CVT's (constantly variable tranny's)
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CVT's (constantly variable tranny's)
what do you guys think about these? instead of the normal gears running off of the hydrolic pressure they put in a drivebelt system on 2 diffrent pullies that run off of the pressure....only on automatics though that i know of....
good or bad? race-able or not?
good or bad? race-able or not?
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The only problem with these transmission is that they don't handle high power application due to the belt pulley design. The transmission however is very impressive from a typical consumer standpoint if you have ever driven a CVT equiped vehicle.
What looks promising for high performance applications is the DSG (Direct Shift Gearbox) made by VW/Audi. This automatic transmission can shift gears ~0.0 secs and by design handle high performance applications with the use of two conventional gearboxes and a computer controllering the shifting and clutch.
What looks promising for high performance applications is the DSG (Direct Shift Gearbox) made by VW/Audi. This automatic transmission can shift gears ~0.0 secs and by design handle high performance applications with the use of two conventional gearboxes and a computer controllering the shifting and clutch.
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Originally posted by lstepnio
What looks promising for high performance applications is the DSG (Direct Shift Gearbox) made by VW/Audi. This automatic transmission can shift gears ~0.0 secs and by design handle high performance applications with the use of two conventional gearboxes and a computer controllering the shifting and clutch.
What looks promising for high performance applications is the DSG (Direct Shift Gearbox) made by VW/Audi. This automatic transmission can shift gears ~0.0 secs and by design handle high performance applications with the use of two conventional gearboxes and a computer controllering the shifting and clutch.
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Originally posted by lstepnio
The only problem with these transmission is that they don't handle high power application due to the belt pulley design. The transmission however is very impressive from a typical consumer standpoint if you have ever driven a CVT equiped vehicle.
What looks promising for high performance applications is the DSG (Direct Shift Gearbox) made by VW/Audi. This automatic transmission can shift gears ~0.0 secs and by design handle high performance applications with the use of two conventional gearboxes and a computer controllering the shifting and clutch.
The only problem with these transmission is that they don't handle high power application due to the belt pulley design. The transmission however is very impressive from a typical consumer standpoint if you have ever driven a CVT equiped vehicle.
What looks promising for high performance applications is the DSG (Direct Shift Gearbox) made by VW/Audi. This automatic transmission can shift gears ~0.0 secs and by design handle high performance applications with the use of two conventional gearboxes and a computer controllering the shifting and clutch.
Nissan has been putting the CVT's in heavy commercial trucks for over 10 years now. They don't seem to have a problem with heavy loads or lots of grunt. I believe the fact that noone has truely tested the power handling capabilities of the cvt's we see here in the states is the reason for this conception of not being up to the task.
Also, not sure about the DSG, but audi has put some high hp numbers through their version of CVT's.
And i ask this out of ignorance here, but aren't the "belts" in CVT's actually a chain of sorts? Seems like i remember seeing a Audi cvt opened up at Crown Euro and i could have sworn that "belt" was/is a 4-link(width) chain.
Also, nowhere that i could find did any of the Nissan serice and maintainance cd's did it mention the replacing of a "belt" as a part of maintinance of the tranny. So is an actual rubber belt supposed to last indefinately? If that's the case why the hell can't we get that kind of belt for the rest of the belt applications in out vehicles?
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Here is an image of the CVT belt used by Nissan on the Murano:
Here are some diagrams to give you a better idea of how this simplistic engineering marvel actually works.
Nissan's new Murano SUV uses a steel push belt in its CVT. The belt technology is what makes the high torque transfer possible from Nissan's 3.5 litre V6 engine. The belt is made of a series of small plates held in position by a cable. When torque is applied to the belt as it comes off the drive pulley, the plates lock together so the belt acts as a solid link. As the belt starts to rotate around the driven pulley, there is no more torque on the belt and it becomes flexible again. Imagine trying to push a rope. Every time you push it, it turns into a stick, but pull on it and it becomes a rope again. Sounds like magic. The oil used in this CVT is part of that magic.
Nissan is using a special oil that helps lock the steel belt to the pulleys but it also lubricates and cools the transaxle. The best way to describe the oil is that it contains "rubber molecules" that provides the grip between the belt and the pulleys. As pressure is applied to the oil, the "rubber molecules" compress, turning into a crystalline form that locks the belt and pulley together. Relax the pressure and the oil returns to its original state.
Nissan is using a special oil that helps lock the steel belt to the pulleys but it also lubricates and cools the transaxle. The best way to describe the oil is that it contains "rubber molecules" that provides the grip between the belt and the pulleys. As pressure is applied to the oil, the "rubber molecules" compress, turning into a crystalline form that locks the belt and pulley together. Relax the pressure and the oil returns to its original state.
Last edited by lstepnio; Mar 10, 2004 at 02:36 PM.
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Originally posted by lstepnio
Here is an image of the CVT belt used by Nissan on the Murano:
Here are some diagrams to give you a better idea of how this simplistic engineering marvel actually works.
Here is an image of the CVT belt used by Nissan on the Murano:
Here are some diagrams to give you a better idea of how this simplistic engineering marvel actually works.
Thanks for the informative pics and dialogue. It understand how CVT's work and thier concepts. I guess i just didn't quite conve(sp?) what i was thinking.
By the word belt i meant the design we all are familiar with, you know the rubber kind. The "belts" used in CVT's are in fact more akin to chains. by that i mean metal/steel construction linking together and providing momentum for the vehicle. I guess its i little dificult to pic up on the sarcasm(in a good way) with my dry sense of humor.
Maybe for simplicity sake its marketed as belt driven, but i just haven't made the contection with the word belt in the sense we all know it. It happens to act and have the properties of a chain in my mind. Since you brought up Audi maybe you have a photo on file of what i saw all spread out in the service bay at Crown. I can't remember what car it was out of. I'll see if i can locate what i'm talking about.
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that style of pulley/belt set is/has been used in scooters i.e honda areo ( from the 80's) and such...not a new concept by any means at all, but cool non the less
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