asking about gearbox

[machin]

Do they take away power (blip the engine)

[sigh] Auto, please TRY not to confuse your terminology... It makes following your posts so tiring...

Blip the Throttle. Meaning: Blipping the throttle is simply applying a short stab of throttle.

Anyway... All you need to do is provide an externally referencable quote from a credible source that backs up your claims and all will be forgiven!

[machin]

Because I'm kind like that... I couldn't just sit there and leave everyone to your conspiracy theories Auto... so here's an example of externally referenced, credible sources, explaining modern gearbox technologies:-

“There are several advantages to the semi-automatic gearbox. First, the driver gets to keep both hands on the wheel, so it’s easier for him to get the maximum from the car – particularly through fast corners, when the steering gets very heavy. Second, you can change gear in 30-50 milliseconds as opposed to 200-250 milliseconds, so it’s significantly faster.

“Some people tell me that F1 would be better if the drivers still used stick shifts, but that’s a bit like saying, “isn’t it a pity we don’t still walk around in clogs!”

Full article: http://www.racecar-engineering.com/tech ... gearboxes/

In a traditional racing ’box, drive is transmitted from the input shaft (direct from the engine) via toothed dog rings that sit between the gear pairs and are moved from one gear to another by the selector fork. Owing to the speed differential, the power has to be interrupted while the dogs disengage from one set of gears and bind with the next. You do that by backing off the throttle (or use electronics cut the ignition briefly). Even so, the torque surge as the engine moves almost instantaneously to a lower part of the rev range puts a strain on the gearbox internals and can actually break driveshafts, especially if the rear wheels are oscillating – such as happens if the driver changes gear on a rumble strip or over bumps. The dynamic torque peaks during a gearchange can be 10 times the static torque; if the timing is out, those forces can chip or strip the teeth of the dog and gear rings. And, as teams seek to shave fractions of a second from the shift time, the risks increase.

Why go to all this trouble to minimize those final few milliseconds in which the car isn’t accelerating at full power? Because it isn’t only not accelerating: during that fraction of a second when power isn’t being sent to the road wheels, the aero drag is so great that the car is actually decelerating. The effect only increases as the speed (and therefore the downforce generated by the wings) rises. It means that during a shift, say, from sixth to seventh the transient deceleration is equivalent to braking hard enough to lock the wheels of a high-end road-going sports car.

So the holy grail of the seamless-shift gearbox is to replace the dog rings with something else – something that selects the next gear before the current one is disengaged. The reason for that vague description of “something else” is because every team running a seamless-shift gearbox has developed its own closely guarded secret technology”

A few years later more details started to emerge:

Rather than one barrel to move the selector forks the seamless gearbox has two, one operating the odd ratios and the other operating the evens. With one gear still engaged the other barrel is rotated to engage the next ratio. As the new gear's dogs meet, they pick up the drive, taking the load off the previous ratio. However, before the unloaded gear's dogs can swing around and engage with their opposite faces, their barrel is rotated to snatch them out of engagement.

But what about the problem of the inevitable torque spike when the inertia of a fast spinning engine is slammed into a set of dogs connected to some sticky racing tyres? Phil Roper, principle engineer, explains that it has not proved to be a problem. The total variation of torque [with the seamless shift technology] is actually smaller and can easily be absorbed by the wind up in the drivetrain. The drivers say it is very smooth and actually unsettles the car less in corners.
Typically seamless shift technology is worth approximately 3 tenths of a second per lap.

The performance advantage was backed up by f1Racing magazine:

“The advantage a seamless-shift gearbox confers is reckoned to be in the order of half a second per lap”

[autogyro]

Do they take away power (blip the engine)

[sigh] Auto, please TRY not to confuse your terminology... It makes following your posts so tiring...

Blip the Throttle. Meaning: Blipping the throttle is simply applying a short stab of throttle.

Anyway... All you need to do is provide an externally referencable quote from a credible source that backs up your claims and all will be forgiven!

I said 'blip the engine'.
I would far rather you worked it out for yourself just as Patrick Head did after I discussed it with him back in the day.

[autogyro]

http://oi32.tinypic.com/sl5ico.jpg

Please feel free to ask Patrick but mention our meeting is still covered under this agreement.

[machin]

I said 'blip the engine'.

Exactly my point; you're mixing your terms: Did you mean to say "blip the throttle' or "cut the ignition"..??!

I would far rather you worked it out for yourself just as Patrick Head did after I discussed it with him back in the day.

What did I say earlier about your Name-dropping BS? We can all play that game... I could post many client confidentiality agreements, what does that prove? Come on man, external links from credible sources to back up your claims... That's all we want.

[NL_Fer]

No they are not. The main difference between a seamless shift and a conventional box, is that the seamless doesn't lockup, when both gears are engaged. A DCT is not seamless, still a gear needs to be disenaged, before a new gear can be engaged.

The key about a seamless shift, it can actually engage a higher gear, while current gear is still engaged. The higher gear will increase the outgoing shafts speed and this action will disengage the lower gear.

The higher gear cannot increase the outgoing shaft speed until the engine rpm is decreased and the lower gear is disengaged.
Until that point in the shift overlap, engine torque cannot be transmitted to increase output speed and create acceleration.
Flywheel (no flywheel) inertia is not sufficient alone to accelerate the car.

Yes a seamless box can. To be more precise, a seamless box has two "dog kinda" rings. One for the engine to drive the outgoing shaft, another for outgoing shaft driving the engine, in overun (off trottle) situations. So in gear they are both engaged, acting like a normal box.

Now to shift, the overun ring is disengaged. Which leaves the other ring driving the outgoing shaft, but if the output shift would increase it's rpm, it cannot take the inout shaft with it. Drive is only possible from engine to wheels in this situation.

So when a higher gear is engaged, the output shaft is increased and the engine reduced. Now there would be no drive anymore from the lower gear.

Only problem could be the shock introduced by the higher gear engaging, but i think it can be dealt with, by a cut ignition for just 1 or more powerstrokes.

[autogyro]

So if you cut the engine what accelerates the output shaft?

[flynfrog]

So if you cut the engine what accelerates the output shaft?

momentum in the rotating assembly

[Seattle]

I hate to start a new thread with my first post so if you don't mind (since this is a gearbox thread), can somebody tell me what "Learn all the gears" means when they tell the driver that before the start?

Edit: Actually I'll specify the question a bit more. After the driver get's that message before the start, what exactly are would they do? Sometimes the engineer might even say something like "learn gears 7 and 8" if I recall.

Also I just wanna say I appreciate what this board does. my background not engineering although it is science so as a fan of F1 I at least have an appreciation for technical aspect of this sport. as for a transmission that can have two gears engaged at the same time (even for a brief time), that is mind boggling to me.

[Pieoter]

This might be able to help

http://zeroshift.com/pdf/RcarN6V15_Zeroshift.pdf

[NL_Fer]

Since we don't exactly know how each teams seamless technology works, this is hard to tell. But we know there is a limited time frame, where the older gear can be disengaged, after the higher gear is engaged. Maybe they need to adjust the moment they need to disengage the older gear.

[autogyro]

So if you cut the engine what accelerates the output shaft?

momentum in the rotating assembly

So they dont need a running engine then just more mass in the engines rotating parts?

[autogyro]

Two gears are NOT delivering torque at the same time, even though companies like zero shift would like you to think so.
In a constant mesh lay shaft gear box, ALL gears are engaged at the same time by virtue of the design.
So the term engaged is misleading.

It is certain components of the shift over lap mechanism that are engaged at the same time during a shift.

Engine torque cannot be delivered to the rear wheels through two gears at once.

The argument here is whether the output accelerates to disengage the lower gears shift mechanism.
Or does the shift mechanism during the cut in engine torque delivery disengage the lower gear and allow the higher gear shift mechanism to reduce engine rpm before complete engagement.

Send your answers on stamped addressed kinetic energy algorithms that need to be chosen for each gear change to stabilize energy harvesting.

[Tommy Cookers]

now energy harvesting is the problem ?

the (crankshaft-referred) inertia of the mgu-k is small relative to the corresponding inertia of the ICE
and the generating load from the mgu-k is electrical and can be managed millisecond-by-millisecond
so the task caused by downshifts is not a big problem (to the management of rear friction brake pressure)

more evidence that these F1 rules didn't grow on a tree - they were designed by people who knew what they were doing technically

yes of course there are other (more elegant but disruptive to F1) ways of integrating multiple energy flow devices
eg as with Toyota's and other hybrids
(yes, 'mixer' transmissions that get continuous rato variability for free - maybe a new idea a century ago)

[machin]

Engine torque cannot be delivered to the rear wheels through two gears at once.

The aim of the seamless shift is to smoothly transfer drive from one ratio to the next, not specifically to drive both gears at the same time... so that positive force is always applied to the drive train so that there is no deceleration (due to aerodynamic drag) between gearshifts.

How is that possible? Actually we all do it everyday in everyday life... Below are a selection of photos I took of me picking up a camera case off the edge of the table:-

Picture 1: The Camera case at rest, sat on the table. Positive upwards force is applied by the table (preventing it falling on the floor).

Picture 2; shows my hand coming in to grab the camera case. This is filmed at 125 frames per second, and you can see that my hand is moving pretty fast (there's a high relatively difference in speed between my hand and the table). The camera case is still supported by the table.

Picture 3: The camera case is now fully in my hand, not supported by the table at all and traveling at the same speed as my hand (otherwise it wouldn't be in my hand).

At no point in those series of 3 photos does the upwards force acting on the camera case decrease (if it did the case would accelerate towards the floor; F=m.A afterall)...

Picture 4: If we use a much faster film speed (1000 frames per second in this case, hence poorer quality), there is a selection of a few frames where the camera case is both supported by the table and my hand; despite the fact that the table is stationary and my hand is moving rapidly.

Obviously in this small time frame where the camera is supported by both the table and my hand the case must accelerate up to the speed of my hand, and since F still = m.A this means there must be a momentary increase in force on the object... But Xtrac already already explained this:

Phil Roper, principle engineer at Xtrac, explains that it has not proved to be a problem. The total variation of torque [with the seamless shift technology] is actually smaller and can easily be absorbed by the wind up in the drivetrain. The drivers say it is very smooth and actually unsettles the car less in corners

.

Although the table in the photos is "at rest" it is still a valid example as the point here is that there is a relative difference in the speeds of the two things which are applying force to the object during the transfer of load. (In fact: both the table and my hand are travelling through space at some huge speed, and neither is "at rest").



So "the trick" is creating the mechanism that does the load transfer from one gear to the next, and not the actual physics behind the smooth transfer, which you can see is not "magical" or "impossible" at all....