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 Post subject: how does a CVT work?
 Post Posted: Mon Dec 08, 2008 2:53 am 
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Empress Diva
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Joined: Mon Sep 10, 2007 3:30 pm
Posts: 1048
Location: Nederland, Colorado
Scooter: SYM HD200
Does anyone have a good explanation of what happens and what parts are in a CVT? I hear about weights and sliders, and there's springs but I've just got no grasp on what the weights do. pictures?

I'm thinking that if I understand how a CVT works then I can learn how to eek more power out while going up really long hills (which always feel like its sliding out of it power band and I could just 'down shift' I wouldn't lose so much speed.)

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winds blow past my face ... a waking dream of summer ... blue scooter sleep well


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 Post subject: Re: how does a CVT work?
 Post Posted: Mon Dec 08, 2008 7:56 am 
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Queen Diva
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Posts: 546
Location: State College, PA
Scooter: Bo - 2007 Vespa GT200 in Midnight Blue (r.i.p.)
??? - 2012 Vespa GTS 300 in Titanium
Why do you want to join this forum?: live to scoot - scoot to smile.
This is a REALLY good question! One that I can't wait to hear the answer. I get that same feeling of wanting to be able to down shift, or pop it into neutral at times. You're right, understanding how it works might help.

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 Post subject: Re: how does a CVT work?
 Post Posted: Mon Dec 08, 2008 8:06 am 
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Admin Diva
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Courtesy of Fly Scooters
How CVT Works


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 Post subject: Re: how does a CVT work?
 Post Posted: Tue Dec 09, 2008 1:19 am 
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Empress Diva
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Joined: Mon Sep 10, 2007 3:30 pm
Posts: 1048
Location: Nederland, Colorado
Scooter: SYM HD200
I found these videos to be helpful - please add to this! There's a lot of vocabulary to wrap one's head around. (I feel like I'm back in school and writing a lesson at the same time)

A nice walk around of what makes a scooter go. "How Scooters Work by Jessica"
http://www.youtube.com/watch?v=k5tErEP70rs&feature=related

At 4minutes :30seconds, she talks about the CVT (Constant Variable Transmission). Ah ha! A CVT has a variator (the 'disc' on left in photo below), a clutch (the 'discs' on the right), and a belt which connects the two together.
Image

Inside the variator are rollers which are also called weights. As the variator spins, the rollers move outwards to the edges of the disc. This makes the belt move outward which changes the power ratio. As this happens, the clutch also engages, spreading the cluth discs apart which makes the belt moves downward (inward). See the video that Ellen suggested a good description on how the power ratios change.
Image

Now those rollers can be replaced by what is called a sliding rollers (or sliders). This advertisement shows what they look like:
Image
http://www.youtube.com/watch?v=IyuC-LQE6Vk

And to see what it takes to replace them, see this video
http://www.youtube.com/watch?v=hyb9NyR-Sjs&feature=related

Another explanation that also works: http://motorscootermuse.com/stepless.php

Now the challenge is how to get max torque when you're already going... like for uphills. There's probably some technique that helps get some umph that is similar to downshifting a manual transmission.

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winds blow past my face ... a waking dream of summer ... blue scooter sleep well


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 Post subject: Re: how does a CVT work?
 Post Posted: Tue Dec 09, 2008 8:55 am 
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Super Diva
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Joined: Mon Nov 19, 2007 10:50 am
Posts: 188
Location: Ohio
Scooter: Vespas
Thanks for the lesson! I've never been able to wrap my brain around that concept until now!

I'd go to a maintenance workshop weekend in a heartbeat if I could find one. Any Divas interested in putting one together? That would be great!


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 Post subject: Re: how does a CVT work?
 Post Posted: Tue Dec 09, 2008 11:21 am 
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Queen Diva
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Joined: Wed Jul 09, 2008 1:43 pm
Posts: 546
Location: State College, PA
Scooter: Bo - 2007 Vespa GT200 in Midnight Blue (r.i.p.)
??? - 2012 Vespa GTS 300 in Titanium
Why do you want to join this forum?: live to scoot - scoot to smile.
awesome thread. thanks everybody for posting!

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-- kim
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