| 9G-Tronic | |
| Production: | 2013–present |
| Manufacturer: | Daimler AG Jatco Ltd |
| Class: | 9-speed longitudinal automatic transmission |
| Related: | ZF 8HP · Aisin-Toyota 8-speed · Ford-GM 10-speed |
| 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 700Nm maximum input torque; type 725.0[1]) as core model. The transmission debuted on the E 350 BlueTEC in 2013, 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 1000Nm.[2]
After the 5G- and 7G-Tronic, this is the 3rd generation of modern automatic transmissions. Therefore this transmission is identified internally as NAG3 (New Automatic Gearbox 3rd generation).[3] In order to increase the number of ratios, the previous restriction to the design as a pure in-line transmission has been abandoned and combined with that of the parallel epicyclic gearing.
Development took place at the group's headquarters in Stuttgart-Untertuerkheim. Initially, the transmission was produced only at the Daimler plant not far away in Stuttgart-Hedelfingen. Since April 2016, the transmission has also been produced at Daimler's subsidiary Star Assembly in Sebeș, Romania.[4]
In 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 Nm, allowing each of the gearsets 1, 2, and 4 to use only three planetary gears.[7] Slightly modified gear dimensions give it a span of about 9.09:1.
The other 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. It has a torque converter lock-up clutch and a twin-turbine harmonic damper with centrifugal pendulum absorber technology.[8] The torque converter lock-up can operate in all 9 forward gears.
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%.
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 electic DC motor. 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. 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 made its debut 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.[9] The MCT acronym refers to the planetary transmission's multiple clutches and brakes. Its torque is rated at 900Nm and it offers 4 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 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 driver benefits from extremely short shift/response times. Fast multiple downshifts and the double-clutching function make for a highly emotive gearshift experience.
The main objective for the replacement of the predecessor model was to realize at least one additional gear and save at least one shift element. Progress is reflected in 9 forward gears using 10 main components,[10] compared to 7 forward gears with 11 main components of the direct predecessor.[11] This was only possible thanks to computer-aided design and has resulted in a globally patented gearset concept. In the process, 85 billion gearset concepts were examined.[12] This means that the gearbox requires the same installation space as the previous model and is also 1kg (02lb) lighter.
The wide gear span allows the engine speed level to be lowered (downspeeding), which is a decisive factor in improving energy efficiency and thus reducing fuel consumption. 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). 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] By the end of 2024 unsurpassed ratio span among longitudinal automatic transmissions for passenger cars.
| Weight | Planetary Gearset: Teeth | Count | Total Center | Avg. | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Simpson | Simple | |||||||||
| Model Type | Version First Delivery | with Con- verter + Oil | S1 R1 | S2 R2 | S3 R3 | S4 R4 | Brakes Clutches | Ratio Span | Gear Step | |
| Gear Ratio | R {iR} | 1 {i1} | 2 {i2} | 3 {i3} | 4 {i4} | 5 {i5} | 6 {i6} | 7 {i7} | 8 {i8} | 9 {i9} |
| Step | -\tfrac{iR}{i1} | \tfrac{i1}{i1} | \tfrac{i1}{i2} | \tfrac{i2}{i3} | \tfrac{i3}{i4} | \tfrac{i4}{i5} | \tfrac{i5}{i6} | \tfrac{i6}{i7} | \tfrac{i7}{i8} | \tfrac{i8}{i9} |
| Δ Step | \tfrac{i1}{i2}:\tfrac{i2}{i3} | \tfrac{i2}{i3}:\tfrac{i3}{i4} | \tfrac{i3}{i4}:\tfrac{i4}{i5} | \tfrac{i4}{i5}:\tfrac{i5}{i6} | \tfrac{i5}{i6}:\tfrac{i6}{i7} | \tfrac{i6}{i7}:\tfrac{i7}{i8} | \tfrac{i7}{i8}:\tfrac{i8}{i9} | |||
| Shaft Speed | \tfrac{i1}{iR} | \tfrac{i1}{i1} | \tfrac{i1}{i2} | \tfrac{i1}{i3} | \tfrac{i1}{i4} | \tfrac{i1}{i5} | \tfrac{i1}{i6} | \tfrac{i1}{i7} | \tfrac{i1}{i8} | \tfrac{i1}{i9} |
| Δ Shaft Speed | 0-\tfrac{i1}{iR} | \tfrac{i1}{i1}-0 | \tfrac{i1}{i2}-\tfrac{i1}{i1} | \tfrac{i1}{i3}-\tfrac{i1}{i2} | \tfrac{i1}{i4}-\tfrac{i1}{i3} | \tfrac{i1}{i5}-\tfrac{i1}{i4} | \tfrac{i1}{i6}-\tfrac{i1}{i5} | \tfrac{i1}{i7}-\tfrac{i1}{i6} | \tfrac{i1}{i8}-\tfrac{i1}{i7} | \tfrac{i1}{i9}-\tfrac{i1}{i8} |
| W9A ALL 725.0 | 1000Nm 2013 | 95kg (209lb) | 46 98 | 44 100 | 36 84 | 34 86 | 3 3 | |||
| Gear Ratio | \tfrac{6,835}{1,242} | \tfrac{10}{3} | \tfrac{125}{54} | \tfrac{1,075}{888} | \tfrac{58,781}{67,944} | \tfrac{43}{60} | \tfrac{52,675}{87,576} | |||
| Step | 1.0000 | 1.6510 | 1.4400 | 1.3722 | 1.2106 | 1.2072 | 1.1915 | |||
| Δ Step | 1.1465 | 1.0333 | 1.1335 | 1.0473 | 1.0131 | |||||
| Speed | 1.0000 | 1.6510 | 2.3774 | 3.3130 | 4.5459 | 7.6789 | 9.1495 | |||
| Δ Speed | 1.0000 | 0.6510 | 0.7264 | 0.9356 | 1.2329 | 1.3178 | 1.4706 | |||
| W9A ALL 725.0 | 1000Nm 2016 | 95abbr=onNaNabbr=on | 46 98 | 44 100 | 37 83 | 34 86 | 3 3 | |||
| Gear Ratio | \tfrac{13,670}{2,553} | \tfrac{120}{37} | \tfrac{250}{111} | \tfrac{1,075}{888} | \tfrac{43}{60} | \tfrac{52,675}{87,576} | ||||
| Step | 1.0000 | 1.6510 | 1.4400 | 1.3511 | 1.2106 | 1.2072 | 1.1915 | |||
| Δ Step | 1.1465 | 1.0457 | 1.1160 | 1.0473 | 1.0131 | |||||
| Speed | 1.0000 | 1.6510 | 2.3774 | 3.2737 | 4.4231 | 7.4714 | 8.9022 | |||
| Δ Speed | 1.0000 | 0.6510 | 0.7264 | 0.8964 | 1.1493 | 1.2822 | 1.4308 | |||
| Jatco 9AT JR913E | 700Nm 2019 | 99.5kg (219.4lb)[14] | 45 96 | 41 91 | 38 86 | 37 92 | 3 3 | |||
| Gear Ratio | \tfrac{51,026}{9,405} | \tfrac{62}{19} | \tfrac{2,821}{1,254} | \tfrac{8,372}{6,855} | \tfrac{92}{129} | \tfrac{66,976}{112,227} | ||||
| Step | 1.0000 | 1.6626 | 1.4505 | 1.3503 | 1.2213 | 1.2085 | 1.1950 | |||
| Δ Step | 1.1462 | 1.0634 | 1.1056 | 1.0526 | 1.0113 | |||||
| Speed | 1.0000 | 1.6626 | 2.4117 | 3.2899 | 4.4423 | 7.6074 | 9.0910 | |||
| Δ Speed | 1.0000 | 0.6626 | 0.7491 | 0.8782 | 1.1525 | 1.3124 | 1.4836 | |||
| Ratio R & Even | iR=-\tfrac{R1R2(S3+R3)}{S1(S2+R2)S3} | i2=\tfrac{S3+R3}{S3} | \tfrac{S3(S4+R4)+R3S4}{S3(S4+R4)} | i6=\tfrac{1}{1} | i8=\tfrac{R4}{S4+R4} | |||||
| Ratio Odd | \tfrac{(S1(S2+R2)+R1S2)(S3+R3)}{S1(S2+R2)S3} | i3=\tfrac{R2(S3+R3)}{(S2+R2)S3} | i5=\tfrac{R2R4}{R2R4-S2S4} | \tfrac{R4(S1(S2+R2)+R1S2)}{S1R4(S2+R2)+R1S2(S4+R4)} | \tfrac{R1R2R4}{S1S4(S2+R2)+R1R2(S4+R4)} | |||||
| Algebra And Actuated Shift Elements | ||||||||||
| Brake A | ❶ | ❶ | ❶ | |||||||
| Brake B | ❶ | ❶ | ❶ | (❶) | ❶ | ❶ | ❶ | |||
| Brake C | ❶ | ❶ | ❶ | ❶ | ❶ | |||||
| Clutch D | ❶ | ❶ | ❶ | ❶ | ||||||
| Clutch E | ❶ | ❶ | ❶ | ❶ | ❶ | |||||
| Clutch F | ❶ | ❶ | ❶ | ❶ | ❶ | ❶ | ||||
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. This applies, for example, to the oil filters permanently integrated in the plastic oil pan. 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.
▶️ 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,[15] 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)