Mercedes-Benz 7G-Tronic transmission

7G-Tronic is Mercedes-Benz's trademark name for its seven-speed automatic transmission, starting off with the W7A 700 and W7A 400 (Wandler-7-Gang-Automatik bis 700 oder 400 Nm Eingangsdrehmoment; converter-7-gear-automatic with 516 or 295 ft·lb maximum input torque; type 722.9) as core models.

7G-Tronic
Overview
ManufacturerDaimler AG
Production2003–
Body and chassis
Class7-speed longitudinal automatic transmission
Chronology
PredecessorMercedes-Benz 5G-Tronic transmission
SuccessorMercedes-Benz 9G-Tronic transmission

AbstractEdit

This fifth-generation transmission was the first seven-speed automatic transmission ever used on a production passenger vehicle.[1] 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.[1] It has two reverse gear ratios. .

The transmission can skip gears when downshifting. It also has a lockup torque converter 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.[citation needed] 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 (with that figure rising). 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 (in South Korea)/Turismo (in UK). In July 2009, Mercedes-Benz announced they are working on a new nine-speed automatic.[2]

SpecificationsEdit

Main designEdit

7 forward gears plus 2 reverse out of 11 main components: 2 simple planetary gear sets, 1 Ravigneaux (considered as 2), 4 brakes and 3 clutches[3][4][5]. It uses no bands nor sprag clutches[4]. Turn out the design as advanced compared to its predecessor but less economical compared to its competitors.

Gears functionalityEdit

In normal condition it sequentially shift gears, but if required can skip some gears, that are: 7 to 5, 6 to 2, 5 to 3 and 3 to 1.[4]

For 6 or 8 cylinder gasoline engines and if Sport mode is not selected, transmission will start in 2nd gear. Also, if it is a Off road vehicle, if Low range is selected, will start in 2nd gear too.[6]

If emergency mode is activated, like when occurs an electric fault or another critical fault, 6th gear default is selected (all solenoids off).[4]

ControlEdit

It is a fully electronic controlled unit. Torque converter lock up can operate in all 7 forward gears.[4]

Gear ratiosEdit

Gear Teeth and Ratios Planetary Gear Set: Teeth Count Total Avg.
Ravigneaux Simple
Model

Type

First Delivery Sun 1.1

Ring 1.1

Sun 1.2

Ring 1.2

Sun 2

Ring 2

Sun 3

Ring 3

Brakes

Clutches

Ratio

Span

Gear

Step

Gear 1 2 3 4 5 6 7 R 1 R 2
W7A ALL

722.9

2003[3][5] 42

86

86

110

28

76

46

114

4

3

6.0162 1.3486
Ratio 4.3772 2.8586 1.9206 1.3684 1.0000 0.8204 0.7276 - 3.4157 - 2.2307

AMG SpeedShiftEdit

AMG SpeedShift TCTEdit

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.[7]

In 2007, 7G-Tronic transmission with AMG SPEEDSHIFT was also called '7G-Tronic Sport'.[8]

AMG SpeedShift MCTEdit

Mercedes-AMG developed the 7-speed MCT "Multi Clutch Technology" planetary semi-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 declutching. The MCT (Multi-Clutch Technology) acronym refers to a planetary (automatic) transmission’s multiple clutches and bands for each gear.[9]

The MCT is fitted with four drive modes: “C” (Comfort), “S” (Sport), “S+” (Sport plus) and “M” (Manual) and boasts 100 millisecond shifts in "M" and "S+" modes. MCT-equipped cars are also fitted with the new AMG DRIVE UNIT with 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 which 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 lag time between shifts.

See alsoEdit

ReferencesEdit

  1. ^ a b "7G-Tronic: Mercedes-Benz presents the world's first seven-speed automatic transmission for passenger cars" (PDF). DaimlerChrysler press release.
  2. ^ 19 July 2010. "Merc plans nine-speed auto'". Autocar.co.uk. Retrieved 2010-07-20.
  3. ^ a b "Catalog" (PDF). shop.ukrtrans.biz. Retrieved 2020-01-15.
  4. ^ a b c d e "Mercedes Benz 722.9 Training Manual" (PDF).
  5. ^ a b [1][dead link]
  6. ^ "Mercedes Benz 722.9 Workshop Tips and Tricks Manual" (PDF).
  7. ^ [2][dead link]
  8. ^ [3][dead link]
  9. ^ [4][dead link]

External linksEdit