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View Full Version : The future of the gearbox?



jameswithington
02-01-2004, 08:37 PM
I've read a few little bits here and there about a system in development in the UK called "Zeroshift". It's basically being designed and built by one guy with some help from his mate, so nobody is allowed to release technical details of how it works to keep any of the big companies from trying to steal their ideas. The idea is to create a totally clutchless manual shift which gives absolutely no break in the power delivery (ie the 'holy grail' for transmission designers). It seems to work without any electro/hydraulic intervention, making it relatively simple and reliable, and it seems to be applicable to standard H-pattern 'boxes, as the guy is tesing it in his own TVR Cerbera's Borg-Warner 5 speed unit. Obviously we'll have to wait and see if it really delivers on its promises, but some of the readout data from testing seems to prove that there is no break in power.

I know there've been numerous attempts to speed up the time between shifts (Audi's DSG, BMW's SMG), but so far even the millions of pounds thrown around by the big F1 teams hasn't been able to find a definitive solution that gives absolutely no break in torque. Wouldn't it be nice if some bloke working in his garage managed to beat the big bucks corporations to the punch!

Go to www.pistonheads.com/tvr/default.asp?storyId=7929 for some more info, and follow the link at the bottom for the .pdf copy of a Racecar Engineering magazine article which prints some of the test readout data. Very interesting stuff, I'm sure you'd all agree!

DodgeNitroBIRM
02-02-2004, 12:12 AM
I still don't know how that would work. How would you start it without stalling the motor?

Matra et Alpine
02-02-2004, 02:43 AM
I've read a few little bits here and there about a system in development in the UK called "Zeroshift".
It might be the appliaction of older ideas but now with better material and more accurate manufacturing it may have more 'life'.
It's common to 'crash' a box in competition esp rallying on the way up - time to change doesn't really matter on the way down. So it may be that it's a better design of dog or cones in the gear engagement.
Or it may be pre-selection. Audi used this in the last of the GrB supercars. VERY complex gearbox design and expensive, but CAD and CAM could have made this all easyier today.
Typical Britain - millions spent in engineering at it's pinnacle and a couple of guys in a shed say they've saolved the worlds major engineering challenges. Bet you the American manufacture it first and the Japanese companies make it better :)

ajmcgarry
02-02-2004, 06:19 AM
I still don't know how that would work. How would you start it without stalling the motor?

The article does say
"The 'Zeroshift' gearbox is a new 'box that promises clutchless upshifts just by slamming from one gear into the next without even lifting off the power"

it does not mention engagement of the first gear, although I suppose this could be done similar to a regular automatic box or with a manual clutch.

ajmcgarry
02-02-2004, 09:14 AM
it does not mention engagement of the first gear, although I suppose this could be done similar to a regular automatic box or with a manual clutch.


Then again the full article does say that no clutches are employed.
Maybe they are using some sort of torque slip for first gear at low revs.
I guess we will have to wait and see......

Bear87G
02-02-2004, 01:34 PM
In a quote from the article and my prior impression I assume that the gearbox does contain a conventional clutch but only for getting the beast going.

"Quite simply the driver dumps the clutch and accelerates under full power then, as the red line looms he moves the lever into the next gear."

Otherwise amazingly enough it is able to basically be in two gears at once. Thinking along this kind of mechanism you realise this is exactly the kind of thing a bike does (the article states that the engineer involved studied extensively the bike derailluer (spelling) design before moving to automotive design). The derailluer actually moves the chain onto a different gear while it is also partially on the previous gear.

This fact makes me wonder if this "bike" design will be used in conjuction with other automotive usual function to create the Zeroshift gearbox.

Bear

Matra sent you a message.

crisis
02-02-2004, 11:31 PM
The gearbox in the Honda HRV is similar in that it changes gears on the run although this is done automatically. I can imagine how this process could lend itself to a manual change.

Matra et Alpine
02-03-2004, 02:59 AM
The gearbox in the Honda HRV is similar in that it changes gears on the run although this is done automatically. I can imagine how this process could lend itself to a manual change.
I believe in the UK the HR-V uses Continuously Variable Transmission (CVT).
This is a modern implementatino of the DAF vario-matic transmission.
In this their are two wheels joined by a belt.
Each wheel can vary in size.
So for low gears the driving wheel is small and the driven wheel large. So engine speed is translated to a lower road speed. For high gears the driving wheel is large and the driven wheel small so gicing high road speed.
The point is that both wheels are V-shaped and sizes are changed by 'squeezing' them. so their is no real gearchange. They're odd to drive as with NO fixed gear change, when you press the throttle the engine revs to peak power and the car then speeds up - the revs don't change !
It was found this confuses most folks so modern interpretations use the computer to simulate gear changes - so the wheels are maintained at one size while the revs rise and then at a certain speed they are both changed for the next 'size' up/down.
From this it's easy to give the 'user' control over how the gearbox works. You can have lazy gearchange points for street and 'fast' ones for track. All under the control of the driver :) Paddle changes are easy - only another set of settings for the wheels to change under control.
UNFORTUNATELY, it's not a great system for transferring lots of torque or power as the belts can slip :(
It would be possible to 'program' the CVT to 'act' like a 5, 6 or 7 speed box.
In reality doing that makes the car slower and less efficient. The win with CVT is the engine revs can be maintained at the peak power ( or peak efficiencey ) and the transmission does all the work. When we get the materials right it's a winner.