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, AF40-6, AM6, AW6A-EL and TF-81SC. All-wheel drive transfer cases can be fitted to the AWTF-80 SC.
It uses a Lepelletier gear mechanism, an epicyclic/planetary gearset, which can provide more gear ratios with significantly fewer components. This means the Aisin AW TF-8# SC series is actually lighter than its five-speed predecessors.
The Ford 6R, GM 6L, and ZF 6HP transmissions are based on the same globally patented gearset concept. The AWTF-80 SC is the only one for transverse engine installation.
Key Data
Specifications
Combined Parallel and Serial Coupled Gearset Concept For More Gears And Improved Cost-Effectiveness
Main Objectives
The main objective in replacing the predecessor model was to improve vehicle fuel economy with extra speeds and a wider gear span to allow the engine speed level to be lowered. The layout brings the ability to shift in a non-sequential manner – going from gear 6 to gear 2 in extreme situations simply by changing one shift element.Extent
In order to increase the number of ratios, ZF has abandoned the conventional design method of limiting themselves to pure in-line epicyclic gearing and extended it to a combination with parallel epicyclic gearing. This was only possible thanks to computer-aided design and has resulted in a globally patent for this gearset concept. The AWTF-80 is based on the 6HP from ZF, which was the first transmission designed according to this new paradigm. After gaining additional gear ratios only with additional components, this time the number of components has to decrease while the number of ratios still increase. The progress is reflected in a much better ratio of the number of gears to the number of components used compared to existing layouts.Gearbox control
To reduce external wiring as well as to provide a constant environment for the transmission control module, 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.Gearset Concept: Layout
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 6 forward gears, and disengage it completely when at a standstill, significantly closing the fuel efficiency gap between automatic and manual transmissions.
Gearset Concept: Quality
The ratios of the 6 gears are evenly distributed in all versions. Exceptions are the large step from 1st to 2nd gear and the almost geometric steps from 3rd to 4th to 5th gear. They cannot be eliminated without affecting all other gears. As the large step is shifted due to the large span to a lower speed range than with conventional gearboxes, it is less significant. As the gear steps are smaller overall due to the additional gear, the geometric gear steps are still smaller than the corresponding gear steps of conventional gearboxes. Overall, therefore, the weaknesses are not overly significant. As the selected gearset concept saves up to 2 components compared to 5-speed transmissions, the advantages clearly outweigh the disadvantages.In a Lepelletier gearset, a conventional planetary gearset and a composite Ravigneaux gearset are combined to reduce both the size and weight as well as the manufacturing costs. Like all transmissions realized with Lepelletier transmissions, the 6L also dispenses with the use of the direct gear ratio and is thus one of the very few automatic transmission concepts without such a ratio.