Audi, which has worked hard in China automobile market for many years, has established an unshakable position in people's minds. Audi impressed us deeply with its noble quality and advanced technology. From the high-end A8L to the low-end A3, from the bold SUV to the dynamic and passionate sports car, the shadow of Audi's advanced technology is everywhere. Audi is the most technologically advanced among the three major German automobile companies. Audi has also attracted many consumers through its leading position in technology. Audi's advanced full-time four-wheel drive technology is also one of the most noteworthy technologies in Audi's leading position. Different from other models, models adopting this technology will be labeled as Quattro. From A3 to A8L, Audi spared no effort to praise its models with Quattro's logo. After all, Quattro can truly reflect Audi's advanced technology. It is also the success of Audi's commercialization of racing technology. When Quattro first appeared in people's sight, it was famous for its core component-full-time four-wheel drive system-Torsten differential. It is also this advanced full-time four-wheel drive system that makes Quattro's advanced nature deeply rooted in people's hearts. But our questions arise from this. As a small family car, the main purpose of Audi A3 is to meet people's daily use and provide convenience for people's travel. Is it necessary to use full-time four-wheel drive technology for such a small car? On the other hand, Audi's new TT, as a sports model for sports advertising, has also been labeled as Quattro. There is no doubt that the sports car is equipped with full-time four-wheel drive technology. But the facts seem to fool our wisdom. One of the highlights of the new TT is not its unique full-time four-wheel drive technology, but it is called intelligent four-wheel drive technology. Why did Audi give up its most beautiful full-time four-wheel drive technology in publicity? In fact, it is precisely because we have confused the full-time four-wheel drive system with Quattro's logo. Although Audi A3 and the new TT are labeled with Quattro, they are completely different from Audi's unique full-time four-wheel drive technology. This quartet is not another quartet. Due to the excellent performance of the TOSON central differential, it is generally believed that Audi marked with Quattro is the representative of high performance, which is not entirely correct, because Quattro itself is different. People are most likely to associate the QUATTRO logo with Audi's unique full-time four-wheel drive technology. Torsen center differential is the core of this full-time four-wheel drive technology. For the traditional open differential structure, the power will always be transmitted to the wheels with the least resistance (slipping and idling wheels), which leads to the failure of the car to run normally. After adopting the Torsten central differential, the differential adopts a unique planetary gear structure composed of double turbines and worms, which has the function of automatic differential locking. This ingenious structural design is the most magical part of the Torsten differential, which can automatically distribute the torque to the wheels with good adhesion and ensure the car to get out of trouble. Its function is completely equivalent to a differential with a central differential lock. However, Tolson differential is not absolutely perfect. It is precisely because of its pure mechanical transmission structure that it will lose a lot of power in power consumption, which is why Audi A4 3.0 Quattro can't let us feel its strong power. Therefore, the Torsen central differential must be driven by a powerful large displacement engine. This also limits the application of Torsen central differential in small displacement vehicles. We can see that Audi A4 and above models, including Q7, all adopt the arrangement of front longitudinal engine, and the gearbox and engine are connected in series. The power of the engine can be directly transmitted to the transmission shaft through the gearbox, and then transmitted to the front and rear axles through the central differential. The power of the engine with this structure can be directly transmitted to the central differential without any gear structure to change the direction of power transmission. However, the transverse engine structure is not, so it is impossible to arrange the Tolson differential. Therefore, the QUATTRO used for TT, A3 and other vehicles with horizontal engine front platform is a timely four-wheel drive based on Haldex multi-disc clutch, and its technical structure and principle are the same as those of most urban SUVs. Power is first transmitted to the front axle, and then to the rear axle through the multi-disc clutch. When the four-wheel drive mode is needed, a plurality of clutches are connected to transfer part of the power of the front axle to the rear axle to realize the four-wheel drive mode. Due to the limitation of clutch efficiency, the four-wheel drive mode of Haldex multi-disc clutch will lead to long-term overheating of clutch plates and loss of driving force, which is not suitable for heavy-duty vehicles. For small cars, such as Audi tt and A3, the timely four-wheel drive mode of multi-disc clutch can just meet the demand of improving vehicle driving performance. The QUATTRO used by TT and A3 is completely different from the QUATTRO equipped above A4 in terms of structural principle and actual performance. In fact, QUATTRO itself is not what everyone thinks, it is Audi's unique full-time four-wheel drive system. Audi Quattro is actually not the name of any system, but the name of a modification factory of Audi. It's good.