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Mercedes-Benz unveils 7-speed automatic transmission

May, 2003Mercedes-Benz have announced that its world's first standard-fitted seven-speed automatic transmission for passenger cars will be available in Australia from March next year. As standard in the E 500, S 430, S 500, CL 500 and SL 500 models, the new 7G-TRONIC seven-speed automatic transmission will replace the five-speed automatic version currently fitted delivering enhanced shifting comfort, fuel economy (saving up to 0.6 litres per 100 kilometres according to the manufacturers) and a further boost to acceleration. The newly developed seven-speed automatic transmission increases acceleration from 0 to 100 km/h by up to 0.3 seconds and allows significantly quicker intermediate sprints from 60 to 120 km/h. Shifting is also smoother and more comfortable than with the automatic transmission presently used. Mercedes have produced eleven million automatic transmissions since 1959, and in the latest advances engineers have used of seven gear ratios allowwing the automatic transmission to retain the small increases in engine speed which are important in ensuring optimum gear ratios, whilst at the same time offering a larger ratio spread between the lowest and highest gear. This gives the electronic control unit more flexibility to adjust shifting in such as way as to keep fuel consumption low and the transmission's reactions fast. It also lowers the average engine speed - a clear plus point in terms of both cutting fuel consumption and keeping the lid on noise levels. The 7G-TRONIC system facillitates fast gear-change using the principle of repeated downshift - this means that when the driver switches down rapidly through the gears (kickdown), the new transmission does not always select the individual gears in strict order, missing out a particular gear if necessary. In this situation, only two gear changes are actually required - instead of the normal four - in order to accelerate quickly using kickdown. Another feature of the seven-speed automatic transmission is a lockup clutch in the hydrodynamic torque converter designed to eliminate slip between the pump and turbine rotor. It does this by establishing a virtually fixed connection wherever possible between the engine shaft and transmission shaft, creating an extremely effective barrier to output loss. In contrast to conventional automatic transmissions, in which torque converter lockup is only possible in higher gears, the lockup clutch in the new seven-speed automatic transmission from Mercedes-Benz is active from the first gear up. Despite these technical advances, the 7G-TRONIC automatic transmission is barely any larger or heavier than the current five-speed automatic transmission. This is due largely to the use of lightweight magnesium for construction of the transmission casing.Australian recommended retail pricing for models featuring the the transmission will be announced closer to their local release.

About the Author
Mike Hanlon After Editing or Managing over 50 print publications primarily in the role of a Magazine Doctor, Mike embraced the internet full-time in 1995 and became a "start-up all-rounder" – quite a few start-ups later, he founded Gizmag in 2002. Now he can write again.   All articles by Mike Hanlon
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