Stripped F1 Gearbox

[hardingfv32]

whats the improvement over the old system though?

The whole discussion is a little vague. What is the definition of 'seamless' in this discussion? As far as I am concerned the only 100% torque during shift system would be dual clutch if we are using the standard gear cluster. Everything else would seem to require a major reduction in torque levels for some amount of time. So then the challenge with a single clutch system is too reduce this down time to a minimum.

Brian

[jenkF1]

whats the improvement over the old system though?

The whole discussion is a little vague. What is the definition of 'seamless' in this discussion? As far as I am concerned the only 100% torque during shift system would be dual clutch if we are using the standard gear cluster. Everything else would seem to require a major reduction in torque levels for some amount of time. So then the challenge with a single clutch system is too reduce this down time to a minimum.

Brian

Don't ask me ask Martin Brundle! Remember him nattering on stating that teams have moved to a seamless gearbox system and force india have caught up. So was just wondering what the main difference is with the system used now and say the system the midfield teams were using in say 2006?

To be honest if you told me anyway I wouldnt get it so dont bother. Im trying to get my head round the basics. Also Martin Brundle may have just been being a loon.

I've read the Ferrari F2002 and a pretty trick gearbox, not sure how reliable sources are but at least wiki states about a 'clutchless box'.

[hardingfv32]

Remember him nattering on stating that teams have moved to a seamless gearbox system and force india have caught up. So was just wondering what the main difference is with the system used now and say the system the midfield teams were using in say 2006?

1) We don't know what seamless means, especially if it is true that the teams are not using two clutches at this time.

2) 'Clutchless' does not imply 100% torque during the shift or even 'seamless'. Most racing gearboxes have been 'clutchless' for decades.

Brian

[Pierce89]

Frankly the F1 gearbox shown looks hardly any different from the pre-1908 gearboxes we have in skeleton cases for the vintage cars we sometimes rebuild.
Lighter smaller and faster but thats it.

Is he back?

[Pierce89]

Tum te tum.

If there is a torque spike, then 100 percent torque is NOT being transmitted during the shift.
Would you explain the version of Newtonian Physics you are basing this 'constant' torque transfer gearshift illusion on?
It is not of this world.

come on man. Attitude like this was what caused people to have a problem in the first place.

[Cogs]

Enjoy these discussions but find it annoying when others simply rubbish comments without putting forward a constructive argument. I'll be more than happy to hold my hands up if proven wrong but this is how I see it.

If the regulations state(d) that there was (is) a requirement for a period of time during a gearshift where powered acceleration was (is) prohibited then I guess the aim is to minimise or counteract this removal of engine torque during the shift.

The first advantage of changing the design to have 2 shift barrels is that the removal of engine torque is not required to be able to disengage the current gear. The second is that splitting odd and even gears means that the new gear can be engaged while driving in the current gear.

If we accept that the transmission architecture allows us to remove this neutral state then we can look at the effect of the engagement. Taking an example of shifting from 1st to 2nd and for now assuming that the shift can be powered by the engine through the event.

When driving in 1st the output shaft, all dog rings (which are attached to the output shaft) and first gear are all traveling at the same speed. 2nd gear is rotating faster because of constant mesh. The engagement of 2nd gear "synchronises" 2nd gear to the output shaft. In order to sychronise 2nd gear the engine also has to be synchronised by this contact. This causes an extremely large positive torque as the synchronising engine inertia is dumped onto the input shaft. The result is an acceleration of the vehicle.

If we can get this far it is clear that there is an excess of torque available during such an event. If either the regulations demand or if durability requires there to be a removal of powered acceleration then the timing of this "cut" can still result in the output shaft having a continuous flow of torque as it eventually reduces from 1st gear output torque to 2nd gear output torque. If the engine is "cut" at the instant of engagement and reinstated prior to synchronisation then we have a solution because the torque is being supplied by the synchronising inertia for these few milliseconds.

The definition of "seamless" will always cause an argument. If we assume that the definition is that the output shaft has a continuous flow of torque whether this is being supplied as powered torque or by inertial torque during synchronisation then the transmission discussed meets the criteria.

[Richard]

I read "seamless" to mean a continuous usable torque to the wheels in practical terms. That allows a negligible microsecond interruption that is unnoticed by the driver.

Autogyro is comparing that with shiftless or continuous transmission. The difference between shift and shiftless is that energy is wasted because no matter how much you may not notice the shift, but it does exist and that wastes energy.

You can then go onto the wasted energy of the shafts spinning at all times. If we had 7 shafts for 7 gears the you'd only need to spin 3 at a time (one engaged, plus one up and one down). You'd still have the shift between stepped gears.

So that's why CVT and other shiftless systems are is so tempting, the problem is that they tend to have their own set of problems and energy losses. There's an appealing robustness about geared cogs engaging and transmitting power from tooth to tooth. It would seem that robustness outweighs the elegance of a shiftless system.

[hardingfv32]

Enjoy these discussions but find it annoying when others simply rubbish comments without putting forward a constructive argument. I'll be more than happy to hold my hands up if proven wrong but this is how I see it.

The point of your thesis is still not clear.

Are you saying that the inertia of the car, transmission, engine, etc? are providing torque during the 'cut' process? Will energy be required to reestablish this inertia after the shift?

Are you saying that there is not a total loss of torque during the 'cut' process? Can you assign a ballpark % figure to the torque you think is available during the 'cut' process?

I am not on the same page as you.

Brian

[strad]

The second is that splitting odd and even gears means that the new gear can be engaged while driving in the current gear.

What I said.

[hardingfv32]

The second is that splitting odd and even gears means that the new gear can be engaged while driving in the current gear.

This is not an accurate statement.

Only one gear can be engaged if 'engagement' means no slippage between the input shaft and output shaft of the transmission.

If 'engagement' means interlocking the gear and slider cogs, then a dual clutch system would be required to engage more than one gear.

Brian

[strad]

If 'engagement' means interlocking the gear and slider cogs

Perhaps I'm wrong, but that is what happens..

[Just_a_fan]

The second is that splitting odd and even gears means that the new gear can be engaged while driving in the current gear.

This is not an accurate statement.

Only one gear can be engaged if 'engagement' means no slippage between the input shaft and output shaft of the transmission.

If 'engagement' means interlocking the gear and slider cogs, then a dual clutch system would be required to engage more than one gear.

Brian

c.f. zeroshift. They have two gears momentarily engaged at once and only use one clutch. And there is no slippage between shafts either.

[hardingfv32]

The holy grail of 'seamless' shifting!

Thanks for the input. It is a good day when you learn something.

Brian

[autogyro]

The second is that splitting odd and even gears means that the new gear can be engaged while driving in the current gear.

This is not an accurate statement.

Only one gear can be engaged if 'engagement' means no slippage between the input shaft and output shaft of the transmission.

If 'engagement' means interlocking the gear and slider cogs, then a dual clutch system would be required to engage more than one gear.

Brian

c.f. zeroshift. They have two gears momentarily engaged at once and only use one clutch. And there is no slippage between shafts either.

If you had two gears engaged to input and output at the same time trying to transfer torque, the geartrain would grenade.
I have seen it and done it more than once.
Zeroshift 'speeds up the shift' it does not replace it.

[Caito]

zeroshift has a torque spike if I remember right. Hence, it wouldn't be logical to call it seamless shift.