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Quick downshifts


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#1 racersteven

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Posted 12 January 2013 - 19:59

While at the US Grand prix in nov I noticed how quick the Factory Mercedes team were on the downshifts ,they are all bloody fast ,but the Mercedes seemed esp quick going down through the gears . As expected the Hrt and Marussia were slowest . This not something you can tell on tv but you notice at track . Could it be software or gearing ? Also the Red bulls seemed the loudest on their downshift's and sounded different .

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#2 rory57

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Posted 12 January 2013 - 20:50

the downshifts ,they are all bloody fast


Quick is fine, just as long as they are not seamless.

#3 Ross Stonefeld

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Posted 12 January 2013 - 22:39

Double clutch!

#4 gruntguru

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Posted 16 January 2013 - 08:11

I wish we had a transmission expert here.

#5 Tony Matthews

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Posted 16 January 2013 - 08:45

:)

#6 JimboJones

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Posted 03 February 2013 - 12:37

While at the US Grand prix in nov I noticed how quick the Factory Mercedes team were on the downshifts ,they are all bloody fast ,but the Mercedes seemed esp quick going down through the gears . As expected the Hrt and Marussia were slowest . This not something you can tell on tv but you notice at track . Could it be software or gearing ? Also the Red bulls seemed the loudest on their downshift's and sounded different .


It will be down to the software/mechanical design of the gearbox, and also engine response. They are seamless shifting up, but coming down require an engine blip to disengage the previous gear. Once that's done, the dog rings will only be brought together once the ECU knows they won't clash, so there's some incredibly fast thinking going on here. A superior strategy might be able to achieve this earlier. Which brings to the final point, the design of the parts themselves. If the gearbox components are stronger/more reliable, they can take a greater impact loading on a down change, which may support a more aggressive strategy with the software. Just some suggestions...

#7 dav115

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Posted 03 February 2013 - 21:47

I remember reading an article involving (Xtrac?) in Racecar Engineering a few years back saying that one or two teams run clutchless downshifts, so perhaps Merc do that?

#8 JimboJones

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Posted 04 February 2013 - 23:32

I remember reading an article involving (Xtrac?) in Racecar Engineering a few years back saying that one or two teams run clutchless downshifts, so perhaps Merc do that?


All F1 gearboxes do not require the clutch to be disengaged, that's the reason for the blip.

#9 Ross Stonefeld

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Posted 05 February 2013 - 16:55

I don't think the blipping and the clutching are 100% linked.

#10 JimboJones

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Posted 05 February 2013 - 22:05

I don't think the blipping and the clutching are 100% linked.


I don't think you understand gearboxes... why blip the engine if you're going to disengage the clutch?

#11 Tony Matthews

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Posted 05 February 2013 - 22:54

To quote Peter Wright's book 'Formula One Technology' - "While in neutral the drive-by-wire throttle is "blipped" ....to increase the engine speed and to synchronize the gear speeds prior to engagement"

#12 just me again

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Posted 06 February 2013 - 11:56

To quote Peter Wright's book 'Formula One Technology' - "While in neutral the drive-by-wire throttle is "blipped" ....to increase the engine speed and to synchronize the gear speeds prior to engagement"


Yes, but maybe they "blip" the throttle longer and harder, not for the gearbox, but for the velocity of the exhaust fumes.

Bjørn.

#13 Ross Stonefeld

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Posted 06 February 2013 - 12:25

I don't think you understand gearboxes... why blip the engine if you're going to disengage the clutch?


Shape of the gear teeth? No race car I've driven, granted not an exhaustive list, could be adequately downshifted using clutch alone.

#14 Tony Matthews

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Posted 06 February 2013 - 13:04




Yes, but maybe they "blip" the throttle longer and harder, not for the gearbox, but for the velocity of the exhaust fumes.

Bjørn.

To quote Peter Wright's book 'Formula One Technology' -.... to synchronize the gear speeds prior to engagement"

#15 rachael

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Posted 06 February 2013 - 20:54

To quote Peter Wright's book 'Formula One Technology' -.... to synchronize the gear speeds prior to engagement"


To be fair Peter's book was written before quickshift gearboxes were commonplace and all the exhaust blowing lark to increase downforce.

#16 Ross Stonefeld

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Posted 06 February 2013 - 21:07

I think the exhaust maps are different from blipping, they seem to engage regardless of downshift.

Edited by Ross Stonefeld, 06 February 2013 - 21:08.


#17 Tony Matthews

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Posted 06 February 2013 - 22:23

To be fair Peter's book was written before quickshift gearboxes were commonplace and all the exhaust blowing lark to increase downforce.

I realise that, but I couldn't be bothered to write more - a sudden onset of lethargy, probably too warm after getting too cold! However, surely a 'blip' to synchronise gear speeds is so short as to have very little effect on downforce, which is why the blown diffuser was developed. Struggles to reach book. A 2000 RPM increase in engine speed (according to PW) takes about .04 sec - how much extra downforce would that provide? I await your reply, rachael, and if I'm wrong, I'm wrong, I just want to know the answer...

#18 rachael

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Posted 07 February 2013 - 08:06

I realise that, but I couldn't be bothered to write more - a sudden onset of lethargy, probably too warm after getting too cold! However, surely a 'blip' to synchronise gear speeds is so short as to have very little effect on downforce, which is why the blown diffuser was developed. Struggles to reach book. A 2000 RPM increase in engine speed (according to PW) takes about .04 sec - how much extra downforce would that provide? I await your reply, rachael, and if I'm wrong, I'm wrong, I just want to know the answer...


Obviously a .04 second blip isn't going to provide much in the way of downforce. I do know a 'blip' is not necessary for gear synchronisation and is used instead to avoid overloading the rear tyres.

#19 Tony Matthews

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Posted 07 February 2013 - 08:45

Thanks. PW's next sentence is "The last thing the driver wants while braking hard is for the rear wheels to momentarily lock due to a miss-synchronized downshift." As you say, the book is relatively old now - a great shame that the proposed up-date came to nothing. Still a trickle of sales though...

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#20 murpia

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Posted 07 February 2013 - 13:05

Obviously a .04 second blip isn't going to provide much in the way of downforce. I do know a 'blip' is not necessary for gear synchronisation and is used instead to avoid overloading the rear tyres.

The blip is not necessary for synchronisation, but is needed for extraction. I.e. it gets the gearbox out of the current gear, but is not needed to engage the new one.

Regards, Ian

#21 JimboJones

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Posted 08 February 2013 - 00:00

The blip is not necessary for synchronisation, but is needed for extraction. I.e. it gets the gearbox out of the current gear, but is not needed to engage the new one.

Regards, Ian


Thank you murpia! Pretty sure the OP was about F1 downshifts... all F1 cars have seamless gearboxes which do not need to 'syncronise gear speeds'.
Quoting from a 10yr old book is kind of irrelevant, I would recommend searching how seamless boxes work first. As I mentioned in original post, the blip is required to disengage the current gear only, all of which is done with the clutch engaged. Any clutch control is only used to damp the up/downshift, and not required to actually change gear.

#22 Tony Matthews

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Posted 08 February 2013 - 00:27



Thank you murpia! Pretty sure the OP was about F1 downshifts... all F1 cars have seamless gearboxes which do not need to 'syncronise gear speeds'.
Quoting from a 10yr old book is kind of irrelevant, I would recommend searching how seamless boxes work first. As I mentioned in original post, the blip is required to disengage the current gear only, all of which is done with the clutch engaged. Any clutch control is only used to damp the up/downshift, and not required to actually change gear.


The only reason I quoted from "a 10yr old book" was to counter the suggesation made in this post...

Yes, but maybe they "blip" the throttle longer and harder, not for the gearbox, but for the velocity of the exhaust fumes.
Bjørn.



#23 terrywrist

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Posted 08 February 2013 - 03:34

Driving without clutch and with clutch

Edited by terrywrist, 08 February 2013 - 03:37.


#24 Ross Stonefeld

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Posted 08 February 2013 - 13:16

?

#25 rotodyne

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Posted 11 February 2013 - 10:57

For any 'blip' to take place, the geartrain has got to be disengaged.
If it is not disengaged at the primary clutch then it will be disengaged at the gearchange mechanism.
In other words it is not a seamless shift.
During any gear change with a mechanical stepped geartrain the purpose of the gear change is to accelerate or decelerate the engine.
The 'blip' on downshifts is to increase engine rpm to match the lower gear ratio when it is finaly engaged.
This can be achieved with electronic control.
It used to be a double declutch activated manualy.
On upshifts it is only necessary to decrease rpm, which is the constant demand of the rotating engine components anyway.
Simply forcing the gearshift components connected to the input train from being engaged to a low (higher reving gear) in the output train and forcing them to engage with a high (low reving gear) in the output train is sufficient.
It is much easier to decelerate an F1 engine by some 500 rpm than any other IC engine because of the very low rotational inertia.
Peter Wright quotes 0.04 seconds and today this will be less.
Slowing an F1 engine by 0.04 seconds by some 500 rpm can be achieved simply by turning off the ignition or fuel, it is not rocket science or magic shift.

In both up and down gearchanges the geartrain has got to be disengaged from the engine.
During up shifts for less than 0.04 seconds, during downshifts for at least the time taken for the 'blip'.
All the fancy shift mechanisms do is reduce the wear and potential damage to the gearshift components.
By doing so they do allow faster more reliable shifting, however they are NOT seamless.

#26 Kelpiecross

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Posted 11 February 2013 - 12:24

For any 'blip' to take place, the geartrain has got to be disengaged.
If it is not disengaged at the primary clutch then it will be disengaged at the gearchange mechanism.
In other words it is not a seamless shift.
During any gear change with a mechanical stepped geartrain the purpose of the gear change is to accelerate or decelerate the engine.
The 'blip' on downshifts is to increase engine rpm to match the lower gear ratio when it is finaly engaged.
This can be achieved with electronic control.
It used to be a double declutch activated manualy.
On upshifts it is only necessary to decrease rpm, which is the constant demand of the rotating engine components anyway.
Simply forcing the gearshift components connected to the input train from being engaged to a low (higher reving gear) in the output train and forcing them to engage with a high (low reving gear) in the output train is sufficient.
It is much easier to decelerate an F1 engine by some 500 rpm than any other IC engine because of the very low rotational inertia.
Peter Wright quotes 0.04 seconds and today this will be less.
Slowing an F1 engine by 0.04 seconds by some 500 rpm can be achieved simply by turning off the ignition or fuel, it is not rocket science or magic shift.

In both up and down gearchanges the geartrain has got to be disengaged from the engine.
During up shifts for less than 0.04 seconds, during downshifts for at least the time taken for the 'blip'.
All the fancy shift mechanisms do is reduce the wear and potential damage to the gearshift components.
By doing so they do allow faster more reliable shifting, however they are NOT seamless.



"Rotodyne" - sounds familiar - now all we need is Cheapy and that other bloke with the 7 litre Jag.

#27 Tony Matthews

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Posted 11 February 2013 - 12:29

Yes, unfortunately it is he, with the never-ending bollocks. For his information, the quotes about 'blipping' were from an age before seamless gearboxes... Now for the ignore feature.

#28 Kelpiecross

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Posted 11 February 2013 - 12:37

Yes, unfortunately it is he, with the never-ending bollocks. For his information, the quotes about 'blipping' were from an age before seamless gearboxes... Now for the ignore feature.


I think it is actually a good thing to get some "unconventional" viewpoints on different matters - even if they can be slightly ridiculous. This forum has been a little PC and conventional recently.

How did he get a "join date" of the 13th. - time machine?

#29 Tony Matthews

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Posted 11 February 2013 - 14:46

2013, and I'm not asking anyone else to ignore him!

#30 rotodyne

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Posted 11 February 2013 - 16:54



Here we see Ross Brawn stateing that the gearshift does not have to be disengaged and is seamless, then he goes on to state that just before the next gear engages the engaged gear disengages.

In the video 38 to 50

Cant have it both ways Ross.

Edited by rotodyne, 11 February 2013 - 16:56.


#31 rory57

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Posted 11 February 2013 - 19:00

Nice to have our autogyroscopic mate back.

Isn't the point simply that where there is a step change, there is a seam. (whether or not there is a moment of no drive)

#32 rachael

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Posted 11 February 2013 - 20:02

Yes, unfortunately it is he, with the never-ending bollocks.


You mean this bloke?

#33 Tony Matthews

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Posted 11 February 2013 - 21:27

You mean this bloke?

rachael, you surprise me - in the nicest possible way!

Look, this is what is going to happen. One person is going to deny the possibility of seamless gearchanges, either because he has very little imagination, or because he is a troll, laughing his sandels off, deep in the Norfolk (UK) fens. A smattering of people will half-support him because they are not sure about seamless gearchanges. The majority, including some clever engineers with first hand knowledge of state-of-the-art F1 gearboxes will attempt to explain - attempt, not because of the insurmountable problem of explaining it, but the innability of some to comprehend - how a gearbox can operate seamlessly. Result? The same old same old. Nothing new will come from the naysayers, and no amount of technical explanation will be accepted/understood. For that reason, I'm out.

That last expression has cultural significance to those who occasionally watch UK TV.

Sandels may be sandles. May be...

Edited by Tony Matthews, 11 February 2013 - 21:27.


#34 rachael

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Posted 11 February 2013 - 21:39

rachael, you surprise me - in the nicest possible way!


Just seemed totally purile and predictable to me but Viz was big with my friends at uni. For some reason when I read your phrase Buster was the first thing I thought of!




#35 JimboJones

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Posted 11 February 2013 - 21:58

rachael, you surprise me - in the nicest possible way!

Look, this is what is going to happen. One person is going to deny the possibility of seamless gearchanges, either because he has very little imagination, or because he is a troll, laughing his sandels off, deep in the Norfolk (UK) fens. A smattering of people will half-support him because they are not sure about seamless gearchanges. The majority, including some clever engineers with first hand knowledge of state-of-the-art F1 gearboxes will attempt to explain - attempt, not because of the insurmountable problem of explaining it, but the innability of some to comprehend - how a gearbox can operate seamlessly. Result? The same old same old. Nothing new will come from the naysayers, and no amount of technical explanation will be accepted/understood. For that reason, I'm out.

That last expression has cultural significance to those who occasionally watch UK TV.

Sandels may be sandles. May be...


brilliant...

For any 'blip' to take place, the geartrain has got to be disengaged.
If it is not disengaged at the primary clutch then it will be disengaged at the gearchange mechanism.
In other words it is not a seamless shift.
During any gear change with a mechanical stepped geartrain the purpose of the gear change is to accelerate or decelerate the engine.
The 'blip' on downshifts is to increase engine rpm to match the lower gear ratio when it is finaly engaged.
This can be achieved with electronic control.
It used to be a double declutch activated manualy.
On upshifts it is only necessary to decrease rpm, which is the constant demand of the rotating engine components anyway.
Simply forcing the gearshift components connected to the input train from being engaged to a low (higher reving gear) in the output train and forcing them to engage with a high (low reving gear) in the output train is sufficient.
It is much easier to decelerate an F1 engine by some 500 rpm than any other IC engine because of the very low rotational inertia.
Peter Wright quotes 0.04 seconds and today this will be less.
Slowing an F1 engine by 0.04 seconds by some 500 rpm can be achieved simply by turning off the ignition or fuel, it is not rocket science or magic shift.

In both up and down gearchanges the geartrain has got to be disengaged from the engine.
During up shifts for less than 0.04 seconds, during downshifts for at least the time taken for the 'blip'.
All the fancy shift mechanisms do is reduce the wear and potential damage to the gearshift components.
By doing so they do allow faster more reliable shifting, however they are NOT seamless.


douchebag...

Edited by JimboJones, 11 February 2013 - 22:04.


#36 rotodyne

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Posted 11 February 2013 - 22:45

Of course there is always the possibility that I am correct.
Nobody has proven me wrong so far.

#37 Tony Matthews

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Posted 11 February 2013 - 23:08

Just seemed totally purile and predictable to me but Viz was big with my friends at uni. For some reason when I read your phrase Buster was the first thing I thought of!

Your second sentence should have made me feel hip, with it, cutting (old style) edge. Unfortunately, your first sentence rather puts the knockers on it, so to speak. However, in my defence, Viz somehow passed me by.

#38 Kelpiecross

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Posted 12 February 2013 - 02:21

On the subject of seamless gearboxes - I accept (more or less) that the change is uninterrupted/seamless - but I have to admit that I am buggered if I can actually picture just how this mechanism actually works - despite a lot of study of the various explanatory diagrams etc. I suspect there are quite a few people in the same position as I am.

#39 MatsNorway

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Posted 12 February 2013 - 19:04

On the subject of seamless gearboxes - I accept (more or less) that the change is uninterrupted/seamless - but I have to admit that I am buggered if I can actually picture just how this mechanism actually works - despite a lot of study of the various explanatory diagrams etc. I suspect there are quite a few people in the same position as I am.

oh yes. i would like a good animation of it. up and down the gears.

Edited by MatsNorway, 12 February 2013 - 19:04.