What Is a CVT Transmission in a 2006 Ford 500?by Jeb Hoge
The Ford 500 sold from 2005 to 2007 and came with options for two different transmissions. One was a six-speed automatic transmission installed in the SEL and Limited front-drive models, but the other was a continuously variable transmission, or CVT, used in the SE front-drive model and in all of the all-wheel drive Ford 500s, as well as in all of the Ford Freestyle crossovers. This was an unusual choice of transmission for Ford's big flagship sedans for a number of reasons.
A CVT uses a system of pulleys and belts or chains instead of gears to conduct power from the engine to the wheels. The system was designed to allow linear changes in the input-to-output ratio for power transfer, as opposed to a conventional automatic, which offers only a certain number of ratio "steps" from gear to gear. The CVT can leap from a low ratio directly to a high ratio, or can slowly change the ratio as needed, based on the driver's input.
Benefits of a CVT
Because of the linear nature of the CVT's operation, it's an unusually smooth and flexible transmission. There is no sensation of shifting or of the engine peaking and dropping, as you would expect with a conventional transmission. The CVT also works with the engine control system, including the electronic throttle, to find the best compromise of torque, fuel efficiency and emissions. The CVT never "hunts" between gears to find the best ratio; it just adjusts to it.
Downsides to the CVT
Drivers used to conventional automatics often disliked the CVT. For example, since there are no shift points, the engine revs to a certain rpm and then stays there while the transmission varies the pulley ratio to produce acceleration. The sensation is similar to a conventional automatic failing to shift properly. The Ford 500's Duratec engine could be noisy when accelerating, since it maintained revs rather than rising and falling through the rev band.
Driving the CVT-equipped Ford 500 qualifies for a one-word definition: smooth. From a standstill, the Ford 500 gets underway with an elastic feeling since there is no one-two shift. Full-throttle starts have a moment of hesitation as the engine revs to 4,500 rpm before the car starts rolling, holding those revs until the desired speed is reached. While cruising, the transmission allows the engine to drop to low revs whenever it can, increasing fuel efficiency, but it often adjusts minimally to account for hills or other variations that might require slightly more power.
Jeb Hoge has a degree in English and more than 10 years of experience as a technical/business writer supporting federal defense contractors and government agencies. He is a member of the Society of Technical Communicators and Toastmasters.