ABSTRACT We have developed the world's first 8-speed automatic transmission for transverse FWD/4WD vehicles. The aim of this new automatic transmission was to achieve world-class fuel economy while offering both smooth gear shift and sporty shift feeling suitable for luxury cars. This has been accomplished using wide spread gear ratio, outstanding low drag components and highly efficient hydraulic control system. In addition, we have achieved the compactness similar to current 6-speed automatic transmission by adopting new gear train and compact clutch layout. In this paper, the detail of this automatic transmission is introduced. INTRODUCTION Because of recent global energy and environment issues, it has become essential to develop cars with a greater degree of fuel economy and cleaner exhaust gas. At the same time, more high driving performance is demanded for premium car. Technology which can combine both of above apparently conflicting features is now being sought. In FWD car market, in order to improve fuel economy and acceleration performance, first 6-speed automatic transmission was introduced in 2002, i.e. 11 years ago. After that, most of high-class FWD vehicles have adopted 6-speed automatic transmission year by year. However, in order to conform to the regulation which becomes severe every year, the further improvement in fuel economy became indispensable. Meanwhile, another type of automatic transmission had been applied to some vehicles, and people have been discussing which type of stepped-automatic transmission is better solution.On the other hand, for further fuel economy and driving performance, RWD vehicle has adopted 8-speed automatic transmission since 2006. However for FWD vehicles, it was difficult to adopt 8-speed automatic transmission because of its enlarged size due to increased component number. Under these backgrounds, we developed the world's first transverse 8-speed automatic transmission as the best solution for high-class luxury transverse FWD/4WD vehicles. In order to achieve world's class fuel economy, we adopted “wide and close” gear ratio, and reduced transmission loss thoroughly. At the same time, we realized compactness by adopting the new gear train and the new clutch structure. Furthermore, by adopting torque converter and conventional type shift elements, each of smooth gear shifting, sportiness and drivability are consisted at high level. In this paper, the characteristics of the structure, performance, and the functionality of this new automatic transmission are described. STRUCTURE Torque converter, oil pump, gear train and shift elements are located in 1st axis. And counter shaft is arranged in 2nd axis, differential gear is arranged in 3rd axis. Valve body is positioned in front side of vehicle. Gear Train In general terms, in order to achieve multiple speeds, the transmission size must be increased as a result of the increased numbers of planetary gear sets and shift elements. On the other hand, due to the limited package space in FWD vehicles, the new automatic transmission was required to The World's First Transverse 8-Speed Automatic Transmission2013-01-1274 Published 04/08/2013 Toshihiko Aoki and Hiroshi Kato Aisin AW Co Ltd Naoki Kato and Morise Masaru Toyota Motor Corp. Copyright © 2013 SAE International doi:10.4271/2013-01-1274Downloaded from SAE International by Birmingham City Univ, Tuesday, August 21, 2018have the same or less size than the current 6-speed automatic transmission. We introduced a new gear train concept which can constitute 8-speeds by a minimum number of the elements, i.e. adding only one shift element to the current 6-speed automatic transmission. (The number of planetary gear sets is unchanged.) Table 1 shows the technical data of new 8-speed automatic transmission. Table 1. Technical data of new transmission The new 8-speed automatic transmission is structured with only two planetary gear sets (Front planetary and Rear planetary), four clutc