Seamless Shift

[autogyro]

Gatlin guns do not have useable inertia in the barrels, they are gear driven using a hand crank/ratchet. Let go and the barrels instantly stop. A gatlin gun is not a blow back breech system, the gas flow is irelevent.
The analogy is in the loaded breeches of the barrels.
These can all be loaded just like the gears in the DCGB or the Zero shift system.
Unfortunately the torque can only go through one at a time, you can only fire one round at a time.
Therefore there has to be a time delay between torque going through one gear/firing one barrel and torque going through the other gear/firing the next barrel.
Of course the torque going through one can be reducing as the torque going through the other is increasing but this can only be achieved using clutch slip or some form of preloading and release. This cannot be seamless.
No matter what system you use in a layshaft gearbox of any type, you still have to have a way to increase and decrease the engine rpm at the time of the gear shift. A violent dog clutch change gets close to a very rapid shift, the methods described here simply smooth this out at the expense of shift speed and reliability.

To cogs-insulting me simply shows how much you are grasping at straws.

[Cogs]

Lets start with Zeroshift. A company and technology that was not introduced into this discussion by myself.

ZERO = the time in seconds of the delay between the current gear being loaded and the next gear being loaded......FACT

There is no time between states PLEASE lets stay with this point and and you will have no arguement, in fact if you spent any time looking at the geometry it will become very clear that under a power on upshift scenario it is mechanically impossible for this not to be the case....FACT.

LETS FIRST DEAL WITH THIS ISSUE, AND THIS ISSUE ALONE.

[Cogs]

This has now become a matter of ammusement only.

Time after time you make statements and within few words a contradiction. For example:

Unfortunately the torque can only go through one at a time

Of course the torque going through one can be reducing as the torque going through the other is increasing

ZERO = the time in seconds of the delay between the current gear being loaded and the next gear being loaded......FACT

There is no time between states PLEASE lets stay with this point and and you will have no arguement, in fact if you spent any time looking at the geometry it will become very clear that under a power on upshift scenario it is mechanically impossible for this not to be the case....FACT.

LETS FIRST DEAL WITH THIS ISSUE, AND THIS ISSUE ALONE.

[Cogs]

Forget "neat idea", "transitional friction", "operating temperatue", "proper drivers", "trick methods", "wheelspin", "drivers brains", "ancient technology", "electric vehicles", "marketing gimmicks", "clutching at straws", "dyno rigs", "BorgWarner", "1970", "hybrids", "Gatlin guns" and "blow back breech systems" all of which are your words (autogyro).

AUTOGYRO YOU STATED THE FOLLOWING:

"The 'gap' is a time period where there is little or no torque to be measured at the output shaft. This 'gap' is always present in a stepped gearbox and is the reason why the description 'seamless' is untrue and simply a marketing term."

"So far you have failed to explain the time gap between being engaged in one gear and being engaged in the next gear.
To be seamless, there needs to be no time between the two states."

BOTH THESE STATEMENTS ARE ABSOLUTE RUBBISH.........PROVE ME WRONG!

[Team Bog Trotter]

I guess a Cathrein wheel is more what I am after. If you can imagine the thing keeps on spinning a short time after all the fire works are finished firing and the whole contraption still posseses kinetic energy on the wind-down. But anyway I think the point I am trying to make is that even though the driving force is dormant for a short period during the engine modulation the rotational inertia still contributes to input torque.

[flynfrog]

dont argue with idiots they bring you down to their level and beat you with experience.

[autogyro]

I will remember that flyn, hardly worth you posting.
I know how the systems work cogs.
One gear has the rpm going through it changed one way as the other has the rpm going through it changed the other.
Simple, in theory with full engine torque applied, 'seamless'.

Until you find you have to modify the process to reduce wear and damage to the shift components and reduce the sudden unloading of high torque through the next gear.

Then it is not seamless.

[Cogs]

Simple, in theory with full engine torque applied, 'seamless'.

Thanks autogyro, at least we agree on this atleast.
To be honest this was all I was suggesting.

Reducing wear through modification is the key, if an innovative solution to this is possible through a combination of clutch/engine modulation and torsional damping, and if the transmission engineers at Zeroshift get this consistant and durable then all the best to them.

How likely this is, remains to be seen.


Transmission over........................

[autogyro]

Great Cogs, seems we are after all on the same wavelength.
Enjoyed the banter though, I love a bit of controversy, it livens things up and finds things otherwise unvoiced.
Modern engineers are far to locked in math and seriousness.

At the end of the day, I cannot understand why the whole vehicle industry is still held back with the 'layshaft gearbox'.
All those gears being driven round in a bath of oil wasting torque even though only a small number of them are doing anything in any one gear.
For the 21st century it is very very wasteful.
DCTs have even more losses than conventional layshaft boxes, with either two mainshafts or two layshafts dragging along, instead of one of each.
All going the wrong development direction IMHO and why bother with clutches?
DCTs are not even close to suitable for electric vehicles but then nobody has developed a gearbox to help make EVs more efficient have they, Tesla tried but theirs only lasted 2000 miles so now it doesnt have one and is a waste of space in efficiency terms, already obsolete.
Find me 4 million for Cranfield and I will show you the answer.

[segedunum]

I think xpensive mentioned the word 'discrete' before, and that's exactly what a gearbox with shifting is - a discrete system. The words 'seamless' and 'shift' are logically at odds. No matter how hard you try a discrete system with discrete steps is not seamless because that implies a linear process. A truly linear system would produce no change in engine note whatsoever, and I've never heard any drive system do that. In fact, a linear system will only ever have one gear.

Autogyro is spot on, in his usual inimitable way. When it comes to electric vehicles, or vehicles where the motor is electric at least, we certainly need some serious advances in gearbox technology.

[richard_leeds]

.....

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+1

Never thought I'd see you agreeing with autogyro.

So, how can we all now contribute to a collection for autugyro to go to Cranfield to prove the thing-whose-name-we-shall-not-mention actually works?

[747heavy]

Xtrac shows seamless gearchange alternative to dual clutch transmission

more info here

[autogyro]

It is just another way of smoothing out and speeding up a gear shift between stepped ratios, in a slightly different method to the Zero shift system.
It is still part of a layshaft gearbox, which has all the gears rotating all the time the vehicle is in motion immersed in an oil bath.
The loss of torque from this windage is still enormous.
It remains to be seen if this x-trac system is as smooth and reliable as twin clutch/shaft gearboxes in road cars.
It does have an application if it proves faster with less wear in F1, if it can be proven to be more reliable than current dog clutches. I doubt this, with the unreliability last year from F1 gearboxes that had been speeded up on shifts and lightened in weight to the ultimate level.
Perhaps this is what has motivated the development of this type of spring energy absorber at the end of the shift mechanism, to reduce failures expected in next years units?
The layshaft gearbox remains ancient history IMO.

[Jersey Tom]

The layshaft gearbox remains ancient history IMO.

The wheel is ancient history too (literally) and seems to work just fine.

[autogyro]

The layshaft gearbox remains ancient history IMO.

The wheel is ancient history too (literally) and seems to work just fine.

So how does a wheel actualy do work?