Continuously Variable Transmission?

Being a new guy here, not only am I new, I don't know jackshit about cars (maybe a little, but that's it). What is CVT (continuosly variable transmission)?

All replies are appreciated!

  Motorhead

Ok, I'll try to cover this one. But before we talk CVT, we need to look at a regular transmission.

These come in various gear choices from a 3 speed (gear) transmission to a 6 speed (gear) transmission (usually). Take the 3 speed. You have 3 gears to use from 0 to 65 MPH (keeping it legal). First gear takes you from 0 to 20, 2nd from 20 to 50, and 3rd from 50 on up.

When your in each gear, the engine is opperating at peak performance and lowest emmisions (not necessarily at the same time) during only a small amount of the MPH range. Say in first gear from 10 to 12 MPH. During the rest of the time ( 0 to 10 and 13 to 20MPH) the engine is not operating as effeciently. The car manufacturers try to select their gears based on engine performance specs and final drive characteristics of the vehicle.

Now wouldn't it be cool if you could put as many gears in the transmission as you wanted to keep the engine opperating in the small range where perfomance and emmisions are optimized? Well in a way, that is what a CVT does. No, it does not have 30 gears in there, instead it has 2 opposing cones (points facing inwards) and a belt (steel reinforced) that transfers the power from the engine to the wheels. It opperates similar to a snowmobile drive system.

The main purpose of a CVT is to keep the engine opperating at optimal levels. When you drive one, you will not feel the car shifting (unless you are in a model with the shift feedback mode) and if you watch the tach you will notice very little movement as you accelerate.

Hope this helps out. I leave it to you to do some research on the web to look into the details of the design. There should be a bunch of pictures out there to help you get a grasp of the concept. Good luck.

Keith

  theman352001

Thank you for the excellent reply. It's nice to have some qualified help answering technical questions. I was feeling like the Lone Ranger.

  vwhobo

Yes it did help alot, thank you

  Motorhead

I was trying to keep it short. Glad it helped out.

vwhobo - Thanks for the kind words. "Qualified help" huh? hope I live up to it.

  theman352001

Looks like summer's over... :P
"Hunt for missing CF Members halted"

  Unfedfat

Unfedfat Posted: 08.20.2003 3:03 AM

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Looks like summer's over...
"Hunt for missing CF Members halted


See, now I wasn't going to mention that I "might as well answer this question so admin doesn't threaten to kick me out". :P It goes to show though that.........THEY ARE WATCHING....... 8O

PS: I didn't know I was lost. Thanks for finding me. :D

  theman352001

Excellent answer for the CVT...I worked for Nissan for a while and was constantly having to explain it when the Murano was released...And now I hear Audi's going to throw down and bring a CVT in the S4 convertible...
:evil:

  Machine

So, are CVT's very good for performance applications?

  Widowmaker2k

They may be in the future but with the current level of technology they're either too weak or too heavy. And the remedy for those two ailments equals too expensive.

  vwhobo

Posted: 08.21.2003 7:11 AM

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So, are CVT's very good for performance applications?

Theoretically, yes. They were initially designed to help vehicles meet emmisions standards by keeping the engine running in its most efficient state (RPM/load characteristics). But the transmission could be configured to keep the engine producing maximum HP or maximum torque or even go from max torque during take off to max HP at speed. I wouldn't doubt in the future that the trans could be as programable as your engine opperating system.

As vwhobo stated though, they are not at that point yet.

  theman352001