B73 is completely a product of the Keystone State. Its car body and mechanical parts were built by Baldwin at Eddystone, near Philadelphia. The unfinished body was shipped on its own wheels to Westinghouse’s East Pittsburgh works, where final assembly took place. Its electrical equipment was also was produced at East Pittsburgh while its Westinghouse diesel engine was manufactured in that firm’s South Philadelphia works.

When completed in July 1930, the locomotive weighed 78 tons and was rated at 400 horsepower. It was originally sold to the American Steel & Wire Division of United States Steel and served the Cuyahoga Works as their #1 until displaced by larger diesels in 1942. Following an overhaul by Westinghouse, it became B73 at American Rolling Mills Co. in Butler, Pa. ARMCO replaced the original engine with a later model 400 HP Hamilton engine in 1947. Newer and larger diesels again sidelined B73 in 1965 and in 1970, ARMCO donated the unit to the museum after generously rebuilding the trucks with new wheels.

A close inspection of B73 reveals its similarity to MWP 3000. Diesels are little more than electric locomotives that carry their own power plant, and both units have many similar components. B73 remains in operating condition and is used occasionally to shift our standard gauge rolling stock. It can also be used to power the trolleys during long outages.