AWTF-80 SC

The Aisin AW TF-8# SC series is a 6-speed automatic transmission designed for use in transverse engine applications produced by Aisin Seiki. It is built in Anjō, Japan, and is also called TF-80SC (AWF21), AF40-6, AM6, AW6A-EL and TF-81SC (AF21). All-wheel drive transfer cases can be fitted to the AWTF-80 SC.

Basic concept
A conventional 5-pinion planetary gearset and a compound Ravigneaux gearset is combined in a Lepelletier gear mechanism, to reduce both the size and weight. It was first realized in 2000 with the 6HP from ZF Friedrichshafen. Like all transmissions realized with Lepelletier transmissions, the AWTF-80 SC also dispenses with the use of the direct gear ratio, making it one of the very few automatic transmission concepts without such a ratio.

It also has the capability to achieve torque converter lock-up on all six forward gears, and disengage it completely when at a standstill, significantly closing the fuel efficiency gap between automatic and manual transmissions.

Gearbox control
To reduce external wiring as well as to provide a constant environment for the transmission control module (TCM), it is located inside the transmission housing. Gear shifting is managed by a computer program that oversees a clutch-to-clutch actuation that allows one clutch engage the instant the clutch from the previous gear disengages. When idling and with the foot brake depressed neutral gear is selected automatically. This helps to reduce internal temperatures and improve the fuel economy.