Automakers in the US have a troubling goal ahead of them; they need to reach an average 54.5 mpg for all products sold here, by 2025. With only so much economy left to be squeezed out of growing technologies like cylinder-deactivation and direct injection, the Continuously-Variable Transmission holds a lot of promise.
That is why, Wards Auto reports, General Motors is in the late stages of developing an in-house CVT.
Powertrain Spokesman Tom Read could not confirm that much to Wards, but the automaker has already hosted suppliers at its Global Powertrain Headquarters to discuss parts-sourcing.
CVTs hold promise for delivering better fuel economy because, as their name implies, there are no gears, or “steps,” from vehicle launch to top speed. Instead, the drive ratio between the engine and the driven wheels is infinitely variable until it reaches its maximum.
However, CVTs aren’t without their drawbacks; when General Motors embraced the technology earlier in the millennium, the automaker eventually encountered both issues with production, and drivability problems. They ended up phasing out the in-house CVT, and offer only a Japan-sourced unit in the Spark. The City Express commercial van offers one, too.
But, says Spokesman Read, “GM has unmatched transmission expertise and development resources and is capable of delivering additional CVTs if and when they’re needed.”
Comments
This comment is for Tom Read at GM and/or any other interested party.
Your quest for a viable CVT starts with viewing the website indicated above and clicking on the pages (2) that bear my name.
I will be looking forward to hearing from you.
J P
This comment is for Tom Read of GM and /or any other interested party.
Your search for a ‘viable’ CVT begins with viewing the website shown above.
I will be looking forward to hearing from you.
J P
I’m glad I’ll be dead when these rubber band transmissions will become mainstream.
The common planatary gearset can be the base for a simple CVT with no pulleys or belts. Ask any mechanical engineer.
I have yet to find a CVT that even remotely provides the drivability a fixed gear transmission does. While perhaps cheaper to produce than the new to market 8 and 9 speed trannies we see from automakers, once the teething/software issues are sorted I believe these will not only prove to be better dynamically, but geared right, will produce better average economy.
Here is s question for you guys who have more experience with CVT’s. Where do you find you don’t measure up fuel economy wise? For an example, I’ve had a chance to drive the new Corolla in 4-spd auto as well as CVT (neither car beat my older Cruze I gotta say). I found the CVT optioned Corolla noisier as well as my highway economy less than the traditional 4-spd. I often noticed (perhaps because where I live there is substantial elevation change) I seemed to frequently run at lower RPM’s with the slush box than the CVT.
I don’t know, and I’ve got no expertise nor ego in this, but it feels like to me that the CVT is tailored made for US fuel economy testing, but in real world driving, they feel inferior (to me) when compared to fixed ratio transmissions.
Ironically enough, the only example here where I can argue with myself are the GM CVT transmission that incorporated fixed gear ratios. In Seattle, our buses use the commercial version of those transmissions with great success, and you can tell when it’s working as a CVT in light load, versus fixed gearing in heavier loads.
Anyways, thanks for letting me ramble on here guys!