Class C designated Pacifics of the Maine Central for passenger service, which were significantly lighter than the later USRA Light Pacific. The actual C from 1907 was delivered without a superheater. The C1 and C2, built from 1912 onwards, were operated with superheated steam from the start. After 16 locomotives from the first series, five C-3s were built in 1917, which had significantly larger cylinders with a lower boiler pressure. 