Operating Dynamometer Car Ready to Run -- Union Pacific

Bigger, faster, heavier, better. As new steam locos made their way from the drawing boards to the ready track in the teens and 1920s, and older engines were modernized with new devices, railroads needed a way to accurately measure their performance. The answer was the Dynamometer Car, a specialized rolling railroad laboratory. Equipped with a large dynamometer to measure pulling power, other instruments were added as needed to measure a wide range of data while the engines were working in freight or passenger service. Armed with this information, company engineers provided detailed performance data that increased efficiency and lowered costs. Larger railroads often owned their own cars, and leased them to smaller lines as needed. Engine builders also had dynamometer cars as did some universities with railroad engineering programs. When diesels came, the cars were simply upgraded with the latest equipment and many were in service for decades; some are still in use today!