×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

So what ever happened to this transmission?

So what ever happened to this transmission?

RE: So what ever happened to this transmission?

The stated window for time to market of 3..5 years has not quite expired yet, so maybe they're having, uh, development problems.

... which would not be surprising. I recall seeing section drawings of at least a hundred similar tilting-ball CVTs, few of which got very far past the first prototype. I'd guess that durability issues associated with contact stresses did them in.

Contrast that with the (VW?) steel belt CVT, the first one good for more than a few miles of use, and AFAIK the basis for most/all current production CVTs.

Mike Halloran
Pembroke Pines, FL, USA

RE: So what ever happened to this transmission?

"It will be late in this decade before the product is introduced to the heavy-duty truck market"

Previous versions of this have failed at the contact point between the rotors and the ball or wheel. If you can solve that then they work quite well - low power ones are used in some electric motor transmissions for industrial installations.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: So what ever happened to this transmission?

Primemovers are actually a good market for novel transmissions, since historically they have been plug and play so far as engines and transmissions go. So if this unit doesn't work out it is no great trauma for the owner to replace it with a standard unit.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: So what ever happened to this transmission?

(OP)
I will never understand how anyone with any understanding of torque transfer would even try to design something to transfer many hundreds ft/lbs of torque on such an infinitesimal small contact point that also has close to zero friction ie no teeth to engage and bathed in a lubricant. The pressures involved would have to be in the thousands of tons range for it to even come close to working a little bit. This is one of those typical designed on a computer cad system deals that looks real cute and that is about it. And gee didn't we already have a cvt of sorts the day the torque converter was designed? Lose the belts and the balls, minds well have the slush its simpler.


Edit I remove "and" after Gee.

RE: So what ever happened to this transmission?

Well, I drove the Perbury box in 1981, long before CAD became commonplace. That was a very similar concept.

It's like the wankel engine, it seems to have some significant benefits but has one major point of difficulty. Solve that and you are quids in.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: So what ever happened to this transmission?

I think the reason Allison was interested in this CVT design is for use as a variable speed drive for automotive superchargers or engine driven accessories. It's compact and efficient, but it does not have the capability to scale up well to the torque levels required for most auto/truck transmission applications.

RE: So what ever happened to this transmission?

there are some more of these types of transmission around and none has actually it made to the market yet in big numbers. the great idea behind it all is to have a large range of transmission rations within a small space and with very little slip or frictional losses. in practice that yet is still very difficult if not impossible to achieve.

durability is the main problem, and also lack of suitable lubricants for this specific purpose. the power transmitting balls need to be lubricated to prevent excessive friction and at the same time when torque needs to be transferred the lubricant more or less needs to freeze in place stopping momentarily when the lubricated mating parts need not move relatively to each other. that calls for a socalled traction fluid where the viscosity temporarily can go very high if enough pressure is applied.

various oil companies work on developing suitable fluids, with only limited success so far. for the Nuvinci bicycle drive a naphthenic oil is used - the viscosity rises quite a bit more then with the paraffinic or synthetic baseoils used in most modern lubricants when pressure is applied.

RE: So what ever happened to this transmission?

I think Fallbrook has done a fairly decent job with their CVT for engine driven accessories. For these applications it has satisfactory ratio range, efficiency and durability. The only issues that have not been fully resolved are cost vs. benefit, and added complexity.

Valvoline partnered with Fallbrook to develop a traction fluid (Invaritorc 638) specifically for their small CVT drives.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

White Paper - How ESI is Helping Move New Medical Device Product to Market Quicker & More Cost Effic
Early Supplier Involvement has long been a strategy employed by manufacturers to produce innovative products. Now, it almost seems like a necessity. Because decisions made in the design phase can positively affect product quality and costs, this can help add value to OEM bottom lines. This white paper will discuss many facets of ESI, including why it’s so valuable today, what challenges limit the benefits of ESI, how cost is impacted, and more. Download Now
White Paper - Moving to a Driverless Future
This white paper describes what we see as the best practices to support a sustainable engineering process for autonomous vehicle design. It exposes how to use simulation and testing in common frameworks to enable design exploration, verification and validation for the development of autonomous cars at a system, software and full-vehicle level to drive a mature product development process for automated driving. Download Now
Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close