Continuously Variable Transmissions
A CVT has a nearly infinite range of gear ratios. In the past, CVTs could not compete with four-speed and five-speed transmissions in terms of cost, size and reliability, so you didn't see them in production automobiles. These days, improvements in design have made CVTs more common. The Toyota Prius is a hybrid car that uses a CVT.
The transmission is connected to the engine through the clutch. The input shaft of the transmission therefore turns at the same rpm as the engine.
Photo courtesy DaimlerChrysler
A five-speed transmission applies one of five different gear ratios to the input shaft to produce a different rpm value at the output shaft. Here are some typical gear ratios:
You can read How CVTs Work for even more information on how continuously variable transmissions work. Now let's look at a simple transmission.