Do modern seamless F1 transmission still give a violent push upon gear engagement?

[NL_Fer]

Trick of a seamless transmission is, that the higher gear is engaged and this increases the outputshaft speed and reduces the input shaft speed. This way the dogtheeth of the lower gear are turned away from eachother. The shift is seamless.

[saviour stivala]

I don’t think that any of the present 6 seamless gearboxes on the grid today have been so lacking behind in development that they still use dog-rings between gears being pushed by shift forks operated by a shift barrel.
Seamless or not, as long as there is a gear-change there is a clear shift between gears, and as long as there is a shift between gears there is a break in power. The modern seamless just reduces that break-time to a bare minimum.
If there is no shift/gear-change/break in power the gearbox would be regarded as a CVT which are not permitted.

[Tommy Cookers]

.... The shift is seamless.

please feel free to define what is meant by seamless
(is this only the 'uninterrupted' that Honda highlights ?)

if not ....
the PU is doing 12000 rpm
then quasi-instantly doing 10500 rpm
but there's nothing apparent or measurable ?
(no spike or surge in energy transfer rate due to quasi-instant change in PU rpm and KE ?)

[gruntguru]

‘There will be some jolt’. Yes. There will always be as long as a gear ration change takes place. No matter how near to zero jolt development progress will get the jolt. Zero jolt in gear ration change can only be achieved with a CVT gearbox.

Seamless upshift without jolt can also be achieved with a dual clutch transmission. Two ratios are simultaneously engaged and the taller ratio takes responsibility for drive by progressively engaging its clutch while the clutch for the lower ratio is progressively disengaged.

[gold333]

I think in this thread it's important to differentiate between a difference in pulling capacity that is noticeable between shifts (jolt) or kick in the a$$.

And between a simple vibration that is felt when gears are changed (thud).

Maybe there is no jolt but there is a thud in seamless shifting?>

Edit:



It looks like on conventional gearshifting in F1 (pre seamless) the in put shaft torque GOES DOWN by 300Nm for 50ms.
So that feels like a loss of power/DECELERATION/body going forwards for 50ms during a shift.

On a seamless shift the time is difficult to measure because of varying oscillation over a period of 25 ms, but you can say the shift takes around 8-10ms. The interesting thing is that input shaft torque GOES UP by 100nm during the 8ms. SO instead of a deceleration felt between shift it feels like a small ACCELERATION. I don't think you can feel it at 8ms though.

But all in all I am almost 100% you feel a vibration or something. Then again I'm not an engineer. Real engineers feel free to correct me.

[NL_Fer]

.... The shift is seamless.

please feel free to define what is meant by seamless
(is this only the 'uninterrupted' that Honda highlights ?)

if not ....
the PU is doing 12000 rpm
then quasi-instantly doing 10500 rpm
but there's nothing apparent or measurable ?
(no spike or surge in energy transfer rate due to quasi-instant change in PU rpm and KE ?)

I mean uninterrupted power delivery.

A traditional box a few ms of 0 power transfer. A seamless box always has power transfer. But the reduction in speed of the input shaft is converted to a torque spike. The clutch/mgu-k/ignition can soften the spike, but there will always be power delivery to the wheels.

[saviour stivala]

‘Uninterrupted power delivery’. When increasing or decreasing a drive ratio between driver and driven shafts/input and output shafts can only be achieved with a CVT type of gearbox. A CVT type of gearbox was banned by F1A. A twin friction clutch each one on separate input shaft type of seamless shift gearbox was also banned by the FIA, as it was deemed as a type of CVT gearbox. When the first seamless shift was approved by the FIA, some teams were saying that it is also a type of CVT gearbox. But the FIA approved its use as the seamless shift gearbox has a clear shift between gears and so has a break in power, this clear shift between gears/break in power is as a result that it is not possible engage two different ratios gear at the same time. The actually engaged ratio is the one which is transmitting the power from input to output shaft. The so called ‘engaged’ other gear is not and cannot be transmitting power at the same time as the engaged gear, it will be free-wheeling. A free-wheeling gear is technically not engaged.

[NL_Fer]

The technology has never been disclosed by the teams or gearbox makers. So only insiders know, how their system works.

What I understand about the basic principle is: car is accelerating, before the shift, (dog)ring is partly disengaged, but the current gear is still being driven by a ratched or sprag clutch type of connection. So effectively the input shaft can only drive the output, not the other way around, no engine braking.

Now the higher gear is engaged, increasing the output shaft speed. At the exact moment this happens, the previous gear driven with the ratched/sprag clutch is not transmitting power anymore.

[saviour stivala]

The driver changes gears. So there have to be gear changes. A gear change means a change from one gear to another. A gear change means a ‘clear shift’ between gears which also means there is a break in power. No matter how near to ‘ZERO TIME’ the shift/change of gear have been developed into, it is not down to ZERO TIME’. If it was down to ‘ZERO TIME’ there would not be a clear shift between gears/a break in power. And the gearbox could be called a CVT box which is not permitted.
A car is accelerating or decelerating through the gear the driver have selected/changed into. The next gear in sequential order to that selected by the driver, higher if upshifted or lower if down shifted, is not and cannot be engaged at the same time/transmitting power at the same time, no matter the system/technology used. The next engagement will have to be made by the driver.
No team is going to disclose the technology it uses. But the technology used will have to respect the regulations.

[Dr. Acula]

The technology has never been disclosed by the teams or gearbox makers. So only insiders know, how their system works.

What I understand about the basic principle is: car is accelerating, before the shift, (dog)ring is partly disengaged, but the current gear is still being driven by a ratched or sprag clutch type of connection. So effectively the input shaft can only drive the output, not the other way around, no engine braking.

Now the higher gear is engaged, increasing the output shaft speed. At the exact moment this happens, the previous gear driven with the ratched/sprag clutch is not transmitting power anymore.

It's simply a question of the right timing.

[stez90]

As a Toro Rosso engineer explained us in a university lecture, there is non power break during shift. The dogteeth of gears have a small "backlash" from driving to driven direction (when torque is reversed). You can engage the upper gear while the current one is still engaged using this backlash. As soon as the new one start to "drive", the shaft accelerates, so the lower gear dogteeth become "driven". But this is not an instantaneous event, because of the backlash. While the teeth are recovering the backlash, you have a very small window of time where they are unloaded and you can disengage them. Too late and you destroy the whole gearbox. But current controls are fast enough and up to this task.
So all you have is a positive spike in acceleration due to the crankshaft inertia, but no power interruption.

[Dr. Acula]

As a Toro Rosso engineer explained us in a university lecture, there is non power break during shift. The dogteeth of gears have a small "backlash" from driving to driven direction (when torque is reversed). You can engage the upper gear while the current one is still engaged using this backlash. As soon as the new one start to "drive", the shaft accelerates, so the lower gear dogteeth become "driven". But this is not an instantaneous event, because of the backlash. While the teeth are recovering the backlash, you have a very small window of time where they are unloaded and you can disengage them. Too late and you destroy the whole gearbox. But current controls are fast enough and up to this task.
So all you have is a positive spike in acceleration due to the crankshaft inertia, but no power interruption.

Yes, you can see this actually in this video.

It's an older gearbox but what is pretty apparent is that you have nearly a quarter of a revultion "play" until the next set of teeth would engage.

[Jolle]

With these kinds of times, the crank itself already isn’t seamless. With the current V6, there are three gaps of no power per revolution. So, with the right timing you can shift during these gaps. Or, skip one or two “bangs”.

[saviour stivala]

The gearbox in that excellent video is semi-automatic sequential with dog-clutch and fork between gears and not a not a seamless gearbox, let alone a modern one which does not use a dog-clutch and fork between gears and neither a gear selection actuator barrel. The gear change time between the gearbox in that video and that of a seamless gearbox is not comparable.
All of the 6 present day sequential gearboxes on the grid as well as all makes of sequential gearboxes used in motogp, although different makes may differ in their gear selection detail, they all follow the sequential gear selection methods developed by Honda in 2008-9. A design that eliminated the use of dog-clutch and fork between gear as well as the gear selection barrel. The Honda developed gear selection method design pushed the sequential gear change time to new lows apart from the tremendous advantage achieved in size and weight. But apart from their seamless gear change design ultralow time achievements. Honda still had to tame the power spikes between gear changes by electronic control of the engine.

[strad]

Thanks all but back to the original question I can't help but think the OP is talking about feeling you get from changing ratios from say first to second gears.
Sorry if I'm wrong but that's my take away from the original post.
The answer I think with that understanding is that yes you still feel the effects of changed gear from the changed ratio and therefor not truly "seamless" like a CVT would be.
I have never driven with a CVT but that is the number one complaint people have.. the lack of shifting gears sensation.