Zeroshift - The Ultimate Transmission??

[camber]

Imagining modifying you normal dog leg manual so you didn't have to use the clutch during shifts! Apparently these guys can do it....

They modify a constant mesh manual (or dog-sequentials i.e F1 & WRC). Then they replace synchro hubs or dog rings with the ZeroShift mechanism then control the clutch and/or throttle.

Just read about this in Racecar Engineering(Pretty credible magazine) and still trying to wrap my head around the fact they can engage two gears at once with out taking your foot off the power and engaging the clutch(in a normal dog leg production manual gearbox).

Zero shift article from Racecar Engineering

[CharlieDigital]

Why not just use CVT? You never have to shift again and, theoretically, you can always keep your engine spinning at the optimum RPM for maximum output.

[mayhem]

VW had clutchless manuals in Beetles back in the 60's...is this significantly different?

[camber]

Why not just use CVT? You never have to shift again and, theoretically, you can always keep your engine spinning at the optimum RPM for maximum output.

Belt CVTs have problems(slipping) with high output engines.

VW had clutchless manuals in Beetles back in the 60's...is this significantly different?

That used a torque converter and not a clutch...

Read the article guys.... This system is passive, doesn't use clutches, planetary gear set to achieve it's results. Your talking foot to the floor no blip in power through the gears and it can be applied to a PREVIOUS manual gearbox!

I did some research and the company is will be able to retrofit T5 and T56 transmissions(think Viper, Corvette) with this technology. It knocked a full second off a TVR Cerbera 0-100 mph time!!!

[Nismo]

Why not just use CVT? You never have to shift again and, theoretically, you can always keep your engine spinning at the optimum RPM for maximum output.

I think they are banned by the rules; otherwise, we would already see performance-oriented CVTs being used in Formula 1.

[Irie_eyes]

camber, do you know how it works or any ideas?
A while back, there was this device that attaches to a manual transmission and allowed for gearing that was in-between gears, so essentially a 5-speed was 10-speeds.
I can't find the magazine that had the car with it. It was a BMW.

[camber]

I think they are banned by the rules; otherwise, we would already see performance-oriented CVTs being used in Formula 1.

Williams was testing a CVT transmission in 1993 but F1 rule makers didn't like it and carefully reworded the technicaly regs effectively banning it(Also, making it very hard to implement a double clutch system). It was said to knock a 1.5s in the 0-100-0 mph time. Pretty impressive especially if your thinking lap about lap times. Another reason why FIA might have not liked CVTs is because it makes cars sound they crap

I have a feeling that Mclaren is going to be using this zero shift mechanism. They are rumoured to have a "double clutch transimision" that has circumvented the rules. However, after reading this I really think they are using this Zeroshift mechnasism because I don't think a straight double clutch transmission in F1 would be legal.

camber, do you know how it works or any ideas?
A while back, there was this device that attaches to a manual transmission and allowed for gearing that was in-between gears, so essentially a 5-speed was 10-speeds.
I can't find the magazine that had the car with it. It was a BMW.

I vaguely remember that transmission, I wonder whatever happened to it....

My first guess is that they replaced the syncromesh with some sort of EMF type mechanism..... but then again it supposed to be a completely mechanical system... Could be something as simple as a spring mechanism though that replaces the syncromesh. That would be my guess. I really posted this up to get some input from you guys though and see if someone in FreshAlloy would take a stab at explaining it. This doesn't seem to be some fradulent or infomercial device because Racecar Engineering wouldn't be talking about in such high regards.

[CharlieDigital]

camber, do you know how it works or any ideas?
A while back, there was this device that attaches to a manual transmission and allowed for gearing that was in-between gears, so essentially a 5-speed was 10-speeds.
I can't find the magazine that had the car with it. It was a BMW.

If it was only sitting in between the gears of a 5 speed, wouldn't it be a 9 speed?

Anyways, if you pick up this month's Car and Driver, there's a short bit on the next Audi TT which will be using a system that is similar. I still think that CVT's are the future tho.

[camber]

camber, do you know how it works or any ideas?

Well benn checking into the site every few months and now it looks like they have a flash animation.

Take a look at is here.

Zeroshift System Animation

It shows a shift sequence from neutral to 1st then 2nd. The system uses these "bullets" that pretension the next gears for no lift shifing. I wonder how this stack up to Audi/VW/Porsche...

Seems like a simple enough mechanical system.

[stealthx32]

I have a feeling that Mclaren is going to be using this zero shift mechanism. They are rumoured to have a "double clutch transimision" that has circumvented the rules. However, after reading this I really think they are using this Zeroshift mechnasism because I don't think a straight double clutch transmission in F1 would be legal.

Do the benefits outweigh doubling the rotating mass? I doubt shortening shifts helps that much.

[Irie_eyes]

I see what "catches" and what doesn't but I don't get it (yet).

[camber]

Do the benefits outweigh doubling the rotating mass? I doubt shortening shifts helps that much.

Thing is there is no shift time and apparently the system can be lighter and more compact the a traditional H pattern syncored gearbox.

[camber]

I see what "catches" and what doesn't but I don't get it (yet).

Please check out this Racecar Engineering Article from June 2005. To be honest I don't have the greatest grasp on the concept yet and I haven't read the below article to give a brief synopsis of the mechanism(I'm at work ). I'm just happy more info is out on this system since there seems to be alot of OEM interest....

Changing Strategies

ZeroShift is based on a racing-style dog box and could share much of its internals with a typical racing transmission. However, that is not to say it is necessarily crude or difficult to drive in normal traffic. The secret to its operation lies in the ZeroShift hubs that take the place of the dog rings. On a normal dog engagement gearbox, the dog rings typically sit between two gear pairs and slide on the shaft allowing the dogs to engage drive through one gear pair or the other. Obviously, as the ring is pulled out of engagement with one set of dogs, there is a break in the transmission of power before it engages with the other set. If it didn’t, then two ratios would be selected at once with explosive results.

In contrast, the ZeroShift hub, instead of having the dogs machined into its faces on either side, has six sliding dogs that the company has christened bullets located in slides around the periphery of the hub (see below). These can be slid from side to side, engaging with either gear pair. This is still very little different to a conventional dog ring. However, where the ZeroShift box differs is in the shape of the bullet ends and the selector mechanism that slides them across. Each bullet has a normal dog profile on one face and a ramp on the other and the same faces are used the other way round on the other end of the
bullet. Also all the bullets are connected to the selector fork via springs.

From neutral (figure 1), the selector fork drags the bullets across to engage with the dogs on the first gear pair (figure 2).

Under acceleration, the three dogs on the gear pair will engage with three of the bullets but not with the other three because their faces are ramped and with be thrown out of engagement if they meet. However, on overrun, these three dogs take the drive on their opposite faces.

In an upward change under power, the selector fork will attempt to drag the bullets across to engage with the dogs on the other gear pair (figure 3). But because they are connected to the fork by springs, only the unloaded bullets will move, while the loaded ones will remain engaged with the previous gear pair because the force exerted by the spring is not enough to overcome the clamping force applied to the dogs by the torque of the engine. However, the bullets that were free to move (figure 4) will engage with
the dogs on the second gear pair that are turning faster (figure 5).

This is the point of ZeroShift where the gearbox is effectively in two gears at once and all hell should be breaking loose. But it doesn’t because the second gear pair’s higher ratio overdrives the first, releasing the clamping force between the dog faces of the latter and the bullets (figure 6). With the force of the springs still acting on them, the bullets are free to slide out of engagement and mesh with the dogs on the second gear
pair. Should they be slow in coming out of engagement on the first gear pair, then they will catch up with the face of the next dog(figure 7) but, because the other face of the
bullet is chamfered, rather than engaging, the dog will hit the ramp and fire the bullet on its way to engage with the other gears. Once all six bullets are engaged with the new gear then drive under power and in overrun is restored
(figure 8).

Drive is continuous and unbroken and will not only work between adjacent gear pairs, but also across the gate between nonadjacentpairs, too.

[Nismo]

That sounds good for upshifts, if you don't wan't to install a genuine sequential tranny, but what about downshifts and the ability to utilize engine braking? Is this a system mainly geared [no pun intended] towards drag racers?

[camber]

Well technically this system would be superior to sequential or semi-auto gear boxes since there are no shift times. I don't see why you would not be able to use this gearbox for downshifts and engine braking.

The gearbox is being targetted towards pretty much every industry that uses gearboxes.

SMG Gearbox - BMW M3


DSG Gearbox (Auto-Mode) - Audi A3 2.0 TDi


GR801 8 speed box - Scania 94D-220


Manual Tremec T5 - TVR Cerbera 4.2


Zeroshift equiped Tremec T5 - TVR Cerbera 4.2

[Nismo]

I see how the downshifts would work; a few degrees of play when you take your foot of the gas, but probably not that big of a deal, at least from the driver's perspective. Some of the graphs look a little enhanced, though. For example, why does the same car with the same gearing accelerate so much quicker in 1st gear--never mind the shifts--with their transmission than with the stock transmission? Still a neat idea; do they say whether we'll see this on a real race car anytime soon?

[Irie_eyes]

I catch on now but I have a crappy way of explaining it in my terms.
That pdf helped. Look at the flat side of those bullets going in one direction, that is where the load is being applied. Once the next gear overdrives the first set can't put a load on the first gear and disengages. At one point both gears are engaged but it naturally disengages.
It's like passing on a baton to a faster runner in a relay race. Once it's in their hand let go.
Pretty ingenious. Actually bad a$$.
Looks like might be a trade-off between the number of bullets vs the size vs the material it's made of.

[Nismo]

It's like passing on a baton to a faster runner in a relay race.

That's a good way to explain it.

[G35RIDER]

Is this the same type of setup as profesional dragsters? I know the don't have a clutch either.

['97 S14 SE Turbo]

I would hate to have those springs pulling the "bullet" fail... Could be the whole weak link in the system.

[Irie_eyes]

I would hate to have those springs pulling the "bullet" fail... Could be the whole weak link in the system.

I'm not sure it's possible.
The spring force is from the selector fork from what I've re-read.
It's impossible for both gears to be engaged at the same time to cause damage. Once the second gear is engaged with the red bullet the first one load is taken off and then allowed to slide over to the second gear.
In fact that ramped area on the blue bullet ensures that the overdriven gear itself will disengage the bullet and slide it over to neutral/second.
After re-reading the pdf notice how upon acceleration the left side of the bullet "dog faces" engage with the gear and has the load. On deacceleration the opposite happens and the right side now has the load and allows for engine braking and just as easy downshifts as upshifts.
It's like a gear tooth split in two and each side allowed to move independently of each other.

['97 S14 SE Turbo]

I'm clear on how the cam aspect of is is suppose to work, but I'm more concerned about the springs used to drive the bullets. This spring pressure gives it the delay it needs so that it can disengage later when overdrives occur. It's a combination of both the cam effect and the springs to move the bullets.

From what Camber posted:

Also all the bullets are connected to the selector fork via springs.

My understand of this system, is this: there's no "hard" linkage between the gear selector and the "dogs". You can jam it into 2nd gear while still in first, and not have the dogs go into 2nd gear until the speed is fast enough. Then once is fast enough, it will engage, and when it finally overdrives the 1st gear, the bullets will disengage from 1st gear.

I'm just fearful of a potential weaklink in the whole system that can render it all useless.

If it's not a weaklink, then the system is beautiful. Surprise it took this long for something like this to appear.

[Irie_eyes]

My understand of this system, is this: there's no "hard" linkage between the gear selector and the "dogs". You can jam it into 2nd gear while still in first, and not have the dogs go into 2nd gear until the speed is fast enough. Then once is fast enough, it will engage, and when it finally overdrives the 1st gear, the bullets will disengage from 1st gear.

I came to that same conclusion when looking at the deacceleration.
IMHO I didn't think you really need a strong spring to move the bullets since it's only the retention angle on the bullets keeping it connected to the gear until the gear is overdriven so I didn't think reliability was a major issue.
What I'm wondering what the thing holding the dogs looks like/made of (and the linkage system).

['97 S14 SE Turbo]

I'm picturing string puppets...

[wperdigon]

this is very interesting find - I wouldn't like to see the video on the site, but it's not posted yet