7G-Tronic is Mercedes-Benz's trademark name for its seven-speed automatic transmission, starting off with the W7A 700 and W7A 400 as core models.
Abstract
This fifth-generation transmission was the first seven-speed automatic transmission ever used on a production passenger vehicle. In all applications this transmission is identified as the New Automatic GearboxGeneration Two, or NAG2. It initially debuted in Autumn 2003 on five different eight-cylinder models: the E500, S 430, S 500, CL 500, and SL 500. It also soon became available on many six-cylinder models. Turbocharged V12 engines, four 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 two reverse gear ratios.. The transmission can skip gears when downshifting. It also has a torque converter lock-up on all seven 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. About 65 percent of Mercedes-Benz C-Class sedans, wagons, and sport coupes are purchased with automatic transmissions. However, about 88 percent of Mercedes-Benz E-Class sedans and wagons are purchased with automatic transmissions, and automatic transmissions are standard on the Mercedes-Benz S-Class. The transmission is currently available on the SsangYong's vehicles like Rexton, and Korando Turismo /Turismo. In July 2009, Mercedes-Benz announced they are working on a new nine-speed automatic.
Specifications
Basic concept
Progress is reflected in 7 forward gears out of 11 main components, compared to 5 forward gears out of 9 main components. This turns out the design as advanced compared to its predecessor but less economical compared to its competitors. It uses no bands nor sprag clutches. It is fully electronic controlled. Torque converter lock-up can operate in all 7 forward gears.
Gear ratios
Gears functionality
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. For 6 or 8 cylinder gasoline engines and if sport mode is not selected, transmission will start in 2nd gear. Also, if it is an offroad vehicle, if low range is selected, it will start in 2nd gear too. If emergency mode is activated, like when an electric fault or another critical fault occurs, the 6th gear is selected by default.
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 four drive modes: “C”, “S”, “S+” and “M” and boasts 100 millisecond 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 E63 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 AMG CLS63 and E63 models, as well as their "S--Model" variants. Improved with the release of the 2015 model year, by decreasing the lag time between shifts.
