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Regztfen 12-03-2008 06:40 PM

Cvt
 
First, I know absolutely NOTHING about an automobile. But after reading some of these posts, I have a question. If the CVT transmission of the TCH is so efficient why isn't it found on all cars and not just the hybrid?

Al Froio 12-03-2008 06:55 PM

Re: Cvt
 
Because the CVT in the TCH is not like a conventional CVT, it is a power splitting device or PSD. Many CVTs use a system of belts and cones to vary the speed ratio of the engine to the front wheels. The PSD uses a different system which is explained on this web site

http://eahart.com/prius/psd/

Regztfen 12-03-2008 07:19 PM

Re: Cvt
 
Then why aren't the conventional CVT's used in other cars?

GreenRedTCH 12-04-2008 12:14 AM

Re: Cvt
 
Actually they are used in a few other cars. The Nissan Altima non-hybrid uses one. And the old Honda Civic HX used to use one. The reason they are not very common is because they can't handle very much torque (this is the conventional CVT not the Toyota PSD system which can handle lots of torque). I understand they are working on this problem though.

ymiheere 12-04-2008 05:10 AM

Re: Cvt
 

Originally Posted by Regztfen (Post 192686)
Then why aren't the conventional CVT's used in other cars?

I believe it is just a matter of economics - for now at least the CVT's cost more. They are, however, infinitely smoother!!

Also, there is the torque factor as mentioned earlier by GreenRedTCH

wwest 12-04-2008 09:56 AM

Re: Cvt
 
"They are, however, infinitely smoother!!"

Along with being more FUEL EFFICIENT when coupled with the newer knock/ping sensors. With this combination the engine can ALWAYS be run right in the CUSP above lugging when in cruise, constant speed, mode.

Al Froio 12-04-2008 01:11 PM

Re: Cvt
 

Originally Posted by Regztfen (Post 192686)
Then why aren't the conventional CVT's used in other cars?


I knew others would join in on this discussion and help me out. As I recall CVTs were first introduced on small cars because of the 'torque' that larger engines on larger cars develop. Many CVTs were driven by belts that a big engine would shred to pieces. CVTs have come a long way since then and now even the Nissan Maxima has a CVT available. As already said CVTs are incredibly smooth and you'll start to see them on more large cars. Your TCH is an amazing machine and you'll learn a lot about it if you spend one hour a night going through the old posts on this website. The TCH was the best value on the market when I bought mine two years ago and I believe it still is. Read you new car guide twice, a month apart, to really understand what you've got. You'll be amazed.

Al Froio 12-04-2008 02:59 PM

Re: Cvt
 

Originally Posted by Al Froio (Post 192771)
I knew others would join in on this discussion and help me out. As I recall CVTs were first introduced on small cars because of the 'torque' that larger engines on larger cars develop. Many CVTs were driven by belts that a big engine would shred to pieces. CVTs have come a long way since then and now even the Nissan Maxima has a CVT available. As already said CVTs are incredibly smooth and you'll start to see them on more large cars. Your TCH is an amazing machine and you'll learn a lot about it if you spend one hour a night going through the old posts on this website. The TCH was the best value on the market when I bought mine two years ago and I believe it still is. Read you new car guide twice, a month apart, to really understand what you've got. You'll be amazed.

For more info about CVTs go to these sites


http://cars.about.com/od/thingsyouneedtoknow/a/CVT.htm
http://auto.howstuffworks.com/cvt3.htm

skoh 12-05-2008 01:49 AM

Re: Cvt
 
The Asian car manufacturers are probably the biggest adopters of CVTs.
- Toyota Super CVT
- Nissan N-CVT
- Nissan Hyper CVT
- Nissan Hyper CVT M6
- Nissan Extronic CVT M6
- Nissan Extroid CVT M6
- Honda Multimatic CVT
- Mitsubishi Motor INVECS-III CVT
- Mitsubishi INVECS-III Sports Mode 6-CVT
- Fuji ECVT
- Fuji Sports Shift ECVT
- Fuji i-CVT
- Fuji Sports Shift i-CVT
- Daihatsu Eco CVT
- Suzuki CVT (ECVT)
- Suzuki CVT (dry composite belt-type CVT)
- Suzuki SCVT

Ford used to have a CVT (made by ZF), as an option to the Ford 500 and Ford FreeStyle. But, it was discontinued.

Chrysler has several vehicles with CVTs (made by Jatco), including the Dodge Caliber, Jeep Patriot, and Jeep Compass.

Frodo 12-05-2008 05:39 PM

Re: Cvt
 

Originally Posted by Regztfen (Post 192686)
Then why aren't the conventional CVT's used in other cars?

The current crop of belt-driven CVTs have a problem with torque capacity and lubricant (if it gets out of its temp range, BAD THINGS HAPPEN, like galling of the pulleys or belt). Nissan puts a 'hack' on the higher-power CVTs where engine power is controlled if over-temp is detected. C&D reported a 3+ mile cool-down cycle between max-power launches.

Likewise, if the trans fluid in a belt-driven CVT isn't right, the pulleys will self-destruct in a relatively short time. The durability of Nissan transmissins isn't too bad these days, but they did have some issues with the early ones.

As others stated, Toyota's HSD is a planetary gearset transmission that doesn't have this sort of limitation or wear point, as the different gear sets in the planetary gearsets are driven by the different motors (the ICE, MG1 and MG2.
The biggest "issue" with the CVT acceptance is in tuning the engine note - if done wrong, it sounds like a extended-note bovine solo from the pastoral symphony;). One of the reasons Toyota put extra sound deadening and extra resonance chambers on the intake in the TCH is to control this tendency. Any CVT will peg the engine RPM to the appropriate value for power demanded, and this monotone note can get annoying. This also leads to silliness like Nissan simulating a 6 speed via 'fixed' ratios in the CVT, accessible via a 'shifter'.


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