Great Northern Railway Y-1 class electric locomotive, depicted in Washington state

A Y-1 class electric lovommotive has the Glacier Park Limited in tow on what is today the Iron Goat Trail in Washington's Cascade Mountains. (From the January 1950 cover of Railroad magazine)

The Y-1 was a 1-Co+Co-1 type of which 8 were built between 1927 and 1930 at Schenectady, New York, with car bodies manufactured by American Locomotive Company and electrical components supplied by General Electric. They used motor-generator sets to rectify the 11 kV 25 Hz alternating current line voltage into direct current for their traction motors -- 3,000 horsepower (2.2 MW).

The Great Northern numbered the units 5010–5017. After being involved in a wreck at Tonga, Washington in July 1945, the 5011 was rebuilt with a streamlined appearance and EMD F-unit cabs; the GN reclassified it as Y-1a.

In 1956, the GN dieselized operations through the Cascade Tunnel. The electrical system was decommissioned, and the Y-1 locomotives were sold to the Pennsylvania Railroad, who classified them as FF2. GN 5011 was broken up for spares, and the remaining seven locomotives were overhauled and converted to PRR standards and then placed into service, being assigned numbers 1–7 on the PRR. They lasted a few more years on the PRR, and were all scrapped between 1957 and 1966.

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