When the Portland Shops started building new motors from scratch, the Port of Montreal asked if they could produce some new units to supplement/replace their increasingly elderly collection of English Electric motors. Management didn’t see any reason not to, so a little subsidiary was formed to market steeplecab switchers to the remaining DC electrifications in North America.

The resulting unit was the Portland SW; a 100 ton 3000 HP steeplecab set on a pair of class E trucks. The PdM’s units were delivered in March of ‘67, then the New York Central ordered three of them, which were delivered in December (to become Penn Central 4740-4743 in 1968), but, alas, no other railroad was at all interested in expanding their electrifications.

Seven SWs were built; 4 for the PdM & 3 for the NYC. The PdM units are still in operation, but the NYC units were retired and scrapped in the late 1990s.