Yes, the Altorfer Brothers did invent the concentric action in their machines. ABC sold out to Kelvinator in the mid or so 50's. American Motors owned Kelvinator, so since they bought out ABC, I would think that they could do what they liked?
I have an older ABC wringer machine and it says Peoria, Il. on it for the place of manufacture. I have another ABC wringer machine which is a bit newer and it says ABC on the front of the machine but the tag says, made my Kelvinator, a product of American Motors Detroit, Michigan.
It will be interesting to see if anyone else gives some information on this. Gary