As we've reported before, Nissan is committed to the continuously variable transmission (CVT) for use in passenger cars due to the environmental improvements that the alternative transmission's enhanced efficiency allows. CVT transmissions are not locked into set gear ratios, instead they can offer any ratio which falls in between their minimum and maximum values as defined by multiple internal pulleys or planetary gearsets. In 2007, Nissan surpassed its stated goal of selling a million CVT transmission units in passenger cars by selling 1,088,000 in total, just less than thirty percent of its total global sales. In North America and Japan, though, the CVT represents almost half of Nissan's total transmission output.

Just how much good are Nissan's CVT's for the environment? Nissan's data suggests that a million cars equipped with CVT's is equal to the carbon reduction of 200,000 hybrids -- many of which use CVT transmissions as it is.

[Source: Just-Auto - sub. req'd]

Is it solely a case of one-upmanship that is driving the number of forward gear ratios forward in today's passenger cars? Or, are consumers choosing vehicles based on the number of gears in the transmission? I am not entirely sure, but I do know that I would consider passing on a vehicle just because it only has a four-speed transmission. As rare as they are today, some vehicles, like the GM full-size pickups, are still using four-speed automatic transmissions. Before you comment, I know that they are being phased out in favor of the new six-speeders. But, a little research shows that Mercedes and BMW offer seven speed automatics, and Lexus has an eight speed for their top-of-the-line model. Why so many gears? Efficiency is one reason, and performance is the other. We'll start with the latter.

Do you remember the old Power-Glide trannys that GM used when muscle cars were just hitting the scene? I'm not old enough to remember, but I have experienced them after-the-fact. They worked fine, but if you were cruising in second gear and hit the gas causing a downshift, it might be rather abrupt, because there was only one choice for the transmission to make. In the newer trannys with more gears, there are many choices. For instance, imagine cruising in gear eight, you hit the gas ... depending on how hard and at what speed you are traveling, you could drop to seventh for a gradual acceleration, or to fourth for fast pick-up. Conversely, only having two forward gears in the Power-Glide allows for excellent reliability and it also makes them predictable, which is why they are still popular transmissions for drag racing.

Now, as far as efficiency is concerned, if you are driving slowly, the transmission can up-shift to a lower numeric gear ratio, saving gas in the process. I have never driven a car with more than six forward gears ... so I can't say what the driving experience is like, but it is certainly a market trend to increase the number of forward gears. For maximum efficiency, a manufacturer may choose a CVT with an infinite number of ratios, but some consumers don't like the driving experience with them. So I would expect to see more and more new transmissions like this ZF with eight forward gears. The more the merrier?

[Source: Gizmag]

Not too long ago we showed you a new automatic transmission that has been developed with bicycles in mind, but may very well be suitable for larger-scale machines such as motorcycles or even automobiles in the future. The transmission is now available on the Ellsworth Ride city bike. We have also shown you how you could potentially save time by commuting on a bicycle, depending on the traffic patterns in the area in which you live. Granted, this is a very expensive bicycle ($3,000-$4,000), but think of the bright side: not only will you have no emissions when you ride (in style), but you will also be helping your own body.

[Source: Ellsworth via Gizmag]

Now this is something that is totally cool. You are probably familiar with the CVT, or continuously variable transmissions, that are becoming more commonplace on modern cars and scooters these days. The systems generally use a couple of pulleys and a belt or chain to connect the two pulleys. As the diameter of the pulleys change, the belt and output shaft change speeds, allowing the car or scooter a seamless transmission from high to low "gear".

This is another type of CVT, one that uses a planetary setup instead of the more common pulleys and belt. Watch the video above the some technical details on how it works. This invention could prove less costly to manufacture and could be more durable than current CVT's, and may see use in everything from bicycles to cars.

[Source: Youtube via Hugg]

Canadian gearing technology company Ikona Gear International announced that they have filed for two provisional patents that will help automakers produce more efficient and environmentally friendly vehicles - a frictionless CVT clutch and frictionless CVT differential.

Ikona says that the frictionless clutch can either replace a standard clutch mounted to a manual transmission or the torque converter on a hybrid. They make no mention of replacing torque converters on standard gas-powered automatics, but perhaps that's only to stress the energy-saving possibilities of their new technology.

Other than defining a continuously variable transmission as "an automatic transmission that can change the 'gear ratio' to any arbitrary setting within designed limitations," the press release doesn't discuss the underlying technology, nor I wasn't able to find any additional information. Now, a clutch essentially does two things. The first is to control the desired amount of slip (which can almost be thought of as continuously variable gearing) in which it acts much like a CVT. The second, however, I have yet to wrap my head around - how do they achieve complete disengagement?

As for energy savings, beyond stating that the frictionless technology allows for the recuperation of energy normally lost to heat, Ikona doesn't speculate just how much energy can potentially be saved overall. You can bet we're eager to hear forthcoming estimates and more about the technology in general.

You can read the entire press release after the jump...

[Source: Ikona Gear International]