The Model A generator was a 5 brush unit, the shape resembling that of the generators used in large hydro-electric plant powerhouses, thus it is commonly referred to as a powerhouse generator. About October 1928 the powerhouse changed to a 3 brush unit, and about this same time the Autolite style generator was introduced, but not commonly installed until near the middle of 1929.
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Model A Generators Pt 1 Oct 2012