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Mercedes-Benz 7G-Tronic transmission

Motor vehicle automatic transmission model

Field	Value
name	7G-Tronic
model_code	W7A 400 · W7A 700 · Type 722.9
production	2003–2020
manufacturer	Daimler AG
class	7-speed longitudinal automatic transmission
related	ZF 6HP · ZF 8HP
predecessor	5G-Tronic
successor	9G-Tronic
image	Mercedes-Benz 7G-Tronic transmission.jpg
caption	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 400 Nm or 700 Nm 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

Model	Type	First
Deliv-
ery	Gear	Total Span	Avg.
Step	Components	Nomenclature	R 2	R 1	1	2	3	4	5	6	7	Nomi-
nal	Effec-
tive	Cen-
ter	Total	per
Gear	Cou-
pling	Gears
Count	Ver-
sion	Maximum Input Torque	W7A 400
W7A 700
W7A 900
722.9
NAG 2
2003													4 Gearsets
4 Brakes
3 Clutches		W	7	A	400 Nm
700 Nm
1000 Nm

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(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 4 drive modes: "C" (Comfort), "S" (Sport), "S+" (Sport plus) and "M" (Manual) 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 (New Automatic Gearbox Generation, starting with type 722.6 as generation 1 and continuing with type 722.9 as generation 2).

With
Assessment	Output:
Gear
Ratios	Innovation
Elasticity{{efn	name="Progress"	Innovation Elasticity Classifies Progress And Market Position	Input: Main Components	Total	Gearsets	Brakes	Clutches	W7A
Ref. Object	n_{O1}
n_{O2}	Topic	n_I= n_G+
n_B+ n_C	n_{G1}
n_{G2}	n_{B1}
n_{B2}	n_{C1}
n_{C2}	Δ Number	n_{O1}- n_{O2}	n_{I1}- n_{I2}	n_{G1}- n_{G2}	n_{B1}- n_{B2}	n_{C1}- n_{C2}	Relative Δ	Δ Output
\tfrac{n_{O1}- n_{O2}} {n_{O2}}	\tfrac{n_{O1}- n_{O2}} {n_{O2}}: \tfrac{n_{I1}- n_{I2}} {n_{I2}}
=\tfrac{n_{O1}- n_{O2}} {n_{O2}} \cdot \tfrac{n_{I2}} {n_{I1}- n_{I2}}	Δ Input
\tfrac{n_{I1}- n_{I2}} {n_{I2}}	\tfrac{n_{G1}- n_{G2}} {n_{G2}}	\tfrac{n_{B1}- n_{B2}} {n_{B2}}	\tfrac{n_{C1}- n_{C2}} {n_{C2}}	W7A
W5A{{efn	Direct Predecessor	Progress	Δ Number	Relative Δ	W7A
ZF 8HP{{efn	Reference Standard (Benchmark)	Late
Market Position	Δ Number	Relative Δ	W7A
ZF 6HP{{efn	Reference Standard (Benchmark) at that time	Early
Market Position	Δ Number	Relative Δ	W7A
3-Speed{{efn	Historical Reference Standard (Benchmark)	Historical
Market Position	Δ Number	Relative Δ
7
5	title=7G-Tronic Automatic Transmission Catalog (722.9)	url=http://shop.ukrtrans.biz/wp-content/uploads/catalogs/722.9.pdf	url-status=dead	archive-url=https://web.archive.org/web/20221013012728/http://shop.ukrtrans.biz/wp-content/uploads/catalogs/722.9.pdf	archive-date=2022-10-13	website=atra.com	publisher=Automatic Transmission Rebuilders Association	language=en}}
9	4
3	4
3	3
3
2	2	1	1	0

\tfrac{2} {5}
\tfrac{2} {5} : \tfrac{2} {9}= \tfrac{2} {5} \cdot \tfrac{9} {2}= \tfrac{9} {5}
\tfrac{2} {9}
\tfrac{1} {3}
\tfrac{1} {3}
\tfrac{0} {3}
7
8	11
9	4
4	4
3	3
2
-1	-2	0	-1	-1

\tfrac{-1} {8}	}
\tfrac{2} {9}
\tfrac{0} {4}
\tfrac{1} {3}
\tfrac{1} {2}
7
6	11
8	4
3	4
2	3
3
1	3	1	2	0

\tfrac{1} {6}	}
\tfrac{3} {8}
\tfrac{1} {3}
\tfrac{2} {2}
\tfrac{0} {3}
7
3	11
7	4
2	4
3	3
2
4	4	2	1	1

\tfrac{4} {3}	****
\tfrac{4} {3}: \tfrac{4} {7}= \tfrac{4} {3} \cdot \tfrac{7} {4}= \tfrac{7} {3}
\tfrac{4} {7}
\tfrac{2} {2}
\tfrac{1} {3}
\tfrac{1} {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.

In-Depth Analysis{{efn	name="Gear Ratio"	**Gear Ratio (Transmission Ratio) i_n
— Speed Conversion —**	Planetary Gear Set: Teeth{{efn	Layout	Count	Nomi-
nal{{efn	Total Ratio Span (Total Gear Ratio/Total Transmission Ratio) Nominal	Cen-ter{{efn	Ratio Span's Center	Ravigneaux	Simple	Avg.{{efn	Average Gear Step	Model
Type	Version
First Delivery	S1
R1	S2
R2	S3
R3	S4
R4	Brakes
Clutches	Gear
Ratio
Span	Gear
Step{{efn	name="50:50"	**Standard 50:50
— 50 % Is Above And 50 % Is Below The Average Gear Step —**	Gear	R 2	R 1	1	2	3	4	5	6	7	Gear
Ratio	\color{grey} {i_{R3}}	{i_{R2}}	{i_R}	{i_1}	{i_2}	{i_3}	{i_4}	{i_5}	{i_6}	{i_7}	Step	\color{grey} \frac{i_{R2}} {i_{R3}}	\frac{i_{R1}} {i_{R2}}	-\frac{i_{R1}} {i_1}{{efn	name="R:1"	**Standard R:1
— Reverse And 1st Gear Have The Same Ratio —**	\frac{i_1} {i_1}	\frac{i_1} {i_2}{{efn	name="1:2"	**Standard 1:2
— Gear Step 1st To 2nd Gear As Small As Possible —**	\frac{i_2} {i_3}	\frac{i_3} {i_4}	\frac{i_4} {i_5}	\frac{i_5} {i_6}	\frac{i_6} {i_7}	Δ Step{{efn	name="Step"	**Standard STEP
— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —**	\color{grey}\tfrac{i_{R1}} {i_{R2}} : \tfrac{i_{R2}} {i_{R3}}	\tfrac{i_1} {i_2} : \tfrac{i_2} {i_3}	\tfrac{i_2} {i_3} : \tfrac{i_3} {i_4}	\tfrac{i_3} {i_4} : \tfrac{i_4} {i_5}	\tfrac{i_4} {i_5} : \tfrac{i_5} {i_6}	\tfrac{i_5} {i_6} : \tfrac{i_6} {i_7}	Shaft
Speed	\color{grey}\frac{i_1}{i_{R3}}	\frac{i_1} {i_{R2}}	\frac{i_1} {i_{R1}}	\frac{i_1} {i_1}	\frac{i_1} {i_2}	\frac{i_1} {i_3}	\frac{i_1} {i_4}	\frac{i_1} {i_5}	\frac{i_1} {i_6}	\frac{i_1} {i_7}	Δ Shaft
Speed{{efn	name="Speed"	**Standard SPEED
— From Small To Large Gears: Steady Increase In Shaft Speed Difference —**	\color{grey}\tfrac{i_1} {i_{R2}} - \tfrac{i_1}{i_{R3}}	\tfrac{i_1} {i_{R1}} - \tfrac{i_1} {i_{R2}}	0 - \tfrac{i_1} {i_{R1}}	\tfrac{i_1} {i_1} - 0	\tfrac{i_1} {i_2} - \tfrac{i_1} {i_1}	\tfrac{i_1} {i_3} - \tfrac{i_1} {i_2}	\tfrac{i_1} {i_4} - \tfrac{i_1} {i_3}	\tfrac{i_1} {i_5} - \tfrac{i_1} {i_4}	\tfrac{i_1} {i_6} - \tfrac{i_1} {i_5}	\tfrac{i_1} {i_7} - \tfrac{i_1} {i_6}	Torque
Ratio	\color{grey}\mu_{R3}	\mu_{R2}	\mu_{R1}	\mu_1	\mu_2	\mu_3	\mu_4	\mu_5	\mu_6	\mu_7	Efficiency
\eta_n	\color{grey}\frac{\mu_{R2}} {i_{R2}}	\frac{\mu_{R2}} {i_{R2}}	\frac{\mu_{R1}} {i_{R1}}	\frac{\mu_1} {i_1}	\frac{\mu_2} {i_2}	\frac{\mu_3} {i_3}	\frac{\mu_4} {i_4}	\frac{\mu_5} {i_5}	\frac{\mu_6} {i_6}	\frac{\mu_7} {i_7}	W7A 400
W7A 700
W7A 900
722.9	Gear	R 2	R 1	1	2	3	4	5	6	7	Gear
Ratio	Step	1.0000	Δ Step	Speed	1.0000	Δ Speed	1.0000	Torque
Ratio	Efficiency
\eta_n	Actuated Shift Elements{{efn	Permanently coupled elements	Brake 1	Brake 2	Brake 3	Brake BR	Clutch 1	Clutch 2	Clutch 3	Geometric Ratios: Speed Conversion	Gear
Ratio
R2 & 5
Ordinary{{efn	name="ordinary"	Ordinary Noted	Gear
Ratio
R1 & 1
Ordinary
Elementary
Noted	Gear
Ratio
2–4
Ordinary
Elementary
Noted	Gear
Ratio
6 & 7
Ordinary
Elementary
Noted	Kinetic Ratios: Torque Conversion	Torque
Ratio
R2 & 5	Torque
Ratio
R1 & 1	! Torque
Ratio
2–4	! Torque
Ratio
6 & 7
400 Nm
700 Nm
1000 Nm
NAG 2 · 2003	42
86	86
110	28
76	46
114	4
3

\color{grey}\tfrac{598} {399}
\tfrac{38,272} {17,157}	}
\tfrac{203,840} {46,569}
\tfrac{133,120} {46,569}
\tfrac{2,080} {1,083}	}	}	}	}
	1.5313			1.4884			1.2189	1.1276
					1.0605		1.1226	1.0810
	–1.9622		1.5313	2.2791	3.1987	4.3772
	0.6808		0.5313	0.7478	0.9196	1.1785
	–2.1400
–2.0955	–3.2433
–3.1594	4.2560
4.1965	2.8083
2.7833	1.8993
1.8886	1.3611
1.3574	1.0000	0.8131
0.8094	0.7179
0.7130
	0.9593
0.9394	0.9495
0.9250	0.9723
0.9587	0.9824
0.9737	0.9889
0.9834	0.9946
0.9919	1.0000	0.9912
0.9866	0.9868
0.9799
	❶			❶				❶
			❶	❶	❶	❶
		❶	❶						❶
	❶	❶
					❶	❶	❶
						❶	❶	❶	❶
	❶	❶	❶	❶	❶		❶	❶	❶
\color{grey}i_{R3} = -\frac{S_4 (S_3+ R_3)} {S_3 R_4}	i_{R2} = -\frac{S_4 (S_1+ R_1) (S_3+ R_3)} {R_1 S_3 R_4}	i_5 = \frac{1} {1}
\color{grey} i_{R3} = -\left( 1+ \tfrac{R_3} {S_3} \right) \tfrac{S_4} {R_4}	i_{R2} = -\left( 1+ \tfrac{S_1} {R_1} \right) \left( 1+ \tfrac{R_3} {S_3} \right) \tfrac{S_4} {R_4}
i_{R1} = -\frac{S_4 (S_2+ R_2) (S_3+ R_3)} {S_2 S_3 R_4}	i_1 = \frac{(S_2+ R_2) (S_3+ R_3) (S_4+ R_4)} {S_2 R_3 R_4}
i_{R1} = -\left( 1+ \tfrac{R_2} {S_2} \right) \left( 1+ \tfrac{R_3} {S_3} \right) \tfrac{S_4} {R_4}	i_1 = \left( 1+ \tfrac{R_2} {S_2} \right) \left( 1+ \tfrac{S_3} {R_3} \right) \left( 1+\tfrac{S_4} {R_4} \right)
i_2 = \frac{(S_1+ R_1) (S_3+ R_3) (S_4+ R_4)} {R_1 R_3 R_4}	i_3 = \frac{(S_3+ R_3) (S_4+ R_4)} {R_3 R_4}	i_4 = \frac{S_3+ R_3} {R_3}
i_2 = \left( 1+ \tfrac{S_1} {R_1} \right) \left( 1+ \tfrac{S_3} {R_3} \right) \left( 1+\tfrac{S_4} {R_4} \right)	i_3 = \left( 1+ \tfrac{S_3} {R_3} \right) \left( 1+\tfrac{S_4} {R_4} \right)	i_4 = 1+ \tfrac{S_3} {R_3}
i_6 = \frac{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}	i_7 = \frac{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}
i_6 = \tfrac{1} {1+ \tfrac{\tfrac{R_4} {S_4}} {\left( 1+ \tfrac{R_1} {S_1} \right) \left( 1+\tfrac{R_3} {S_3} \right)}}	i_7 = \tfrac{1} {1+ \tfrac{\tfrac{R_4} {S_4}} {\left( 1+ \tfrac{S_2} {R_2} \right) \left( 1+\tfrac{R_3} {S_3} \right) }}
\color{grey} \mu_{R3} = -\left( 1+ \tfrac{R_3} {S_3} \eta_0 \right) \tfrac{S_4} {R_4} {\eta_0}	\mu_{R2} = -\left( 1+ \tfrac{S_1} {R_1} \eta_0 \right) \left( 1+ \tfrac{R_3} {S_3} \eta_0 \right) \tfrac{S_4} {R_4} \eta_0	\mu_5 {T_{1;5}} = \tfrac{1} {1}
\mu_{R1} = -\left( 1+ \tfrac{R_2} {S_2} {\eta_0}^\tfrac{3} {2} \right) \left( 1+ \tfrac{R_3} {S_3} \eta_0 \right) \tfrac{S_4} {R_4} \eta_0{{efn	name="Eff Rav"	Power flow in gearset 2 (the outer Ravigneaux gearset)	\mu_1 = \left( 1+ \tfrac{R_2} {S_2} {\eta_0}^\tfrac{3} {2} \right) \left( 1+ \tfrac{S_3} {R_3} \eta_0 \right) \left( 1+\tfrac{S_4} {R_4} \eta_0 \right)
\mu_2 = \left( 1+ \tfrac{S_1} {R_1} \eta_0 \right) \left( 1+ \tfrac{S_3} {R_3} \eta_0 \right) \left( 1+\tfrac{S_4} {R_4} \eta_0 \right)	\mu_3 = \left( 1+ \tfrac{S_3} {R_3} \eta_0 \right) \left( 1+\tfrac{S_4} {R_4} \eta_0 \right)	\mu_4 = 1+ \tfrac{S_3} {R_3} \eta_0
\mu_6 = \tfrac{1} {1+ \tfrac{\tfrac{R_4} {S_4} \cdot \tfrac{1} {\eta_0}} {\left( 1+ \tfrac{R_1} {S_1} \eta_0 \right) \left( 1+\tfrac{R_3} {S_3} \eta_0 \right)}}	\mu_7 = \tfrac{1} {1+ \tfrac{\tfrac{R_4} {S_4} \cdot \tfrac{1} {\eta_0}} {\left( 1+ \tfrac{S_2} {R_2} {\eta_0}^\tfrac{3} {2} \right) \left( 1+\tfrac{R_3} {S_3} \eta_0 \right)}}

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 Sport Coupé, C 350 Sport Coupé; post-facelift), (CLC 250, CLC 350)
2007–2011 Mercedes-Benz C-Class (W204) (C 320 CDI)
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 (E 200 AMG 7G-Tronic, E 63 AMG)
2009–2013 Mercedes-Benz W212 (E 200 AMG 7G-Tronic)
2007–2009 Mercedes-Benz W211 (E 230 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

Mercedes CLA-Class

2016–2019 Mercedes-Benz C117

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)
SsangYong Rodius Korando Turismo (in South Korea)
SsangYong Rodius Turismo (in UK)

References

"7G-Tronic: Mercedes-Benz presents the world's first seven-speed automatic transmission for passenger cars". [[DaimlerChrysler]] press release.
Borozan, Ion Silviu. (2014). "Metallographic analysis of the 7G-Tronic automatic gearbox housing". International Journal of Materials.
19 July 2010. "Merc plans nine-speed auto'". Autocar.co.uk.
(2011-04-12). "50 years of automatic transmissions from Mercedes-Benz". media.mercedes-benz.com.
"Mercedes Benz 722.9 Training Manual".
"Mercedes Benz 722.9 Workshop Tips and Tricks Manual".
"Daimler Global Media Site > Mercedes-Benz Cars > AMG".
"The new-generation SLK: More powerful, more economical, more intense | Daimler Global Media Site > Mercedes-Benz Cars > Mercedes-Benz P. Cars > Roadsters > SLK-Class".
"New 7-speed AMG SPEEDSHIFT MCT".
"7G-Tronic Automatic Transmission Catalog (722.9)". Automatic Transmission Rebuilders Association.
"Mercedes-Benz Automatic Transmission 722.9 Technical Training Materials - PDF Free Online".
"First view of Mercedes 2.0 turbo in the Infiniti Q50".
(18 October 2014). "Infiniti Q50 2,2d Sport vs. Mercedes-Benz C220 BlueTEC 7G-tronic".

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