innerware Posted October 19, 2003 Share Posted October 19, 2003 Hey all, this isn't Z related but I though there would be people out there that would know. I saw the new Toyota Prius today and it has a continuously variable transmission or something like it. I asked how many gears it had for it's auto( only comes in an automatic) and he said it didn't have any gears. Is this right? He said Nissan has it on there new SUV. What kind of tranny could it be that it doesn't have gears? He also said it didn't have any tranny fluid. Is this like the new BMW's 7 series sealed tranny that I have heard about? Just curious, thanks, Kyle Quote Link to comment Share on other sites More sharing options...
innerware Posted October 19, 2003 Author Share Posted October 19, 2003 O.k. I will answer my own question and post what I found for those that didn't know either. CONTINUOUSLY VARIABLE TRANSMISSION A continuously variable transmission is an automatic that can select any desired drive ratio within its operating range. Unlike a traditional three-, four-, or five-speed automatic transmission, the CVT is an ‘infinite speed’ transmission. It continually selects an optimum overall drive ratio between engine and drive wheels for all operating conditions, whether accelerating or cruising. Unlike conventional automatics, there are no perceptible shifts. During maximum acceleration, the drive ratio is adjusted to maintain peak engine horsepower. At a constant vehicle speed, the ratio is set to maintain an optimum balance of fuel economy and driveability. A CVT provides smooth, fast acceleration and high cruising efficiency with the convenience of an automatic transmission. The most common CVT design uses a segmented metal V-belt running between two pulleys. Each pulley consists of a pair of cones that can be moved close together or further apart to adjust the diameter at which the belt operates. The pulley ratios are electronically controlled to select the best overall drive ratio based on throttle position, vehicle speed and engine speed. CVT systems are commonly in use in Audi’s multitronic, Honda’s MMT and Mitsubishi’s INVECS-III CVT among others. Question? How to put one in a Z? They sound great! Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted October 19, 2003 Share Posted October 19, 2003 CVT's have their limitations. Generally you find them in light, low power vehicles. The segmented belt and variable pulley connection does not transmit high power outputs very well. Slipage causes friction and then heat that causes more slipage and then damage. CVT's, like electric cars, have been around as long as the car. But after a century of many bright minds working on them, both occupy only a tiny fraction of the automotive market. Quote Link to comment Share on other sites More sharing options...
Dp351zcar Posted October 19, 2003 Share Posted October 19, 2003 Snowmobiles(sp?) have had CVT's for years using a rubber type belt. Don Quote Link to comment Share on other sites More sharing options...
baddriver Posted October 21, 2003 Share Posted October 21, 2003 Yes, the variable size pulley and belt system is a common CVT. I had one on my moped, and as mentioned snomobiles used them. I thought that the newer ones were hydraulic, using a torque-converter like setup, but with one disk having variable veins. I don't know how they would do it without tranny fluid, must be some other system. A lawnmower I used as a kid also had a CVT. The drive was a disk, and the driven part was a wheel that rode on the disk. You changed the ratio by moving the wheel in and out on the disk radius. It was a very strange setup, I've never seen anything else like it. It was a weird lawn mower all around, thre wheeled and you could push down on the handle to pick up the front of the mower to get over obstacles. It's probably in the junk yard now. When I worked at John Deere, I heard they were developing one, I think the new lawn tractors have it. But seeing it in a production car is kind of new. If anyone knows how the Prius tranny works, I am dying to know more! Quote Link to comment Share on other sites More sharing options...
Cruez Posted October 21, 2003 Share Posted October 21, 2003 Most automatic ATV's use a CVT also... I can't see it holding much torque for HP applications though.. Quote Link to comment Share on other sites More sharing options...
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