Seamless Shift

[autogyro]

Yep absolutely correct.
One ramps down, the other ramps up, brilliant you understand how it works.
Now tell me how long it takes to ramp up one ring and ramp down the other.
Ipso facto a time gap. Not seamless.

[autogyro]

You can of course transmit torque during the 'time' the bullets are ramping up and down.

However if you transmit high figures of torque without control over clutch slip or engine torque output you will either slip the contact points of the bullets, jam the system or achieve excess wear on the bullets which will prevent the system from meeting reliability demands.

I had the only dyno rig capable of testing such shift systems in North London in the early 1970s,I also did consultancy work for both Borg Warners Letchworth and British Leyland (mostly competition gearboxes for John Davenport) so as I said no modern methods.
Almost all motor manufacturing companies do not fully bench test layshaft gearboxes in detail today, because the technology is so ancient, practicaly everything possible has been done and done to death.

[Cogs]

One ramps down, the other ramps up, brilliant you understand how it works.

No it does not, you do not understand the system.

Now tell me how long it takes to ramp up one ring and ramp down the other.

It does not take any time because there is no ramping.

You can of course transmit torque during the 'time' the bullets are ramping up and down.

There is no ramping up and down.

you will either slip the contact points of the bullets, jam the system

Wrong. You do not understand the system.

I also did consultancy work for both Borg Warners

Fantastic coincidence, I was a senior engineer for BorgWarner for 10 years.

I suggest you go back through this thread and read through all of my posts, there is absolute continuity in my claims. When you understand the system (which you blatently do not at this point) feel free to ask any more questions for which I have the answers. What I'm not going to do is repeatedly explain basic facts that you cannot seem to grasp at this point.

Thanks for the banter though it has been entertaining.

[xpensive]

Xcuse me Gentlemen,
Please correct where I go wrong, but the way I undrestand the need and use of a gearbox, or transmission of any kind, is to xchange rpm for torque and vice versa within the power transmitted. How this could possibly be arranged "seamlessly" within machanically discreet steps, is simply beyond my humble engineerish comprehension?

Somwhere, however short in time, there must be a point of no transmission?

[autogyro]

Now I understand your problem and why you are so pro zero shift.

It does not matter if the mechanism you are thinking of ramps up and down or engages directly with dog engagement (plus any engagement shock mechanism), the engine still has to change rpm over a time period as the gear ratio is changed.

Not seamless.

So you worked under Derick Gardener did you?

If you did you must realise that Derick looked at these systems in detail back in the 1970s.

Perhaps they have raised their head again?
It is simply because of the low inertia in current F1 engines and tiny low diameter multi plate clutches (which can only be controlled by breaking the regulations), not a powertrain idea practical for general use.
In any powertrain with higher engine/flywheel clutch inertia, using such engagement systems will be much slower shifting and very low on reliability.
This is why the layshaft development direction in the market, is in dual clutches/shaft systems, to speed the shift 'and' maintain reliability but accepting a higher torque loss as the trade off.

[Cogs]

Look, the single reason I got further involved in this discussion was because autogyro made the following statement.

"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."

This is completely UNTRUE and any telemetry from a DCT or modern evolution of dog box will show this.....FACT

With regard to Zero Shift, I have looked at the geometry and what I have said is true.

Again, as I mentioned before the discussion about seamlessness is completely open and dependant on each definition. I was responding to the definition proposed by autogyro.

[autogyro]

NO.
DCT gearboxes will always loose at least part of the available torque in clutch slip.
Dog boxes, will either do the same, disengage completely or back the ignition and or fuel supply. Unless of course they are full race dog boxes, where they will be fast volent, high on wear and there STILL will be a gap in output torque.

Zero shift simply smooths out a dog engagement at the expense of reliability.

[Cogs]

NO.
DCT gearboxes will always loose at least part of the available torque in clutch slip.

AAAAaaaaaargh!!!!
I know this, this was never part of the discussion, of coarse DCTs loose part of the available torque in clutch slip, this is during a period where output torque is changing though so the reultant loss is not significant when measured at the output. By the way my involvement with BW was not in the 70s but during the development of DQ250 so don't preach about what you think is measurable at the output shaft of a DCT.

Zeroshift is an evolution of a dogbox the reduction of fuelling or ignition does not need to occur until post shift event, at which point clutch modulation can substitute the lost torque to the input shaft.

[autogyro]

Hahaha
All this just to prove that Zero Shift and Seamless are just marketing terms.

[autogyro]

NO.
DCT gearboxes will always loose at least part of the available torque in clutch slip.

AAAAaaaaaargh!!!!
I know this, this was never part of the discussion, of coarse DCTs loose part of the available torque in clutch slip, this is during a period where output torque is changing though so the reultant loss is not significant when measured at the output. By the way my involvement with BW was not in the 70s but during the development of DQ250 so don't preach about what you think is measurable at the output shaft of a DCT.

Zeroshift is an evolution of a dogbox the reduction of fuelling or ignition does not need to occur until post shift event, at which point clutch modulation can substitute the lost torque to the input shaft.

Everyone is using DCTs, even in hybrids, cant understand why they need to use any form of clutch at all but there you go.

[Cogs]

Here we go again..................

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

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.

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.

[autogyro]

Gatlin gun, a rotating multi barrel gun, where multiple barrels are 'loaded',
Unfortunately there is a time 'gap' between the bangs.
Hahaha

[Cogs]

Dementia: a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging. It may be static, the result of a unique global brain injury, or progressive, resulting in long-term decline due to damage or disease in the body.

STAY ON TOPIC.......PROVE ME WRONG

[Team Bog Trotter]

Hi Cogs and Autogyro. I have been reading your strings and would like to input my thoughts. The machine gun analagy is very applicable as it describes the engine torque as pulses (Inertial+Gas+Imbalance). As far as a break in torque this does not happen as the gun barrel remains spinning (just like the movies). While there is inertia there will always be torque to the input shaft. The magnititude of which can be managed through the clutch and will always be positive while the engine is spinning in the same direction. I know this from dealings with my tractor on a daily basis. I have looked on the zero shif website and it appears those bullet ring tings are not independently spung so the ramping described in previous strings does not happen. The analygy i would descripe is like throwing a brush handle into the wheels of a moving bicycle its instantaneous and it means business....there is no break in torque.

[Cogs]