Tesla finds a solution to transmission troubles
The team at Tesla Motors has been hard at work attempting to prove that they can deliver a performance-minded electric vehicle to the world, but along the way they've hit a few bumps in the road. On top of recent organizational changes, one of the major hold ups on delivering the Roadster has been transmission issues. Their initial thought is to build the first production run with temporary single-speed boxes that will not live up to the proposed performance numbers, then modify the delivered cars once a solution arrives. Now it looks like the road ahead is getting smoother. It turns out that early adopters might not have too long to wait before they get their hands on the real Roadster. Tesla is reporting that through research and development of the WhiteStar sedan they happened to run across a solution for the drop top. They are dubbing it DriveTrain 1.5 and it should be submitted to testing next week.
DriveTrain 1.5 doesn't appear to be an easy fix, as it involves replacing the Roadster's entire powertrain. The electric motor is to be changed from an air-cooled motor to a more powerful liquid cooled unit and the power electronics will also be altered to supply the necessary increased current flow to the new motor. This adjustment will allow for the use of a single-speed transmission with a reduced gear design. The transmission is being developed and produced with the assistance of engineering firm Ricardo, which produces, among other things, the Bugatti Veyron's dual clutch gearbox.
[Source: Tesla via Autoblog Green]
Reader Comments (Page 1 of 2)
Jared 9:00AM (1/24/2008)
Let's see if I've got the scorecard correct.
Plan A: 2-speed transmission from vendor 1. Fails.
Plan B: 2-speed transmission from vendor 2. Fails.
Plan C: "Interim" 1-speed transmission and 2-speed transmission from either vendor 3 or 4. Fails.
Plan D: Reduction gear and different motor cooling.
Explain to me, again, why I should believe anything that Tesla says?
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993C4S 9:07AM (1/24/2008)
Because George Clooney believes them :-)
Sorry, couldn't resist.
http://www.993C4S.com/wordpress
Mobius_1 9:42AM (1/24/2008)
Looking through the posts tagged with Tesla, I can't agree more with Jared. First it's the Tesla EV "Supercar", then a bunch of unveilings, then some valid prototypes, then it all goes downhill from there: reduced range, fired CEO, transmission problems... sigh, I thought I had seen the future, but the future is still far away.
Quattrofan 10:39AM (1/24/2008)
Exactomundo! If I was one of the people with a deposit on this thing, I'd ask for my money back. Too bad.
Dad 9:12AM (1/24/2008)
Who sells a half baked solution and then calls that a victory?
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Mobius_1 9:37AM (1/24/2008)
Just coming over from Engadget, I can't help but to say Microsoft and Apple
Don't flame me, fanboys
Travis Rassat 9:47AM (1/24/2008)
There are a lot of "half baked" solutions out on the road today. Many compromises are made because of costs, production issues, etc. We just don't hear about them because companies aren't normally quite as open as Tesla. What you don't know won't hurt you...
Drew 10:09AM (1/24/2008)
How hard can it be to build a two speed transmission?
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RP 1:16PM (1/24/2008)
I was reading about this...
The transmission has 2 gears, one good for ~60 mph, the other good for 125 mph. The electric motor revs to 13,000 rpm.
The problem comes at the shift, when the engine must quickly spin down from 13,000 rpm to 6,500 rpm. The motor has a lot of momentum, which must be quickly dumped somehow. Either the transmission must absorb the shock, or the motor will dump a surge of current back into the electrical system and batteries as it is decelerated. (I think this is true.)
Anyway, they end up needing a state-of-the-art transmission that has almost race-car type performance (very high RPM, lots of stress). Compounding the problem is that they're trying to do it with just 2 gears (to save cost, probably), vs. having 4+ gears with a closer ratio spacing.
One solution would be a fluid coupling or wet clutch. Another might be more gears, or just 1 gear (with less 0-60 performance).
David Thompson 4:20PM (1/24/2008)
Slipper clutch. This is exactly what they're made for.
Sean Morris 10:46AM (1/24/2008)
I know of electric powered RC cars that have two speed transmissions.
Tesla is just another one to add to the list of "garage" built specialty cars that never comes though. Big promises , small or no delivery on the promises.
Electricity is still not the answer to the question. Its just moving it to the left slightly.
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KarlInSanDiego 11:30AM (1/24/2008)
To those who say, "How hard is it to build a 2 speed transmission?", you're allowing for perpetuation of current design or that this shop hired scads of engineer's and technicians to design and machine their mechanicals. That's not really practical for a startup. Yes, a 2 speed could be made that could take the full torque of their motor while not decelerating said motor before shifting (sic) which was their intention. I'm not sure why you'd call their new unit a transmission, or a transaxle (more appropriately) if it's a one speed and you can run the motor backwards. At that point it's usually referred to as a differential, unless they have a specific need for a reverse gear. Either way, it's the more eloquent solution (no meshing gears to grind/break, no solanoids to shift it for you, no electronics or mechanicals to allow/require you to shift). The downside I see is that they likely had that 2-speed design to bridge performance with efficiency. This new compromise of a single-drive-ratio-solution may require a bigger lith-ion battery to meet their advertised range. Or they'll take the low road and claim the advertised range only counts with a tailwind, downhill, at 37.6 mph.
why not the LS2/LS7? 12:11PM (1/24/2008)
Eberhard was right I guess.
But this company seem like they're in a weird spot. Changing the motor now?
Perhaps the good news is it might do better as a track car now that it has a liquid cooled motor.
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Turbofrog 12:34PM (1/24/2008)
Considering the incredible amount of (very successful) development they had on their existing motor, this strikes me as a very bad idea if they want to get their product out to customers sooner rather than later.
Once Eberhard was fired, things definitely went downhill fast.
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RP 1:19PM (1/24/2008)
Does anyone know why they had to change the motor? Were there problems with the air-cooled motor getting too hot?
why not the LS2/LS7? 2:40PM (1/24/2008)
http://www.autobloggreen.com/2007/12/29/would-the-tesla-roadster-be-a-suitable-track-car/
Yeah, apparently it overheats right now and has to reduce performance.
ronnie schreiber 2:50PM (1/24/2008)
Eberhard wasn't fired. He's still with the company as President.
By the same token, you could say that FoMoCo "fired" Billy Ford when they brought in Mullaly as CEO. Billy gave up the CEO position but remains Chairman of the company.
Eberhard is an engineer. As they approach launch they need a business person to run the business.
Also, I'd like to ask all the critics who keep badmouthing Tesla (and no, I have no vested interest in Tesla) if they have any experience designing, producing and selling a simple product, let alone something as complicated as a car, particularly one involving new technology?
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Jared 4:06PM (1/24/2008)
Ronnie, you are completely wrong. Eberhard was fired. He's no longer with the company. He's not president. The president is Ze'ev Drori: http://www.teslamotors.com/media/company_team.php.
Eberhard said: "Yes it is true - I am no longer with Tesla Motors - neither on its Board of Directors nor an employee of any sort. I have also signed a non-disparagement agreement with Tesla, so I must. by contract, be a bit careful about how I word things."
TheRaven 7:33PM (1/24/2008)
Thanks Jared....looks like someone got OWNED.
ronnie schreiber 7:59PM (1/24/2008)
Jared, thanks for the correction. I was basing my statement on the original announcement which said that Eberhard was staying on as president of technology.
As for the bird, it's sad that some people have so little going on that they have to be fanboys for critical comments made about third parties. Boy it must make you feel really good about your anonymous self to say that he OWNED or P3NED someone who posts under their real name. Talk about vicarious enjoyment.
Raven, I have no problem admitting my mistakes. I'd call you a putz but putzes have a purpose.