FIESTA POWERSHIFT AUTOMATIC DELIVERS RESPONSIVE PERFORMANCE WITH CLASS-LEADING FUEL ECONOMY
- Ford Fiesta delivers class-leading fuel efficiency with an advanced PowerShift six-speed automatic transmission based on manual transmission technology
- PowerShift characteristics are particularly well-suited to smaller car applications, making
the transmission a perfect fit for Fiesta and the upcoming Ford Focus
- Design complexity and internal friction reduced through the use of dual internal dry clutches, while six forward gears help deliver exceptional fuel economy and performance without compromise to engaging driving dynamics
- Optimal shift spacing, small gear ratio steps and clever electronic controls help the PowerShift keep Fiesta’s 1.6-liter I-4 engine in peak efficiency range
SAN FRANCISCO, April 19, 2010 – The 2011 Ford Fiesta offers an advanced PowerShift automatic transmission that combines the convenience of a traditional automatic with the responsive performance of a manual gearbox. The result of this combination is Fiesta’s class-leading fuel economy of up to 40 mpg on the highway.
“The dual-clutch automatic is a game-changing transmission for Ford,” said Piero Aversa, team leader for PowerShift development. “We believe this new automatic transmission for the Fiesta will be the most advanced in the segment, offering increased responsiveness and performance – all while helping keep the engine in its peak efficiency mode – resulting in class-leading fuel economy.”
Dual internal clutches, no clutch pedal
PowerShift is an advanced automatic transmission based on the proven efficiency of manual transmission technology.
Traditional automatic transmissions have internal clutches – invisible to the driver – to enable gear changes. Working in combination with a torque converter spinning in a pool of automatic transmission fluid, a traditional automatic relies on hydraulic pressure generated by a power-sapping pump to deliver power to the wheels.
PowerShift maintains a pair of internal clutches, but eliminates everything else.
A manual transmission has long been a fuel-efficient choice for drivers aiming to squeeze every last mile from each gallon of gasoline. A single, manually controlled clutch allows changes among a single set of gears. While manual shift technology increased mechanical efficiency, economical driving required that a motorist possess the manual dexterity to coordinate engine speed, gear selection and clutch engagement, all while steering, stopping and accelerating.
PowerShift employs twin internal clutches to keep changes among its six forward gears smooth and seamless, automatically. One clutch supports the uneven gearset, one, three and five; while the other clutch controls the even gears, two, four and six. The powertrain control unit that electronically integrates and harmonizes engine and PowerShift automatic transmission operation keeps the engine in peak efficiency range at all times. In conjunction with six optimally spaced gears, PowerShift increases smoothness between gears, without engine torque falling off.
Fiesta’s PowerShift automatic with six speeds is unique among small cars, as competitive offerings feature only four- and five-speed automatic transmissions.
Dry means simple and efficient
PowerShift transmits power and torque through dual internal clutches with dry friction material facings – much like the clutch in a manual transmission – eliminating the need for a torque converter, planetary gearsets, weighty pumps, hydraulic fluids and the coolers and lines required in a traditional automatic. In addition to inherently increased mechanical efficiency, PowerShift saves more than 30 pounds compared to four-speed automatics in similar small cars.
“A dry clutch is a real sweet spot for small car applications,” said Aversa. “PowerShift dry clutch facings save weight, improve efficiency, increase smoothness and add durability, and the entire unit is sealed with low-friction gear lubricant for the 150,000-mile projected life of the vehicle. This transmission requires no regular maintenance.”
“A critical objective for the PowerShift development team was intuitive operation by any potential driver,” said Aversa. “As PowerShift is based on manual transmission technology, we’ve incorporated features that replicate the feeling of a traditional automatic. These include micro-slip, creep function and neutral idle.”
Micro-slip is tiny clutch slippage – precisely controlled – to enable smooth gear changes and significantly reduce powertrain noise, vibration and harshness (NVH). This minimal slippage also enables the engine to run at lower rpm levels in fifth and sixth gear, aiding fuel efficiency.
To aid familiarity of PowerShift to drivers accustomed to conventional automatic transmissions, a creep-forward function has been added to mimic the gentle progress made – independent of the accelerator pedal – when a traditional automatic is in drive or reverse. This motion allows vehicle speed to be controlled by the brake pedal, as in low-speed parking maneuvers or backing out of a driveway.
Neutral idle allows the clutches to disengage under deceleration. With disengaged clutches, the transmission “freewheels” without interference or friction to aid fuel economy. This ability to coast replicates the feeling of a conventional automatic transmission when decelerating in drive, but without the inherent friction or drag.
Rolling backward when stopped on a hill has always tested the skills of even well-seasoned manual transmission drivers. Balancing throttle input, clutch engagement and brake release for a smooth launch has traditionally required skill, timing and nerve. As PowerShift is based on manual transmission technology, rollback prevention mandated innovation.
A competitive dual-clutch automatic on the market can exhibit rollback on a steep driveway, requiring the driver to “tickle” the accelerator pedal for modulation.
Fiesta with PowerShift, on the other hand, is equipped with Hill Start Assist.
By coupling the PowerShift transmission with braking technology, a Fiesta driver will experience no rollback when stopped on a hill – again replicating the predictable behavior of a traditional automatic.
When the digital accelerometer sensor determines an incline, Hill Start Assist holds braking pressure as the driver transitions from the brake pedal to the accelerator. Precisely balanced, the Fiesta exhibits neither holdback nor drive-off against the brake.
This allows the driver to smoothly and seamlessly launch the Fiesta on an incline regardless of degree.
“PowerShift is the best of both worlds,” said Aversa. “It offers convenience, comfort and accessibility to a broader range of drivers like a conventional automatic, while delivering the mechanical efficiency – both fuel economy and responsive performance – of a manual transmission. Six forward gears enables PowerShift to optimize for fuel efficiency or performance based on driver input. It’s innovation by internal simplification, coupled with smart controls.”
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About Ford Motor Company
Ford Motor Company, a global automotive industry leader based in Dearborn, Mich., manufactures or distributes automobiles across six continents. With about 198,000 employees and about 90 plants worldwide, the company's automotive brands include Ford, Lincoln, Mercury and, until its sale, Volvo. The company provides financial services through Ford Motor Credit Company. For more information regarding Ford's products, please visit www.ford.com .
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