Abstract The new eight-speed automatic transmission direct shift-8AT (UA80) is the first automatic transmission to be developed based on the Toyota New Global Architecture (TNGA) design philosophy. Commonizing or optimizing the main components of the UA80 enables compatibility with a wide torque range, including both inline 4-cylinder and V6 engines, while shortening development terms and minimizing investment. Additionally, it has superior packaging performance by optimizing the transmission size and arrangement achieving a low gravity center. It contributes to Vehicle’s attractiveness by improving driving performance and NVH. At the same time, it drastically improves fuel economy and quietness. Introduction Toyota Motor Corporation’s mid- to long-term product strategy to improve the competitiveness of its vehicle lineup is centered on the concept of building ever better cars. To help realize this concept, the Toyota New Global Architecture (TNGA) design philosophy was devised to achieve substantial improvements in product appeal while reducing costs. The new 8-speed UA80 is the first automatic transmission to be developed based on the TNGA design philosophy. The torque converter, gear train, valve body and oil pump of the transmission were commonized or optimized based on engine characteristics and required power performance. As a result, the UA80 transmission provides the optimum performance for the torque range of each engine, while shortening development terms and minimizing investment. The UA80 was developed in parallel with vehicle platforms, making possible to package the transmission to the best position and best shape considering the mounting system and driving performance.In addition, transmission efficiency was greatly increased by adopting many cutting edge technologies, such as widening the lock-up area, and incorporating a parallel-axis oil pump and low-friction clutch discs. Weight was substantially reduced by active substitution of materials, achieving class-leading fuel economy. Figure 1. UA80 cross section The optimum gearing was designed in consideration of the installation vehicle and engine characteristics, thereby greatly enhancing standing-start and acceleration performance. A new shifting control method was also adopted to achieve a powerful and Toyota New TNGA High-Efficiency Eight-Speed Automatic Transmission Direct Shift-8AT for FWD Vehicles2017-01-1093 Published 03/28/2017 Yosuke Michikoshi, Daisuke Kusamoto, Hirofumi Ota, Masashi Ikemura, and Noritaka Takebayashi Toyota Motor Corporation Ike Nobukazu, Yasuda Takashi, and Inoue Ryohei Aisin AW Co., Ltd. CITATION: Michikoshi, Y ., Kusamoto, D., Ota, H., Ikemura, M. et al., "Toyota New TNGA High-Efficiency Eight-Speed Automatic Transmission Direct Shift-8AT for FWD Vehicles," SAE Technical Paper 2017-01-1093, 2017, doi:10.4271/2017-01-1093. Copyright © 2017 SAE InternationalDownloaded from SAE International by Lund University, Tuesday, March 05, 2019direct acceleration feeling. This paper describes the major features, adopted techniques and performance of this transmission according to the below points. 1. Structure 2. Concepts and Features as a TNGA Unit 3. Fuel economy • Driving performance 4. Compactness • Lightness Structure Table 1 shows the UA80 main technical data. The UA80 consists of a front compound planetary, a rear Ravigneaux planetary, four clutches (C-1, C-2, C-3 and C-4) and two brakes (B-1 and B-2). Figure 2 shows gear train schematic. Table 1. Technical Data of UA80 Figure 2. Gear Train Schematic In general terms, in order to achieve additional multiple speeds, the number of components needs to be increased, as a result transmission size and cost are increased as well. The UA80 realized 8-speed gearing without increasing the number of components from a previous 6AT (6-speed automatic transmission). This greatly contributed to minimized transmission size, weight, and cost with an improved efficien