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Toyota Four-Speed Automatic Transmission with Overdrive
A new four-speed automatic transmission with overdrive has been developed and put into production for the purpose of the improvement of fuel economy and the reduction of engine noise.
The transmission has the following characteristics:
Gear train arrangement having overdrive unit between the torque converter and the three-speed auxiliary transmission
High overdrive gear ratio
Shift feel controls for clutch-to-clutch shifting
Optimum shift points between third and overdrive gears on fuel economy, driveability and exhaust emissions
Lockout system of overdrive gear
This paper describes the design features and confirmation testings considered to assure the reliability and durability of the transmission.
It also refers to effects on fuel economy and noise of the transmission in the vehicle.
Numazawa, A., Kubo, S., Shindo, Y., and Moroto, S., "Toyota Four-Speed Automatic Transmission with Overdrive," SAE Technical Paper 780097, 1978,
Akio Numazawa, Seitoku Kubo, Yoshio Shindo, Shuzo Moroto
Toyota Motor Co., Ltd. (Japan)
1978 Automotive Engineering Congress and Exposition
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