Mercedes-Benz 7G-Tronic transmission


7G-Tronic is Mercedes-Benz's trademark name for its 7-speed automatic transmission type 722.9. It was produced from 2003 to 2020 in different variants as converter-7-gear-automatic transmission. The core models W7A 400 and W7A 700 are for engines up to or maximum input torque.
This fifth-generation transmission was the first 7-speed automatic transmission ever used on a production passenger vehicle. It initially debuted in Autumn 2003 on 5 different V8-cylinder models: the E 500, S 430, S 500, CL 500, and SL 500. It became available on many 6-cylinder models too. Turbocharged V12 engines, 4-cylinder applications and commercial vehicles continued to use the older Mercedes-Benz 5G-Tronic transmission for many years.
The company claims that the 7G-Tronic is more fuel efficient and has shorter acceleration times and quicker intermediate sprints than the outgoing 5-speed automatic transmission. It has 2 reverse gears.
The transmission can skip gears when downshifting. It also has a torque converter lock-up on all 7 gears, allowing better transmission of torque for improved acceleration. The transmission's casing is made of magnesium alloy, a first for the industry, to save weight. The 7G-Tronic transmission is built at the Mercedes-Benz Stuttgart-Untertuerkheim plant in Germany, the site of Daimler-Benz's original production facility.
In July 2009, Mercedes-Benz announced they are working on a new nine-speed automatic.

Key Data


Specifications

Operating Modes

Regular

In normal condition it sequentially shift gears, but if required it can skip some gears, that are: 7 to 5, 6 to 2, 5 to 3 and 3 to 1. On vehicles with 6 or 8 cylinder engines with comfort mode engaged, as well as on off-road vehicles with low range selected, the transmission will always use 2nd gear as initial gear.

„Limp-Home Mode“

If the transmission control unit senses a critical fault during driving, it will activate an emergency operating mode: Upon hydraulic failures, it will stop shifting gears and permanently retain the currently selected gear; if the failure can be pinpointed to one of the internal hydraulic control valves, the transmission will continue shifting but stop using the affected gear. Upon electrical failure, the transmission shifts to 6th gear. If the critical fault persists after the vehicle is stopped and the engine restarted, only 2nd gear and reverse gear #2 are available.

AMG SpeedShift

AMG SpeedShift TCT

The TCT transmission is essentially the 7G-Tronic automatic transmission including "Torque Converter Technology". Sporty, performance-oriented version with the same gear ratios. First used in 2005 Mercedes-Benz SLK 55 AMG. In 2007, 7G-Tronic transmission with AMG SpeedShift was also called '7G-Tronic Sport'.

AMG SpeedShift MCT

developed the 7-speed MCT "Multi Clutch Technology" planetary automatic transmission. The MCT transmission is essentially the 7G-Tronic automatic transmission without a torque converter. Instead of a torque converter, it uses a compact wet startup clutch to launch the car from a stop and also supports computer-controlled double-clutching. The MCT acronym refers to a planetary transmission's multiple clutches and bands for each gear.
The MCT is fitted with 4 drive modes: "C", "S", "S+" and "M" and boasts 0.1 second shifts in "M" and "S+" modes. MCT-equipped cars are also fitted with the new AMG Drive Unit with an innovative Race Start function. The AMG Drive Unit is the central control unit for the AMG SpeedShift MCT 7-speed sports transmission and all driving dynamics functions. The driver can change gears either using the selector lever or by nudging the steering-wheel shift paddles. The new Race start Function is a launch control system that enables the driver to call on maximum acceleration while ensuring optimum traction of the driven wheels.
It is available on the 2009 SL 63 AMG and E 63 AMG, and will be used for the 2011 S 63 AMG and CL 63 AMG, and the 2012 CLS 63 AMG and C 63 AMG. Compulsory on the 2014 CLS 63 and E 63 AMG models, as well as their "S--Model" variants. Improved with the release of the 2015 model year, by decreasing the lag time between shifts.

Combined Parallel and Serial Coupled Gearset Concept For More Gears And Improved Cost-Effectiveness

This is Mercedes-Benz second generation of advanced automatic transmissions. The design is more advanced than its direct predecessor, but significantly less economical than its competitors. Since Mercedes can charge higher prices than many of its competitors, it was possible to include the 7G-Tronic in the range. With its all new parallel power flow the W7A is referred to at Mercedes-Benz as '''NAG 2.

Gearset Concept: Quality

The W7A uses no bands nor sprag clutches. It is fully electronic controlled. Torque converter lock-up can operate in all 7 forward gears.
As shown in the assessment table below, the biggest weakness of the gearset concept is the two consecutive reductions in speed increase in 6th and 7th gear.

Applications

Mercedes models

Mercedes C-Class

[Infiniti]