Controlled variable transmissions, or \u201cCTVS,\u201d are gear-free transmissions that are only good because of engine drone under heavy throttle, and they are slowly invading against manuals and conventional automatics, especially in 2014 models.<\/p>\n
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Audi, Honda, Hyundai, Subaru, and Toyota all make their own CVTs. Nissan owns a controlling interest in JATCO, the firm that supplies 49 percent of the world\u2019s gear-free transmissions to Chrysler, GM, Mi\u00adtsu\u00adbishi, and Suzuki. In addition, nearly half of Nissan\u2019s current U.S. models offer a JATCO-supplied CVT. You would think that with all of these major car companies providing a model of this style, there would be a greater market for them. However, it is beginning to seem like this is just another one of those things that can be categorized as a \u201cone hit wonder\u201d in the auto industry.<\/p>\n
To trim parasitic losses in its new \u201cintelligent shifting\u201d CVT, Toyota, for example, designed an engine-driven oil pump with a second discharge port. The low-pressure outlet handles transmission lubrication. A variable high-pressure port supplies the hydraulic force that it needs to clamp the steel belt tightly between the driving and driven pulley halves. This smart pump arrangement avoids slippage while minimizing power consumption. In addition, the Corolla S\u2019s CVT has a sport mode, paddle shifters, and seven artificial \u201cgears\u201d to address two classic gripes: the rubber-band effect (where the engine revs, and the car\u2019s speed eventually catches up) and the no-driver-involvement issue.<\/p>\n
Ratio spread\u2014the quotient of the lowest drive ratio divided by the highest\u2014is the second area where CVTs are making gains against other transmissions. Compared with the 9.8:1 ratio spread in ZF\u2019s new nine-speed automatic, the Nissan Altima\u2019s 7.0:1 doesn\u2019t sound that impressive, but this was a 17-percent improvement over JATCO\u2019s seventh-generation CVT. Without divulging exactly how far the spread can be stretched, JATCO engineers have admitted that broader ratios are both technically feasible and a top priority in their future designs.<\/p>\n
It is difficult to say at this point whether or not these types of transmissions will subsist in today\u2019s markets; only time will tell.<\/p>\n","protected":false},"excerpt":{"rendered":"
Controlled variable transmissions, or \u201cCTVS,\u201d are gear-free transmissions that are only good because of engine drone under heavy throttle, and they are slowly invading against manuals and conventional automatics, especially in 2014 models. Audi, Honda, Hyundai, Subaru, and Toyota all make their own CVTs. Nissan owns a controlling interest in JATCO, the firm that …<\/p>\n