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  • Ford PowerShift transmission

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    The Ford PowerShift is a six-speed dual clutch semi-automatic transmission produced by the Ford Motor Company. The Ford PowerShift gearboxes are built by Getrag Ford Transmissions, a joint-venture with Getrag. PowerShift improves fuel efficiency by as much as 10 percent when compared to a conventional automatic transmission. The operation of a dual clutch transmission is analogous to two traditional manual transmissions, each with its own clutch, operating in parallel and alternating shifts. The Ford unit is a six-speed with one clutch acting on first, third and fifth gear, and the other used for second, fourth and sixth gear. As first gear is engaged, the 2-4-6 clutch is disengaged and the second gear cogs are engaged. At the appropriate time, the 1-3-5 clutch is disengaged and the 2-4-6 clutch is engaged. While in second gear, the other side shifts from first to third. The process is repeated with none of the efficiency loss normally associated with torque converters and, in theory, quick smooth shifts. The PowerShift gearbox is a joint development between Ford, Getrag and Luk and was first introduced in Europe. Both Volvo and Ford use wet clutches and hydraulic actuation. However, the new PowerShift gearbox used in the Ford Fiesta and Ford Focus uses dry clutches and electric motor/solenoid actuation. Some have criticized the PowerShift's rough starts and lack of smooth shifting, but Ford has continually released (but not publicized) upgrades, also known as under the table fixes, to transmission software and firmware designed to address these failures. These improvements have not resulted in a lasting or permanent remedy for the ongoing, widespread problems associated with the transmission.

  • Continuously variable transmission

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    A continuously variable transmission (CVT), also known as a shiftless transmission, single-speed transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a 'twist-and-go', is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT with suitable control may allow the input shaft to maintain a constant angular velocity even as the output speed varies. A belt-driven design offers approximately 88% efficiency, which, while lower than that of a manual transmission, can be offset by lower production cost and by enabling the engine to run at its most efficient speed for a range of output speeds. When power is more important than economy, the ratio of the CVT can be changed to allow the engine to turn at the RPM at which it produces greatest power. This is typically higher than the RPM that achieves peak efficiency. In low-mass low-torque applications (such as motor scooters) a belt-driven CVT also offers ease of use and mechanical simplicity.

  • List of automobiles with continuously variable transmissions

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    The following is a list of automobiles that use continuously variable transmission (CVT) technology to transmit power from their engines to their wheels.

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