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240 Landmarks TopTransmission and Drive Train > Electronically-controlled 4-speed AT
 Electronically-controlled 4-speed AT
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This, the world's first 4-speed AT with overdrive (A43L), was developed in 1977. It had an overdrive mechanism located between the torque converter and 3-speed auxiliary transmission. It was followed in August 1981 by the world's first full-scale microcomputer controlled 4-speed AT with overdrive (A43DE). This AT used microcomputers in its control portion and an electronic controlled transmission (ECT) system. It was introduced in the Crown 2800 Royal Saloon as a world first, for the purpose of improving fuel efficiency and drivability. This system judged various conditions using the microcomputers to perform speed changes and lockup operations precisely with hydraulic control. Taking advantage of the microcomputer control, users could select three shift patterns (Normal, Power, and Economy) through a mode select switch that set the lockup range. The ECT had three main features.
(1) Precise control of the lockup torque converter and shift points (lockup operation from the 2nd low speed, etc.) greatly improved fuel efficiency (approx. 10% improvement over a conventional 2-way overdrive 4-speed AT).
(2) The easiest shift pattern could be selected depending on the driver's preference and road conditions.
(3) Based on signals from various sensors, shift point and lockup clutch operations were precisely controlled to improve the shift characteristics and drivability.
The ECT introduced in the Crown created a sensation, and similar systems were later introduced in popular cars, verifying the advantage of electronic control.
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Storage location:AISIN AW CO., LTD., TECHNICAL ADMINISTRATION DEPT. (10 Takane, Fujii-cho, Anjo-shi, Aichi-ken 444-1192)
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Year manufactured:1981
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Manufacturer:Aisin AW Co., Ltd.
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Classification:Mass-production part
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Current status:On display (static)
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Name / Manufacture
Model name:E-MS112
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Company name:Toyota Motor Corporation, Aisin AW Co., Ltd.
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Applied model:Toyota Crown Royal Saloon
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Year of manufacture:1981
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Specification
Shift / operation method:Electronically controlled planetary gear type (Simpson type planetary gear (3-speed) + overdrive mechanism)
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Transmission type:Torque converter
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Speeds:Three-member one-stage two-phase type (with lockup mechanism)
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Gear ratio (forward):1st speed: 2.452, 2nd speed: 1.452, 3rd speed: 1.000, 4th speed: 0.688
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Gear ratio (reverse):2.212
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Potency
Effect:Fuel consumption ratio: 10 mode 8.1km/L, 60 km constant speed running 15 km/L
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Points of interest, topicality:The world's first ECT using microcomputer control. Later, similar systems were introduced in popular cars.
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Features:This system judged various conditions using microcomputers to perform speed changes and lockup operations precisely with hydraulic control. Users could select three shift patterns (Normal, Power, and Economy) that set the lockup range.
(1) Precise control of the lockup torque converter and shift points (lockup operation from the 2nd low speed, etc.) greatly improved fuel efficiency (approx. 10% improvement over a conventional 2-way overdrive 4-speed AT).
(2) The easiest shift pattern could be selected depending on the driver's preference and road conditions.
(3) Based on signals from various sensors, shift point and lockup clutch operations were precisely controlled to improve the shift characteristics and drivability.
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