I came across YouTube videos from Weber State University showing the history and operation of the transmission in the Fusion and C-max hybrid.
In the 2005 Escape hybrid, Ford used a transmission from Aisin. Aisin appears to be a Toyota controlled transmission supplier to Toyota and other auto makers. Ford used two generations of Aisin transmissions in the Escape hybrid 2005 through 2012. Then in 2012 Ford began producing the HF-35 in our cars.
As the first video shows, there is essentially no difference between the HF-35 and the earlier Aisin transmissions used in the Escape:
The instructor goes through the opened transmissions in order and reaches the HF-35 around minute 12, as I remember. Apparently a version of this transmission is also used in the Chrysler Pacifica hybrid, as well as in the latest generation of the Prius (earlier Toyota used a related design, but just recently moved to this more compact design with MG1 and MG2 in parallel that Aisin developed for Ford).
This second video covers the electrical control system of the HF-35:
All in all, these transmissions, even with the motor / generators, look to be somewhat simpler than the complicated hydraulic automatic transmissions of the past. The magic is in the electronic control systems.
One point he mentions in second vid is that the oil pump for the transmission is driven by the engine shaft. So, as I understood him, on the C-max hybrid there is no oil flow in the transmission when the vehicle is running in EV mode, engine off. Whereas the Energi version of the transmission adds an external electric oil pump to lubricate the tranny when the engine is off. This suggests that in similar service the Energi transmission might have a longer life than the regular hybrid version.
Edited by djc, 21 January 2019 - 04:18 PM.