9G-TRONIC, Mercedes and its most efficient automatic gearbox

In 2003 Mercedes introduced the 7G-TRONIC automatic gearbox, which in 2011 evolved into the 7G-TRONIC PLUS. This seven-speed gearbox has its days numbered with the latest Mercedes automatic gearbox, the 9G-TRONIC. It is an automatic gearbox with a torque converter and epicyclic trains, which offers nine relationships and which will gradually be implemented in most of the star models. This box is suitable for both rear-wheel drive and 4×4 models, as well as hybrid powertrains. hold on 1000Nm torque without problems.

The new box is more efficient for various reasons, the first is obvious, the greater number of relations allows a better staggering of speeds and longer relations in the last gears, which allow traveling almost with the engine at idle. Their lubrication is up to 54% more efficient thanks to the use of two oil pumps.

The new gearbox is more efficient because it is also lighter and more compact, and other measures such as the adoption of the two oil pumps. One of them is mechanical and will be responsible for providing proper lubrication when the engine is running. The other pump is electric and will only work if the electronic control unit deems it appropriate, which will be when we subject the box to more work and effort (constant changes at high speed, towing loads...). The electric pump will also be able to provide movement to the box in hybrid models, without the need for the engine to run at stable speeds.

The 9G-TRONIC transmission offers three driving modes. The first is the Eco mode and it prioritizes the insertion of long gears to reduce consumption, it also does it in a smoother, slower way. In Sport and Manual modes, the gear change becomes more abrupt and faster and allows the engine to rev more. Circulating in automatic mode we can activate the change by means of the cams, passing it to manual. After a while of inactivity, the change will return to automatic mode. The modes are selected from a selector. The gear lever only offers P, R, N and D positions.

Premiere on the Mercedes E-Class

The first Mercedes to use this new nine-speed automatic gearbox is the E-Class 350 BlueTEC, launched in the summer of 2013. With a 6-liter V3.0 diesel and 252CV, it produces a surprising average consumption of 5,3 liters in the sedan body, 0,2 tenths more in the family model. CO2 emissions are 138 grams per kilometer. It also has good performance, with a 0-100 in 6,6 seconds and a top speed of 250 km/h.

The advantages for this Class E are clear. Better staggered gears and lower consumption thanks to the nine ratios, which allow long developments so that the engine travels relaxed. In the case of the E 350 BlueTEC, driving at 120km/h the engine rotates at 1.350 revolutions. Lower revolutions also means less noise, four decibels to be exact.

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Source – Mercedes