Abstract: A U-shaped subslot liner is disposed in the bottom of a slot in the rotor of a dynamoelectric machine. A stack of conductors and insulating layers is supported by arms of the subslot liner durig manufacture. The subslot liner, together with the lower conductor, defines a coolant channel for conveying a gaseous coolant to the conductors. A slot armor lines the sides of the slots where it is retained against centrifugal acceleration by the subslot liner. In one embodiment, the slot armor passes completely under the subslot liner. In other embodiments, the slot armor is in two pieces, each affixed to the subslot liner.