It’s whats called a Schrage motor. The windings are in the rotor, not the stator, fed by slip rings. Then there is a second set of windings fed by the extra brushes that are used (as I understand it) to control torque by controlling the relative phase angles between them. The brushes move mechanically via a control wheel next to the motor. It’s kind of like a wound rotor motor than doesn’t need external resistors.
I’ve heard/read of them and a friend in Sweden has talked about them but I’ve never actually seen one. I don’t think anyone uses them here in North America, at least not anywhere in any of the plants I have worked in or on. So thanks for the “motor porn” Tony!