A few days ago, the selection results of the 4th "Longpan Cup" World Top Ten Transmissions sponsored by the Automobile Evaluation Institute were officially released.
has three AT gearboxes, three DCT gearboxes, one CVT gearbox, and three hybrid gearboxes were selected. Like the selection of China's Top Ten Engines, independent brands occupies half of the country. Basically, several top-tier domestic manufacturers take turns in the selection. Let's not evaluate this first.
However, the selected joint venture gearboxes are indeed very powerful, especially the high-end AT gearboxes, which can be regarded as the last technological crystallization of the fuel vehicle era. ZF 8AT, Benz 9AT, and GM 10AT are the representative gearboxes of three major international car companies. What are their outstanding technologies? Let Kung Fu Car take everyone to take a look.
(1) ZF 8AT, the representative of high-end gearboxes
For a long time, ZF's 8AT is almost the representative of high-end gearboxes. In 2007, ZF's first 8AT gearbox came out, and mass production was achieved in 2009. So far it began to appear in various luxury models, becoming one of the representatives of high-end gearboxes. BMW is its biggest customer, Audi and Bentley are also its believers, Land Rover Range Rover , Jeep Grand Cherokee and other big guys are also its supporters.
It can be so successful, naturally thanks to its powerful performance. Although it is an AT gearbox, it has a shifting speed comparable to that of a dual-clutch gearbox. The fastest shifting time is only 0.1 seconds. And not only the dual-clutch "silly fast", its shift logic is also very clear, which is quite good for the field of user intent. The success of the previous generation of BMW models,To a large extent, it is due to the "match made in heaven" between the high-power engine and the ZF 8AT gearbox.
In addition, it also uses a very unique gear ratio design. The larger transmission ratio allows its transmission efficiency to reach 98%, which makes its fuel consumption comparable to that of a manual transmission model. Before it appeared, many people thought that the efficiency of automatic transmissions could not be comparable to that of manual transmissions.
In addition, it supports a double-clutch-like "shift" operation, which can jump straight from 8 to 2 gears. And the torque carrying capacity is also first-class, and off-road vehicles and performance cars also like to use it. Like Great Wall’s Haval H6 and Tank 300, they are among the few self-owned brand models that use ZF 8AT gearboxes.
However, the ZF 8AT is not without its shortcomings. Compared with the Aisin 8AT, its gear ratio design is biased towards medium and high speeds, and the drag gear feel at low speeds is relatively strong. So although it has achieved quite good economy and shifting speed, it still makes a certain sacrifice in some areas of ride comfort.
Also, the 9AT gearbox developed based on ZF 8AT is not a success, especially the frequent occurrence of oil leakage, resulting in ZF’s market share of high-end transverse gearboxes has been unable to increase, and this The block is basically occupied by the Aisin 8AT gearbox.
So although the ZF 8AT gearbox is regarded as a representative of high-end gearboxes, it has the fastest shift speed and good economy. There are some minor problems, but the flaws are not concealed. But the market for rear-drive gearboxes is getting smaller and smaller, and its market influence has been far behind by Aisin 8AT, which I have to say is a pity.
(2) Mercedes-Benz 9AT, the inventor of variable gears?
Compared to Aisin and ZF selling gearboxes everywhere, Mercedes-Benz gearboxes have always been "self-produced and sold". Before the advent of the ZF 8AT, Mercedes-Benz's 7AT was considered the best gearbox on the market, and it was "overtaken on a curve" as a result. As the big brother of the luxury brand, Mercedes-Benz can swallow this breath, so it soon launched the 9AT gearbox,Regained the right to speak in the field of high-end gearboxes.
Because of the 9-speed design, the Mercedes-Benz 9AT has a wider gear ratio range than the ZF 8AT, which makes its high-speed cruise fuel economy very good. Mercedes-Benz 9AT set the gear ratio of first gear to 5.5, which makes it start very quickly. In economic mode, it starts with 2 gears, so the gear ratio of its starting gear becomes 3.33, which makes it more economical than ZF's 8AT. In this way, the first gear of the Mercedes-Benz 9AT has actually become a "sports gear."
Judging from the results, the Mercedes-Benz 9AT has a larger starting gear ratio when exercise is needed, which is faster than the ZF 8AT. In the daily economy mode and comfort mode, it "transforms" into an 8AT gearbox, and the gear ratio design is more compact than the ZF 8AT, more fuel efficient, and smoother shifting.
Through the ingenious Ravenelhe planetary gear design, the Mercedes-Benz 9AT does not increase in volume compared to the old 7AT, and the weight is reduced by 1kg on this basis, and the transmission efficiency is further improved. Although it is not as good as the ZF 8AT in terms of maximum efficiency, since 9AT can start in 2 gears, the new generation of Mercedes-Benz models can basically be equal to BMW's similar models in terms of fuel consumption with larger size and heavier weight. The acceleration performance is better, which is the power of this 9AT.
(3) General 10AT, the most "gentle" high-end multi-speed gearbox
Although general 10AT is the same vertical gearbox as Mercedes-Benz 9AT and ZF 8AT, its design concept But it is very different from the two.
After the great success of 8AT, ZF has also made 9AT and 10AT, but its reputation is far inferior to the original 8AT. To a large extent, it’s because of a problem with ZF’s design thinking.Its 9AT and 10AT, compared with 8AT, the main change is that the gear ratio range is wider, but the gear drop itself has not changed. Take the Range Rover Evoque as an example. Although it has a 9-speed design, users rarely use the highest gear in their daily driving. They still use 8AT or even 7AT in their daily driving.
even sparked a round of discussion about how fast ZF's 9AT can go to 9th gear. It shows that for most users, such a high gear design seems to be a waste. Therefore, there were often such remarks during that period, 8AT was perfect, and no matter how many gears were wasted, GM 10AT refuted this remark with actual performance.
The universal 10AT keeps the gear speed difference at about 20%, which is much lower than ZF's 25%. Although it is a 10-speed design, its gear ratio range is only 7.39, which is the lowest among all gearboxes in its class, and even lower than some 8AT gearboxes.
However, this design brings an advantage. The tight gear ratio design is more conducive to the power of daily driving, and it also greatly improves the smoothness of gear shifting. And because of the dense gear distribution, its shifting speed has also reached a new height. According to the measured data of the previous media, the shift speed of the GM 10AT on the Corvette has surpassed that of the Porsche PDK, and the shift speed of 1-2, 2-3, and 3-4 is even higher than that of the Volkswagen 7DCT gearbox. , It can be called the most common household gearbox.
Of course, because of the small gear ratio range, the economic performance of this gearbox at high speed cruising is slightly weaker than that of the ZF 8AT, but its advantages of smoothness and fast shifting have been unanimously recognized.
(4) Kungfu shot case
The emergence of ZF 8AT has brought the development of gearbox technology to a new level and made it a representative of high-end gearboxes. But Mercedes-Benz 9AT and GM 10AT are not lagging behind. They are actually standing on the shoulders of giants to some extent. Mercedes-Benz 9AT is stronger than ZF 8AT in terms of power and economy because of its wider gear ratio design. , GM 10AT has learned the lessons of ZF’s 9AT and adopted a smaller speed difference design.Have better shifting speed and smoothness.
To some extent, they have achieved the "surpass" of ZF 8AT. But it has to be said that with the development of cars in the direction of electrification, major car companies may no longer invest more energy in the research and development of mechanical gearboxes. Perhaps it is difficult for us to see a better gearbox, which I have to say is a pity.
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