Really excellent illustration of the reasoning and concepts behind the Prius drive system! Most importantly, he leaves out the planetary gear (power-split device) mechanism until the end, after he has motivated the need for it. A lot of other presentations of the Prius drive system start with the PSD, which just ends up confusing people because it’s a little hard to wrap your head around at first. It seems I’d seen an earlier version of this that doesn’t mention the gen-3 and -4 speed-reduction gear set. This version seems to have added a brief mention of it at the end.
The funny thing about a planetary gear box is that all conventional automatic transmissions have one in the back end of the transmission and that is the most reliable part of the transmission. It's no wonder it works so well in a Prius. Here is a question I have always wondered about. Can you call the Prius transaxle an automatic transmission? There are other designs of CVT transmissions that are a lot different than the Prius.
