New 7-speed Mercedes-Benz transmission

email Andre at: avoglezon@mbzlongbeach.com

• Introduction autumn 2003 in the E-, S-, CL and SL-Classes
  
• New shift principle for faster acceleration
  
• Integrated electronics and state-of-the-art lightweight design
  
• Eleven million Mercedes automatic transmissions built since 1959

Starting in September 2003, Mercedes-Benz will be equipping the E-, S-, CL- and SL-Classes with the new 7G-TRONIC automatic transmission. The 7G-TRONIC offers out-standing performance all round – as well as reducing fuel consumption significantly, it also performs gear changes more quickly and more smoothly than existing automatic transmissions.
 


To meet their ambitious goals, the Mercedes engineers designed the world's first ever volume-production passenger car transmission with seven forward speeds and two manually engaged reverse gears. The result underlines once again that Mercedes-Benz technology leads the way in the passenger car industry.

The new automatic transmission, designed to handle a continuous torque of 700 newton metres, will be standard-fitted in place of the present five-speed automatic transmission in a number of Mercedes-Benz models – initially the E 500, S 430, S 500, CL 500 and SL 500 – starting in autumn 2003.

The new 7G-TRONIC inaugurates the fifth generation of Mercedes-Benz automatic transmissions, thereby continuing a long tradition. Since 1959, Mercedes-Benz has built more than eleven million automatic transmissions – automatic transmissions are standard in the S-Class and are specified in around 88 per cent of E-Class models. In the C-Class, some 65 per cent of all Saloons, Estates and Sports Coupés are fitted with automatic transmission, and the trend is rising.



Reduced fuel consumption and improved driving pleasure

The new seven-speed automatic transmission incorporates a range of technical advances which bring significant improvements on fuel consumption, comfort and driving pleasure:

• Fuel consumption: the new 7G-TRONIC reduces NEDC combined fuel consumption by up to 0.6 litres per 100 kilometres, or around five per cent, depending on model. Under everyday driving conditions, actual fuel savings of well over one litre per 100 km are possible.
  
• Refinement: Gears are engaged between 0.1 and 0.2 seconds sooner, making the torquey V8 engine even more responsive to accelerator inputs. At the same time the transmission also operates more smoothly and more quietly.
  
• Driving pleasure: for the same engine, acceleration times from 0 to 100 km/h are reduced by up to 0.3 seconds compared with the same Mercedes models fitted with the previous five-speed automatic transmission, while as much as 2.1 seconds can be shaved off the 60 to 120 km/h time, which is particularly useful for speedy overtaking.

Fuel consumption and performance figures in detail (models with previous five-speed automatic transmission in brackets):
 
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Optimal ratios for all driving situations




The superior performance of the new automatic transmission is due to a number of different design modifications. Most important among these is the increase in the number of forward speeds, from five to seven. This increases the overall spread, yet at the same time the ratios are closer together than on the five-speed transmission. In this way optimal ratios are provided for virtually all driving situations. On the five-speed transmission the ratio of the highest to the lowest gear was 4.33, whereas the high/low ratio for the new seven-speed automatic transmission is 6.0. This gives the electronic control unit which triggers the gear changes even greater scope for maximising fuel economy and smoothness. One important benefit of this is a significant reduction in average engine speeds. At 100 km/h, for example, engine speeds are reduced by between 800 and 1000 rpm depending on operating conditions. The optimal rev-matching results in more fuel-efficient, quieter operation.

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The shift principle too has been significantly enhanced. When it is necessary to downshift quickly through several gears for speedy acceleration, for example in response to "kickdown", the new seven-speed automatic transmission resorts to a so called "sliding multiple downshift", rather than performing gear changes one after the other. As the name implies, the individual gearshifts partially overlap. For example while the transmission is still changing down from seventh to sixth gear, it will already be initiating the change from sixth to fifth, and before that operation in turn is completed, the transmission will already be starting to change from fifth to fourth. This speeds the overall process of shifting through the gears and at the same time results in greater smoothness, making the individual gear changes virtually imperceptible. The speedier gear changes produce a noticeable increase in agility. Gears are engaged between 0.1 and 0.2 seconds sooner than with the five-speed automatic, resulting in improved acceleration and tractive power.


 

email andre: avoglezon@mbzlongbeach.com