why does the torque trace for the propshaft go DOWN at this point!!!!!!!!!!!!!!?
If you could slip at a 1400rpm difference and it is this that happens on the zeroshift graph, WHY DOESNT THE TORQUE INCREASE!!!?

The torque you see on the graph during the "clutch slipping" phase, is controlled entirely by modulating the clutch. If you knew anything about transmissions you would know that varying the throttle while the clutch is slipping has NO EFFECT ON TORQUE! All that will happen is the rpm will rise or fall.

Dont tell me because the engine torque is modulated, YOU JUST TOLD ME YOU INCREASED THE THROTTLE POSITION!!!!

If you knew anything about transmissions you would know that varying the throttle while the clutch is slipping has NO EFFECT ON TORQUE! All that will happen is the rpm will rise or fall. And yes - the throttle is modulated. Just because I used full throttle to prove a point doesn't mean I think Zeroshift use full throttle during a PART LOAD SHIFT. You haven't really ever worked in the transmission field have you?

Of course the engine torque (and rpm) is modulated on the graph, it has to be to prevent the engine over reving through the disengagement.

Correct. Hmmm I think I have misjudged you. Maybe you read a book on transmissions once? Or perhaps you drove a car once?

#285 pugfan

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Posted 05 March 2012 - 23:43

I am at the top of a ladder, my brother is on the ground and passes me a box of junk to put in the roof.

24gerrard; According to you, this is an impossibility.

#286 desmo

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Posted 06 March 2012 - 01:36

There you go Tony.....I wonder what the legal status of that stuff is in China?


Common roadside weed/commonly grown oil-seed crop. A Chinese girl I knew said they call it "old people's weed" because only old people with joint pain use it there. It's supposed to help with arthritis or something according to traditional Chinese medicine.


#287 NTSOS

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Posted 06 March 2012 - 01:49

Common roadside weed/commonly grown oil-seed crop. A Chinese girl I knew said they call it "old people's weed" because only old people with joint pain use it there. It's supposed to help with arthritis or something according to traditional Chinese medicine.


Let's see, I'm old, I have joint pain....I might like the place! :)

Thanks for that!

John

#288 cheapracer

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Posted 06 March 2012 - 04:38

There you go Tony.....I wonder what the legal status of that stuff is in China?


Zero shift err, I mean zero tolerance for drugs.

But then a policeman would actually have to be interested.


#289 desmo

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Posted 06 March 2012 - 05:32

Yes technically highly illegal, but the authorities absolutely don't care about it growing everywhere or if old people grow a few plants for arthritis medicine and my source said where she was from every little village had a patch for the elderly to use. Plus thousands of hectares are freely grown by farmers for its valuable seed.

This thread can't be hijacked fast enough anyway.

#290 Tony Matthews

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Posted 06 March 2012 - 08:24

I have joint pain....

Is that the same as spliff itch?

#291 24gerrard

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Posted 06 March 2012 - 11:02

I know, this is nuts......the graph simply and clearly shows the torque dropping down to 2nd gear level after the shift is completed.....in a few milliseconds I might add!

There is no torque flow gap, there is no torque flow interruption, none, zero, nada!

On another note, the easiest way to demonstrate what exactly the clutch is doing:

1. Depress clutch when vehicle is stationary.

2. Take engine to 1400 RPM.

3. Gently release clutch pedal.

4. The car will launch!

There is output torque during the shift, there is no torque flow gap, there is no torque flow interruption, none, zero, nada!

John


No, what is shown on the graph is not what the clutch or the torque is doing on take off.
When you release the clutch in a vehicle from stationary with 1400 rpm from the engine the clutch is rapidly engageing it is not stationary holding a slip condition.
On take off as the clutch 'bites' torque increases at the propshaft to the rear wheels to drive the car.
So why does the torque drop on the graph shown as the clutch disengages on this 'zeroshift graph'?
This would not be the case if it were transfering torque through the powertrain as you say.
Is it caused by the clutch disengaging and breaking torque flow, the bullets disengageing from the low gear because the torque has come off the bullets, or is it a combination of the two with the added control to reduce engine rpm.

Dont tell me it is the high gear bullets transfering torque, that happens at the end of the shift overlap and in anycase the torque is dropping at the propshaft torque trace for almost all of the shift time shown.
When the high gear bullets do fully engage and torque begins to be applied as the clutch re-engages and the engine control permits, the torque does indeed level off at the new ratio level and the output shows a return to vehicle acceleration.
The vehicle does not accelerate through the shift, so it is in no way a power on shift, it cant be.
If you are trying to say it is a reduced torque shift, then ask yourself why is it neccessary to reduce torque and where?
If your answer is at the shift baulking bullets, then you are all contradicting youselves.
Show me an engine torque trace for this shift and a torque reading at input and output of the shift engageing mechanism.
To reiterate grunt, if there is a disengagement of the clutch, then there is no stationary reference and all your math is dynamic.

Edited by 24gerrard, 06 March 2012 - 11:33.


#292 24gerrard

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Posted 06 March 2012 - 11:42

Yes technically highly illegal, but the authorities absolutely don't care about it growing everywhere or if old people grow a few plants for arthritis medicine and my source said where she was from every little village had a patch for the elderly to use. Plus thousands of hectares are freely grown by farmers for its valuable seed.

This thread can't be hijacked fast enough anyway.


You can still buy Nigerian Black in Lagos better than this rubbish, my old friend Fella used to grow acres of the stuff and process it. I saw it all with Ginger Baker in 1976.
Of course you children dont realy have a clue do you.
So rabbit on in your self made illusion desmo, you wont experience life as it used to be, not in this mamby pamby era.

#293 24gerrard

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Posted 06 March 2012 - 11:45

I am at the top of a ladder, my brother is on the ground and passes me a box of junk to put in the roof.

24gerrard; According to you, this is an impossibility.


Go back to sleep.

#294 24gerrard

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Posted 06 March 2012 - 11:50

No need. I did it once - I can do it again. If I can do it at full throttle, Zeroshift can do it at part throttle. Your understanding of transmissions is apalling!

The Zeroshift graph is a part throttle shift. At full throttle they would slip the clutch less and be content with a harsher, "performance" shift (like your Mini but less harsh).


Anybody can slip a clutch at full throttle (even modern mamby pambys) with any rpm as long as it exceeds the stall point, means absolutely nothing.
Accept that is that TORQUE is being transfered AND WILL BE READ AT THE PROPSHAFT.
With a 1400 rpm difference on a trailing throttle with reducing torque it AINT POSSIBLE.

My Mini used a bevel epicyclic geartrain with internal clutches and bands, it is simple to achieve a full throttle shift overlap with such a geartrain.
It is not possible with a layshaft stepped gearbox.

Edited by 24gerrard, 06 March 2012 - 11:52.


#295 Fondles

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Posted 06 March 2012 - 12:55

From memory, the Zeroshift gearbox has an electronic link with the engine's ECU and they pull the spark timing back during a shift.
That would explain any torque drop from the engine around the shift period.

Please, make all this stop, it's really unnecessary.

#296 NTSOS

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Posted 06 March 2012 - 13:48

No, what is shown on the graph is not what the clutch or the torque is doing on take off.


Ummm, Gerrard.....no, not talking about take off as it relates to the graph.....the clutch example simply illustrates an easy way to understand the graph's uninterrupted torque flow whilst "slipping" during the Zeroshifts millisecond 1st to 2nd gear change! If it wasn't for the slip and damper I think there would be a spike and then a drop to 2nd gear level torque........depending of course on the software instructions that control the fly by wire clutch etc. and determines the shape of the desired shift trace for that particular situation!

There is no torque flow interruption or gap!

John

Edited by NTSOS, 06 March 2012 - 16:33.


#297 24gerrard

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Posted 06 March 2012 - 21:05

From memory, the Zeroshift gearbox has an electronic link with the engine's ECU and they pull the spark timing back during a shift.
That would explain any torque drop from the engine around the shift period.

Please, make all this stop, it's really unnecessary.


I know reality and the truth are difficult to take these days, so few people use them but stay with it I think you will see it in the end.

You are correct the electronic control system does indeed vary the engine settings to reduce the torque going through the shift mechanism.

SO IT IS NOT A POWER ON SHIFT THEN IS IT?

If it is possible to transfer full torque through the shift components, WHY IS CONTROL NEEDED TO REDUCE ENGINE TORQUE DURING A NON POWER ON SHIFT?

Why not just use the 'clever' shift mechanism that can change the ratios under full load. :rolleyes:
Answer is because the mechanism cannot do it without the load being taken off.
The load coming off pops the low gear bullets out of engagement and before the load applies to the high gear bullets there is a very very tiny gap in torque transfer.
This gap does not show up on the propshaft trace because of the rotating mass and the damper between the shift mechanism and the sensor position on the propshaft.

#298 24gerrard

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Posted 06 March 2012 - 21:15

Ummm, Gerrard.....no, not talking about take off as it relates to the graph.....the clutch example simply illustrates an easy way to understand the graph's uninterrupted torque flow whilst "slipping" during the Zeroshifts millisecond 1st to 2nd gear change! If it wasn't for the slip and damper I think there would be a spike and then a drop to 2nd gear level torque........depending of course on the software instructions that control the fly by wire clutch etc. and determines the shape of the desired shift trace for that particular situation!

There is no torque flow interruption or gap!

John


Trying to compare using the clutch to drive off from stationary with controlled slip, is like comparing jumping with skiing.
The example you give means nothing.
The torque HAS GOT TO END UP AT THE 2ND GEAR LEVEL, it is how it gets there that is under discusion.
It cannot get there by suddenly dropping as the engine rpm and inputshaft rpm part company UNLESS THE TORQUE IS REDUCED.
You cannot keep a steady rpm at the engine and state it is a POWER ON SHIFT when the torque is going almost strait down as the roadspeed remains constant.
THIS IS A DISENGAGEMENT.
The vehicle only returns to acceleration after the shift completes.

#299 NTSOS

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Posted 06 March 2012 - 21:39

Trying to compare using the clutch to drive off from stationary with controlled slip, is like comparing jumping with skiing.
The example you give means nothing.
The torque HAS GOT TO END UP AT THE 2ND GEAR LEVEL, it is how it gets there that is under discusion.
It cannot get there by suddenly dropping as the engine rpm and inputshaft rpm part company UNLESS THE TORQUE IS REDUCED.
You cannot keep a steady rpm at the engine and state it is a POWER ON SHIFT when the torque is going almost strait down as the roadspeed remains constant.
THIS IS A DISENGAGEMENT.
The vehicle only returns to acceleration after the shift completes.


Sorry to disagree with you but your paragraph means nothing as it relates to reality.......THERE IS NO DISENGAGEMENT!

Bulletin.....Bulletin.....the 2012 Honda MotoGP RC213V race bike's mystery transmission contains Zeroshift technology!

John

Edited by NTSOS, 06 March 2012 - 22:16.


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#300 Fondles

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Posted 06 March 2012 - 21:49

SO IT IS NOT A POWER ON SHIFT THEN IS IT?


Yes it is, as the spark isn't turned off, only retarded.



If it is possible to transfer full torque through the shift components, WHY IS CONTROL NEEDED TO REDUCE ENGINE TORQUE DURING A NON POWER ON SHIFT?


That was for the road car version so as to make the shifts smoother. I am not privy to what the F1 & other racing teams do but I suspect they do not retard the timing and just live with the torque spike as the next higher gear is taken up.
The graph shown above is obviously for a road car and not a racing car, hence the shift at low revs and the smoothness of the torque transfer.