Mercedes-Benz 7G-Tronic transmission

7G-Tronic
Overview
Manufacturer	Daimler AG
Production	2003–2020
Body and chassis
Class	7-speed longitudinal automatic transmission
Chronology
Predecessor	Mercedes-Benz 5G-Tronic transmission
Successor	Mercedes-Benz 9G-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.

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 Gearbox Generation 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.

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.

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 in the previous 5G-Tronic transmission. 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

Gear Teeth and Ratios				Planetary Gear Set: Teeth				Count	Total	Avg.
				Ravigneaux		Simple
Model Type	Version First Delivery			${S_{1}}$ ${R_{1}}$	${S_{2}}$ ${R_{2}}$	${S_{3}}$ ${R_{3}}$	${S_{4}}$ ${R_{4}}$	Brakes Clutches	Ratio Span	Gear Step
Gear $n$	R 1	R 2	R 3	1	2	3	4	5	6	7
Step $i_{n-1}/i_{n}$	–R1 : 1	–R2 : 2	–R3 : 3		1 : 2	2 : 3	3 : 4	4 : 5	5 : 6	6 : 7
W7A ALL 722.9	700 N⋅m (516 lb⋅ft) 2003			42 86	86 110	28 76	46 114	4 3	6.0162	1.3486
Ratio $i_{n}$	−3.4157 $-{\tfrac {8,372}{2,451}}$	−2.2307 ${\tfrac {38,272}{17,157}}$	−1.4987 ${\tfrac {598}{399}}$	4.3772 ${\tfrac {203,840}{46,569}}$	2.8586 ${\tfrac {133,120}{46,569}}$	1.9206 ${\tfrac {2,080}{1,083}}$	1.3684 ${\tfrac {26}{19}}$	1.0000 ${\tfrac {1}{1}}$	0.8204 ${\tfrac {38,272}{46,651}}$	0.7276 ${\tfrac {8,372}{11,507}}$
Step	0.7804	0.7804	0.7804		1.5313	1.4884	1.4035	1.3684	1.2189	1.1276
Ratio R & even	$-{\tfrac {S_{4}(S_{1}+R_{1})(S_{3}+R_{3})}{R_{1}S_{3}R_{4}}}$		$-{\tfrac {S_{4}(S_{3}+R_{3})}{S_{3}R_{4}}}$		${\tfrac {(S_{1}+R_{1})(S_{3}+R_{3})(S_{4}+R_{4})}{R_{1}R_{3}R_{4}}}$		${\tfrac {S_{3}+R_{3}}{R_{3}}}$		${\tfrac {S_{4}(S_{1}+R_{1})(S_{3}+R_{3})}{S_{4}(S_{1}+R_{1})(S_{3}+R_{3})+S_{1}S_{3}R_{4}}}$
Ratio R1 & odd	$-{\tfrac {S_{4}(S_{2}+R_{2})(S_{3}+R_{3})}{S_{2}S_{3}R_{4}}}$			${\tfrac {(S_{2}+R_{2})(S_{3}+R_{3})(S_{4}+R_{4})}{S_{2}R_{3}R_{4}}}$		${\tfrac {(S_{3}+R_{3})(S_{4}+R_{4})}{R_{3}R_{4}}}$		${\tfrac {1}{1}}$	${\tfrac {S_{4}(S_{2}+R_{2})(S_{3}+R_{3})}{S_{4}(S_{2}+R_{2})(S_{3}+R_{3})+R_{2}S_{3}R_{4}}}$

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.

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(s). 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

Mercedes-AMG 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 (Multi-Clutch Technology) acronym refers to a planetary (automatic) transmission's multiple clutches and bands for each gear.

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 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 AMG CLS 63 and E 63 models, as well as their "S--Model" variants. Improved with the release of the 2015 model year, by decreasing the lag time between shifts.

Applications

Mercedes models

Mercedes C-Class

• 2005-2007 Mercedes-Benz W203 (C 320 CDI, C 230, C 280, C 350; post-facelift)
• 2005-2007 Mercedes-Benz CL203 (C 230 SportCoupé, C 350 SportCoupé; post-facelift), (CLC 250, CLC 350)
• 2011–2018 Mercedes-Benz W204 (C 63 AMG, C 63 AMG Black Series)
• 2014 Mercedes-Benz W205 (C 180)

Mercedes E-Class

• 2009–2016 Mercedes-Benz W212 (E200AMG 7G-Tronic,E63AMG)
• 2009–2013 Mercedes-Benz W212 (E200AMG 7G-Tronic)
• 2005–2009 Mercedes-Benz W211 (E350 v6 7G-Tronic)

Mercedes S-Class

• 2013–2017 Mercedes-Benz W222 (all models except Maybach S 500 and Maybach S 500 4MATIC)
• 2017–2020 Mercedes-Benz W222 (V12 models only)

Mercedes SLK-Class

• 2004–2011 Mercedes-Benz R171
• 2011–2015 Mercedes-Benz R172

Mercedes CLS-Class

• 2003-2010 Mercedes-Benz C219
• 2010-2018 Mercedes-Benz C218

Mercedes CLK-Class

• 2002–2010 Mercedes-Benz C209

Non Mercedes-Benz models

Infiniti

• 2014–2019 Infiniti Q50 (2.0t (M274 DE20 LA)).
• 2015–2016 Infiniti Q50 (2.2d (OM651 22 LA)).
• 2017–2018 Infiniti Q60 (2.0t (M274 DE20 LA) ).

SsangYong Motor

• 2017–2020 SsangYong Rexton G4 (2.2 e-XDi Euro 6 Turbo-Diesel )

See also

• List of Daimler AG transmissions

External links

• 7g-Tronic ECU Repair
• GermanCarFans
• "7G-Tronic: Mercedes-Benz presents the world's first seven-speed automatic transmission for passenger cars" (PDF). DaimlerChrysler press release. Archived from the original (PDF) on 6 July 2011. Retrieved 14 October 2008.
• ATT24 GmbH