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GP TECHHONDAS RC212V GEARBOX

MCN

STORYBEN PURVIS PHOTOGRAPHY GOLD & GOOSE AND BEN PURVIS

Seamless-shift gearboxes will appear in roadbikes by 2012 the technology straight off Hondas RC212V MotoGP machine ondas 2011 RC212V MotoGPbike was already looking hard

to beat even before the firstround of the championship,with all fingers pointingtowards the firms mystery

seamless-shift transmission system as thereason for the bikes new-found pace.

While details of Hondas gearbox are still aclosely guarded secret, several experts havesuggested that British gearbox specialistsZeroshift could be behind the technology. Sowe thought wed pay them a visit to see justwhats going on and discovered that, far frombeing a purely race-oriented technology,seamless-shift gearboxes are on the verge ofappearing on production machines.

Although confidentiality agreementsmean Zeroshift wont mention the names ofthe companies its working with, its clearthat Hondas MotoGP transmission, whichis estimated to be worth between 0.3 to0.5 seconds per lap, is either a Zeroshift-designed system or something very similar.More surprising is the fact that, far frombeing a race-only set-up, Zeroshift saysits already working with more than onemajor manufacturer with the intention ofintroducing exactly the same technologyon production bikes.

Zeroshift design engineer Darren Mescallsaid: Were just on the verge. Its takenfive years to develop an operating systemand in the last year weve had at least twocustomers who are willing to go further.Theyre in the late prototype stages, sotheyre testing at present and, certainly b ythe end of the year, we should have a largeannouncement to make to say were goinginto production.

So it appears that seamless-shiftgearboxes will be in showrooms soon, maybe

even as early as next year, but what are they?Whenever you change gear regardless of

how fast you do it and whether or not you usethe clutch youre disengaging one gear andcreating a momentary gap in power deliverybefore the next ratio is engaged.

Basically, for a brief moment, your bikeis free-wheeling. If youre accelerating

that means theres a moment where theacceleration stops, resuming again when thenext gear takes up drive. If youre changingdown it means youre losing the engine-braking effect for a moment. On the road itsrelatively easy to paper over these cracks inpower delivery with a bit of deft clutch andthrottle control, but thats not addressingthe basic problem and on the track thosemoments with no power add up over a lap,resulting in a significant loss in pace.

Seamless-shift transmissions solve theproblem, switching between ratios withoutever cutting drive to the rear wheel.

HOW IT WORKS

There are several firms developing seamless-shift transmissions but Zeroshifts design isprobably the best contender for use in bikesthanks to its ability to replace a conventionaltransmission with minimal changes to the

transmission casing or the gear linkage.Taking just two gears as an example

say first and second both can spinfreely on the output shaft of the gearboxand are permanently meshed with theircounterparts, which are firmly fixed to theinput shaft. On a normal dog gearbox,a dog ring, sliding along a spine on theoutput shaft, sits between the two gears.Slide it one way and lumps on the side of theadjacent gear (called dogs) will engagewith matching notches in the dog ring, so the

dog ring locks the gear to the output shaNow the input and output shafts are bothspinning; youre in first gear.

Slide the dog ring the other way andanother set of dogs engage the second gratio. In between will be a space where tdog ring can spin, engaging neither gearthe neutral position.

Zeroshifts system allows the changeofrom one gear to the next without havinggo through that neutral position.

Between the gears it has two bullet rineach holding three bullets specially shdogs that can engage onto teeth on the sof the gears. To select first gear, one rinmoved until its bullets hook onto the drivteeth on the side of f irst gear. The seconring is then moved the same direction, itbullets filling in the gaps between the teso theres no slack, or backlash, if youcome off the throttle.

The clever bit is that this second set obullets isnt under any load, the ring holthem can be easily slid across towards tsecond gear. Because second will be turfaster than first, the teeth on the side ofthat gear will hook onto the dogs, in turnaccelerating the output shafts speed. Thbullets that were taking the load from firgear will therefore be unloaded and the

holding them will be able to slide acrosstaking up the backlash on second gear.

Dont worry if you dont get it if you nto see how it works there are animationthe Zeroshift website that make it clear aday (www.zeroshift.com).

Mescall said: One of the major benefis that not only is it seamless on an upshfor acceleration, but also during a downswhich is critical for fast cornering or latbraking. You can even change gear mid-corner without upsetting the vehicle.

SEMLE S

ST TR N NS II

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3

1. Darren Mescall operates asmall hand-wound model of the

seemless-shift transmission

2. First gear fully engaged noticethe left dog teeth merging with the

bullet ring

3. Second gear fully engaged notice bullet ring on right

now fully engaged

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WHT RE THE

DVNTGES?

Of course, having the ability to change gearwithout any loss of drive is a serious bonus as shown by Honda in MotoGP. But its byno means the only thing that the Zeroshifttransmission has got going for it.

Another is the systems versatility since itgives manufacturers the option to introduceautomatic gearboxes or semi-autos withminimal expense or complexity.

Mescall said: We have various options,for an automated or manual system. Thats

the beauty of having low actuation forces.A lot of motorcycle riders want to be

able to feel the mechanical connection,to feel the gear changing, and we can stillmaintain that with this system, using justthe power of the riders foot to change gear.

With systems that are automated, youcan take the element of rider error out of

the equation, so you have advantages ofsafety, fuel economy and emissions.

Bill Martin, managing director ofZeroshift, adds: What you get from it is thebenefit of an automatic bike if you want it.You just put it in drive and most peopleprobably would just do that, even if theythink theyd prefer to use the manual mode.You know on cars they often have paddleson the steering wheel to change gear? Mostpeople use those for the first two d ays, thenthey just rely on the fully automatic mode.

The performance is there. The fueleconomy gain is there. Youre always in theright gear if you put it in drive. Its good foremissions and its good for the stability ofthe bike youre not interrupting thetorque so youre less likely to losecontrol during a shift.

You can operate itvia shift by wire,with either noclutch lever

or with a clutch-by-wire system, and thatmeans theres no way of damaging thesystem the software protects it regardlessof what the rider does. Better for the bikeowner, and better for the manufacturerand their warranty.

Martin is keen to point out that, whilethe attention might be on racing and high-performance bikes, even scooters couldbenefit from the system.

The belt CVT system is not efficient,Martin says. Weve heard figures rangingfrom a 20 percent loss to a 35 percent loss.Thats simply not sustainable. Switchingover from CVT to seamless shift meansits basically the same experience for thescooter rider, but with 20 percent moreacceleration and 20 percent less fuel

consumption. And made in big enoughnumbers we may be able to bring theprice down to match the cost of a CVT.

In terms of how much thesystem will cost when added to a bike, as usual the defining

factor will be the level of production.If its an extra, and a niche extra, then

its always going to be more expensive,Martin says. But if thats the only way thebike comes then its going to be the sameprice as the bike used to be.

Scooters may be something thatthe future holds for Zeroshift, but if aproduction machine appears in the nearfuture its likely to be something moreexpensive probably a superbike ora tourer. Client confidentiality meansthe firm cant name which companies

are experimenting with the system, butZeroshift is expecting at least one of themanufacturers to make its involvement withthe company public before the end of 2011.

WHTS WRONG

WITH DUL-CLUTCH

GERBOX INSTED?

There is, of course, one bike already on themarket that offers many of the advantages

of a seamless-shift gearbox Hondas dual-clutch, semi-automatic VFR1200F.

The dual-clutch box is derived fromsimilar systems that are already provingpopular in cars. It is effectively like havingtwo gearboxes. The first has its own clutchand deals with 1st, 3rd and 5th gears. Thesecond, again with its own clutch, deals with2nd, 4th and 6th. That way two gears can b eengaged simultaneously and shifts up ordown the box are done by disengaging oneclutch and engaging the other.

Sounds simple(ish), but it does add afair bit of complexity, including the need

for hydraulics to actually shift the gearsand some very sophisticated electronicsto make the transition between the twoclutches as seamless as possible.

While it works, and works well, Hondahasnt been able to transfer its dual-clutch transmission to MotoGP thanks toregulations specifically banning the use ofdual-clutch gearboxes. They dont, however,ban seamless-shift transmissions. Thatinstantly gives Zeroshift an advantage, butso does the relative simplicity of its system.

Mescall says: A lot of manufacturers the fact its not too dissimilar to a standagearbox. Its not completely unknownterritory. It uses the same manufacturinprinciples, the same actuation principlesand the same assembly principles.Manufacturing-wise, it doesnt deviate frstandard production methods.

Riders may well feel the same way.Zeroshifts ability to provide seamlessshifts while still having the option of beinmechanically operated you can still usefoot lever, physically shifting the gear dr

just as on a conventional bike, and you ca

still use a conventional clutch might givit another advantage: that of familiarity.Its clear that whatever seamless-shifttransmission Honda is using in MotoGP, operated just like a normal transmissionadding fuel to the speculation that theremay even be some Zeroshift internals hidinside those HRC cases.

With announcements about productionZeroshift machines expected before the of the year, its unlikely Hondas secret wremain under wraps for very long.

One of the major benefits is that not only is it seamless onan upshift, for acceleration, but also during a downshift

Neutral selected, with first gear about

to be engaged

All three bullet teeth now meshed with

first gear

Drive continues to first gear as the

bullet starts to move in readiness for

the second gear selection

Bullet has now reached second gear ring,

however drive continues to be transferred

to first gear

Second gear has now been fully engaged

with first gear bullet now merging into

second gear ring

First gear has been fully disengaged, wit

second gear now transmitting all the pow

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2

Main: The componevery similar to a standard ge

1. Stoners Honda has b

revelation with the gearbox techn2. A digital diagram sh

first gear on the left, second on the

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