9G-Tronic
Cutaway model of the transmission with components for hybrid drive
Overview
Manufacturer	Daimler AG Jatco Ltd
Production	2013–present
Body and chassis
Class	9-speed longitudinal automatic transmission
Related	ZF 8HP · Aisin-Toyota 8-speed · Ford-GM 10-speed
Chronology
Predecessor	7G-Tronic

9G-Tronic is Mercedes-Benz's trademark name for its 9-speed automatic transmission, starting off with the W9A 700 (Wandler-9-Gang-Automatik bis 700 N⋅m Eingangsdrehmoment; converter-9-gear-automatic with 700 N⋅m (516 lb⋅ft) maximum input torque; type 725.0^[1]) as core model. The transmission was used in the E 350 BlueTEC in 2013 for the first time,^[1] and successively replaced both the 7-speed 7G-Tronic (PLUS) transmission and the 5-speed 5G-Tronic transmission. It includes versions for a maximum input torque of 1,000 N⋅m (738 lb⋅ft).^[2]

After the 5G- and 7G-Tronic, this is the 3rd generation of modern automatic transmissions. It is identified internally as NAG3 (New Automatic Gearbox 3rd generation).^[3]

The Jatco 9AT transmission is based on the same globally patented gearset concept.

Development took place at the group's headquarters in Stuttgart-Untertuerkheim.^[1] Initially, the transmission was produced only at the Daimler plant not far away in Stuttgart-Hedelfingen.^[3] Since April 2016, the transmission has also been produced at Daimler's subsidiary Star Assembly in Sebeș, Romania.^[4]

ln 2019, the Jatco Ltd, based in Fuji, Shizuoka, Japan, started licensed production for use in Nissan and Infiniti vehicles.^[5][6] In this version, input torque is limited to 700 N⋅m (516 lb⋅ft),^[7] allowing each of the gearsets 1, 2, and 4 to use only three planetary gears.^[8] Slightly modified gear dimensions give it a span of just under 9.1:1.

One main focus was on increasing shift comfort, which is achieved on the one hand by measures in the control system and on the other hand by designing the torque converter accordingly. The hydrodynamic torque converter was largely taken over from the previous 7G-Tronic transmission.

The 9G-Tronic is fully electronically controlled. The shift elements are controlled via a new type of hydraulic direct control with electromagnetically actuated valves, which enables fast and smooth gear changes. Compared to the previous transmission, which had a hydraulic pilot control, leakage losses have been reduced by 80%.^[10]

The transmission is equipped with two oil pumps to ensure an energy-efficient supply of long-life synthetic fuel-economy low-friction oil: a mechanical rotary vane pump with chain drive, which is significantly smaller than its predecessor and located next to the main shaft, and a pump driven by a brushless electric DC motor.^[10] The mechanically driven pump is responsible for the basic supply of the transmission, with the flow rate depending on the speed of the drive motor. The additional pump is switched on by the electronic transmission control unit as required. This design enables the lubricating and cooling oil volume flow to be regulated as required and makes the 9G-Tronic start/stop-capable.^[1] When the drive motor is at a standstill, the transmission remains ready to start solely due to the supply from the electric auxiliary pump.

Filter elements for the two pumps are integrated in the plastic oil pan.

The TCT 9G (Torque Converter Technology) transmission is essentially the 9G-Tronic.

Mercedes-AMG developed the MCT 9G (Multi Clutch Technology) transmission. It was first introduced in the Mercedes-AMG E 63 4Matic+.

The MCT transmission is essentially the 9G-Tronic with a start-off wet clutch (NAK for German Nass-Anfahrkupplung) replacing the torque converter. This saves weight and optimises the response to the accelerator pedal input. It is a computer-controlled double-clutching.^[11] The MCT acronym refers to this multiple-plate clutch. Its torque is rated at 900 N⋅m (664 lb⋅ft) and it offers 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 as the central control unit for all driving dynamics functions and an innovative Race Start Function.

The driver can change gears either using the steering-wheel shift paddles or conventionally the selector lever. The new Race Start Function is a launch control system that enables maximum acceleration while ensuring optimum traction of the driven wheels.

The main objectives in replacing the previous 7G-Tronic model were to improve fuel consumption by adding gears and increasing the gear span, while at the same time reducing manufacturing costs.

The wide gear span^[a] allows the engine speed level to be lowered (downspeeding), which is a decisive factor in improving energy efficiency and thus reducing fuel consumption by 6.5 %.^[10] In addition, the lower engine speed level improves the noise-vibration-harshness comfort and the exterior noise is reduced by up to 4 dB(A).^[1] A speed of 120 km/h is reached in the Mercedes-Benz E 350 BlueTEC in 9th gear at an engine speed of approx. 1350 rpm.^[13] Unsurpassed ratio span among longitudinal automatic transmissions for passenger cars.^[b]

As the design of the predecessor was significantly more complex than that of the direct competitor 6HP and even the new 8HP model from ZF with one more gear, the specification sheet also stipulate that at least one shift element must be omitted. This was achieved thanks to high-speed computer-aided design and has resulted in a globally patented gearset concept that requires the same installation space as the previous model and is also 1 kg (2.2 lb) lighter.^[2] In the process, 85 billion gearset concepts were examined.^[14] Additionally, the unit brings the ability to shift in a non-sequential manner – going from gear 9 to gear 4 in extreme situations simply by changing one shift element (actuating brake C and releasing brake A).

After the 5G- and 7G-Tronic, this transmission is the 3rd generation^[3] in which in-line epicyclic gearing have been combined with parallel epicyclic gearing. The resulting progress is reflected in an even better ratio between the number of gears and the number of components used compared to all layouts previously used by Mercedes-Benz.

Innovation Strength

With Asessment	Output: Gear Ratios	Innovation Elasticity[a] Δ Output : Δ Input	Input: Main Components
			Total	Gearsets	Brakes	Clutches
W9A Ref. Object		Topic[a]
Δ Number
Relative Δ	Δ Output	·	Δ Input
W9A W7A[b]	9[c] 7[d]	Progress[a]	10 11[15]	4 4[e]	3 4	3 3
Δ Number	2		-1	0	-1	0
Relative Δ	0.286	−3.143[a] ·	−0.091	0.000	−0.250	0.000
W9A 8HP[f]	9[c] 8[c]	Current Market Position[a]	10 9	4 4	3 2	3 3
Δ Number	1		1	0	1	0
Relative Δ	0.125	1.125[a] ·	0.111	0.000	0.500	0.000
W9A 3-Speed[g]	9[c] 3[c]	Historical Market Position[a]	10 7	4 2	3 3	3 2
Δ Number	6		3	2	0	1
Relative Δ	2.000	4.667[a] ·	0.429	1.000	0.000	0.500
^ a b c d e f g h Innovation Elasticity Classifies Progress And Market Position Automobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraints Only innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realization The required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientation negative, if the output increases and the input decreases, is perfect 2 or above is good 1 or above is acceptable (red) below this is unsatisfactory (bold) ^ Direct Predecessor To reflect the progress of the specific model change ^ a b c d e plus 1 reverse gear ^ plus 2 reverse gears ^ of which 2 gearsets are combined as a compound Ravigneaux gearset ^ Current Reference Standard (Benchmark) The 8HP has become the new reference standard (benchmark) for automatic transmissions ^ Historical Reference Standard (Benchmark) 3-speed transmissions with torque converters have established the modern market for automatic transmissions and thus made it possible in the first place, as this design proved to be a particularly successful compromise between cost and performance It became the archetype and dominated the world market for around 3 decades, setting the standard for automatic transmissions. It was only when fuel consumption became the focus of interest that this design reached its limits, which is why it has now completely disappeared from the market What has remained is the orientation that it offers as a reference standard (point of reference, benchmark) for this market for determining progressiveness and thus the market position of all other, later designs All transmission variants consist of 7 main components Typical examples are Turbo-Hydramatic from GM Cruise-O-Matic from Ford TorqueFlite from Chrysler Detroit Gear from BorgWarner for Studebaker BW-35 from BorgWarner and as T35 from Aisin 3N 71 from Nissan/Jatco 3 HP from ZF Friedrichshafen W3A 040 and W3B 050 from Mercedes-Benz

The ratios of the 9 gears are better distributed in all versions than in the direct competitors 8HP from ZF and much better than in the 10-speed transmissions from Ford/GM and Aisin/Toyota. The only noticable weaknesses are the relativly small step between 5th and 6th gear and the too small one between 6th and 7th gear. These cannot be eliminated without affecting all other gears and thus impairing gear steps. On the other hand, this weaknesses are not overly significant.

All in all

• the extra effort, reflected in the acceptable elasticity compared to the ZF 8HP is more than justified and
• compared to the 10-speed gearboxes from Ford/GM and Aisin/Toyota, the absence of the 10th gear is more than compensated for by the significantly better distribution.

Gear Ratios

With Assessment			Weight	Planetary Gearset: Teeth[a]				Count	Total[b] Center[c]	Avg.[d]
				Simpson		Simple[e]
Model Type	Version First Delivery		with Con- verter + Oil	S1[f] R1[g]	S2[h] R2[i]	S3[j] R3[k]	S4[l] R4[m]	Brakes Clutches	Ratio Span	Gear Step[n]
Gear Ratio	R	1	2	3	4	5	6	7	8	9
Step[n]	[o]		[p]
Δ Step[q][r]
Shaft Speed
Δ Shaft Speed[s]
Torque Ratio[t]
Efficiency[t]	ηR	η1	η2	η3	η4	η5	η6	η7	η8	η9
W9A ALL 725.0	1,000 N⋅m (738 lb⋅ft)[2] 2013[u]		94.8 kg (209 lb)[9]	46 98	44 100	36 84	34 86	3 3	9.1495 1.8194	1.3188[n]
Gear Ratio	−4.9316[o]	5.5032	3.3333	2.3148	1.6611[r]	1.2106	1.0000[s]	0.8651[r][s]	0.7167	0.6015
Step	0.8961[o]	1.0000	1.6510	1.4400	1.3935	1.3722	1.2106	1.1559	1.2072	1.1915
Δ Step[q]			1.1465	1.0333	1.0156[r]	1.1335	1.0473	0.9575[r]	1.0131
Speed	-1.1159	1.0000	1.6510	2.3774	3.3130	4.5459	5.5032	6.3611	7.6789	9.1495
Δ Speed	1.1159	1.0000	0.6510	0.7264	0.9356	1.2329	0.9573[s]	0.8579[s]	1.3178	1.4706
Torque[t]	–4.6393	5.2806	3.2633	2.2450	1.6274	1.1957	1.0000	0.8578	0.7104	0.5902
Efficiency[t]	0.9407	0.9595	0.9790	0.9698	0.9797	0.9877	1.0000	0.9915	0.9913	0.9813
W9A ALL 725.0	1,000 N⋅m (738 lb⋅ft)[2] 2016[u]		94.8 kg (209 lb)[9]	46 98	44 100	37 83	34 86	3 3	8.9022 1.7946	1.3143[n]
Gear Ratio	−4.7983[o]	5.3545	3.2432	2.2523	1.6356[r]	1.2106	1.0000[s]	0.8651[r][s]	0.7167	0.6015
Step	0.8961[o]	1.0000	1.6510	1.4400	1.3770	1.3511	1.2106	1.1559	1.2072	1.1915
Δ Step[q]			1.1465	1.0457	1.0192[r]	1.1160	1.0473	0.9575[r]	1.0131
Speed	-1.1159	1.0000	1.6510	2.3774	3.2737	4.4231	5.3545	6.1892	7.4714	8.9022
Δ Speed	1.1159	1.0000	0.6510	0.7264	0.8964	1.1493	0.9314[s]	0.8347[s]	1.2822	1.4308
Torque[t]	–4.5151	5.1392	3.1759	2.1849	1.6031	1.1957	1.0000	0.8578	0.7104	0.5902
Efficiency[t]	0.9410	0.9598	0.9793	0.9701	0.9802	0.9877	1.0000	0.9915	0.9913	0.9813
Jatco 9AT JR913E	700 N⋅m (516 lb⋅ft) 2019[v]		99.5 kg (219 lb)[7]	45 96	41 91	38 86	37 92	3 3	9.0910 1.7994	1.3177[n]
Gear Ratio	−4.7991[o]	5.4254	3.2632	2.2496	1.6491[r]	1.2213	1.0000[s]	0.8619[r][s]	0.7132	0.5968
Step	0.8846[o]	1.0000	1.6626	1.4505	1.3641	1.3503	1.2213	1.1603	1.2085	1.1950
Δ Step[q]			1.1462	1.0634	1.0102[r]	1.1056	1.0526	0.9601[r]	1.0113
Speed	-1.1305	1.0000	1.6626	2.4117	3.2899	4.4423	5.4254	6.2950	7.6074	9.0910
Δ Speed	1.1305	1.0000	0.6626	0.7491	0.8782	1.1525	0.9831[s]	0.8696[s]	1.3124	1.4836
Torque[t]	–4.5149	5.2061	3.1953	2.1818	1.6161	1.2055	1.0000	0.8544	0.7069	0.5855
Efficiency[t]	0.9408	0.9596	0.9792	0.9699	0.9800	0.9871	1.0000	0.9914	0.9912	0.9810
Ratio R & Even					[e]
Ratio Odd
Algebra And Actuated Shift Elements[w]
Brake A[x]	❶								❶	❶
Brake B[y]	❶	❶		❶	(❶)[z]	❶		❶		❶
Brake C[aa]	❶	❶	❶	❶	❶[e]
Clutch D[ab]			❶	❶		❶	❶
Clutch E[ac]		❶	❶				❶	❶	❶
Clutch F[ad]					❶[e]	❶	❶	❶	❶	❶
^ Layout Input and output are on opposite sides Planetary gearset 1 is on the input (turbine) side Input shafts are S1, C4 (planetary gear carrier of gearset 4), and, if actuated, C1 (planetary gear carrier of gearset 1) Output shaft is C3 (planetary gear carrier of gearset 3) ^ Total Ratio Span (Total Ratio Spread · Total Gear Ratio) A wider span enables the downspeeding when driving outside the city limits increase the climbing ability when driving over mountain passes or off-road or when towing a trailer ^ Ratio Span's Center The center indicates the speed level of the transmission Together with the final drive ratio it gives the shaft speed level of the vehicle ^ Average Gear Step With decreasing step width the gears connect better to each other shifting comfort increases ^ a b c d Except in 4th gear when used in the Simpson configuration ^ Sun 1: sun gear of gearset 1 ^ Ring 1: ring gear of gearset 1 ^ Sun 2: sun gear of gearset 2 ^ Ring 2: ring gear of gearset 2 ^ Sun 3: sun gear of gearset 3 ^ Ring 3: ring gear of gearset 3 ^ Sun 4: sun gear of gearset 4 ^ Ring 4: ring gear of gearset 4 ^ a b c d e Standard 50:50 — 50 % Is Above And 50 % Is Below The Average Gear Step — With steadily decreasing gear steps (yellow highlighted line Step) and a particularly large step from 1st to 2nd gear the lower half of the gear steps (between the small gears; rounded down, here the first 4) is always larger and the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smaller than the average gear step (cell highlighted yellow two rows above on the far right) lower half: smaller gear steps are a waste of possible ratios (red bold) upper half: larger gear steps are unsatisfactory (red bold) ^ a b c d e f g Standard R:1 — Reverse And 1st Gear Have The Same Ratio — The ideal reverse gear has the same transmission ratio as 1st gear no impairment when maneuvering especially when towing a trailer a torque converter can only partially compensate for this deficiency Plus 11.11 % minus 10 % compared to 1st gear is good Plus 25 % minus 20 % is acceptable (red) Above this is unsatisfactory (bold) ^ Standard 1:2 — Gear Step 1st To 2nd Gear As Small As Possible — With continuously decreasing gear steps (yellow marked line Step) the largest gear step is the one from 1st to 2nd gear, which for a good speed connection and a smooth gear shift must be as small as possible A gear ratio of up to 1.6667:1 (5:3) is good Up to 1.7500:1 (7:4) is acceptable (red) Above is unsatisfactory (bold) ^ a b c d From large to small gears (from right to left) ^ a b c d e f g h i j k l m Standard STEP — From Large To Small Gears: Steady And Progressive Increase In Gear Steps — Gear steps should increase: Δ Step (first green highlighted line Δ Step) is always greater than 1 As progressive as possible: Δ Step is always greater than the previous step Not progressively increasing is acceptable (red) Not increasing is unsatisfactory (bold) ^ a b c d e f g h i j k l m Standard SPEED — From Small To Large Gears: Steady Increase In Shaft Speed Difference — Shaft speed differences should increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one 1 difference smaller than the previous one is acceptable (red) 2 consecutive ones are a waste of possible ratios (bold) ^ a b c d e f g h Torque Ratio And Efficiency Ratio of output torque to input torque Assumed efficiency η0 of the combined epicyclic meshing for Assumed efficiency η0 of a single meshing: ^ a b First version with a gear ratio span wider than 9.1:1.[12] Was replaced by a slightly more narrowly stepped 2nd version with the introduction of the Mercedes-Benz E-Class (W213) series in 2016 without announcement to reduce the step between gear 4 and 5 below the one of the 7G-Tronic (1.3684:1 [26:19])[16] AMG SpeedShift MCT 9G is rated at 900 N⋅m (664 lb⋅ft)[11] ^ Under license from Daimler[17] ^ Permanently coupled elements R1 and C2 R2, S3, and S4 ^ Blocks C1 (carrier 1) ^ Blocks S2 ^ Not involved. Only serves to maintain the shift logic: only one shift element is changed for step up or down ^ Blocks R3 ^ Couples S1 with C1 (carrier 1) ^ Couples C1 (carrier 1) with R2 ^ Couples C3 (carrier 3) with R4

Compared to the predecessor gearboxes NAG1 (5G-Tronic) and NAG2 (7G-Tronic), the NAG3 gearbox is much more highly integrated, meaning that repairs are only possible by replacing entire assemblies when servicing is required.^[1] This applies, for example, to the oil filters permanently integrated in the plastic oil pan.^[12] Another example is the fully integrated mechatronic module with sensors, control unit and electrohydraulic shift plate. This module must be replaced as a unit, even if, for example, only one sensor is defective.^[12]

▶️ Interactive Nomogram

This nomogram is a real geometric calculator exactly representing the rotational speeds of the transmission's 3x4 = 12 internal shafts for each of its 9 ratios (+ reverse), grouped according to their 4 permanent coupling on 3 joint ordinates and 5 independent ordinates. These ordinates are positioned on the abscissa in strict accordance with the proportions of the sun gears' teeth numbers relative to those of their rings. Consequently, the output ratios on the 3rd ordinate (carrier of the third planetary gearset) follows closely those of the actual transmission. This advantageous geometric construction sets us free from Robert Willis' famous and tedious formula,^[18] because all calculations are exclusively determined by lengths ratios, respectively teeth numbers on the abscissa for the 4 epicyclic ratios, and of rotational speeds on the 3rd ordinate for the 10 gear ratios.

This nomogram reflects the version from 2013.

A: Brake (blocks S₂ sun gear)
B: Brake (blocks R₃ ring gear)
C: Brake (blocks C₁ carrier gear)
D: Clutch (couples C₃ carrier gear with R₄ ring gear)
E: Clutch (couples C₁ carrier gear with R₂ ring gear)
F: Clutch (couples S₁ sun gear with C₁ carrier gear)

• 2018–2021 Mercedes-Benz W205 (all models)
• 2022–present Mercedes-Benz W206

• 2014–2016 Mercedes-Benz W212 (E 350 BlueTec only) available as an option to others.
• 2016–2023 Mercedes-Benz W213
• 2023–present Mercedes-Benz W214

• 2015–2021 Mercedes-Benz W222 (all except V12 models)
• 2021–present Mercedes-Benz W223

• 2020–present V-Class (W447) (longitudinal engines)

• 2015–2022 GLC (X253)
• 2022–present GLC (X254)

• 2016–2019 GLE (W166) (except 63 AMG & 350 models)
• 2020–present GLE (W167) (except 63 models)

• 2017–2019 GLS (X166) (all except AMG)
• 2020–present GLS (X167)

• 2015–2020 SLC (R172) (except 55 AMG)

• 2022–present AMG SL (R232)

• 2020–2024 Nissan Titan
• 2020–present Nissan Frontier
• 2023–present Nissan Z (RZ34)

• 2021–present Aston Martin DBX

• List of Daimler AG transmissions
• List of Jatco transmissions

• Nine-Speed Automatic Transmission 9G-Tronic by Mercedes-Benz
• Nomographs and Feasibility Graphs for Enumeration of Ravigneaux-Type Automatic Transmissions