vintage brass educational electric motor or dynamo
 

I have what appears to be an educational motor or dynamo. The base and
end pieces are cast brass. The end pieces have needle bearings to
support the shaft. There is an armature (with no wire in it at this
time), but instead of the commutator there are two brass rings with
many holes which I presume is where you can bolt different
kinds/sizes/number of commutator pieces to experiment. The only
identification is the letters "E & V" cast under the base, along with
some numbers that look like parts numbers. No tag, no model numbers,
etc. Does anyone have any information on this item?