Thursday, July 20, 2017

Keeping cool

The Museum's primary locomotives are Baldwin-built RS4-TC switchers built for the Army Transportation Corp and the Air Force in 1953.  Their original cooling systems consisted of a large radiator cooled with a fan driven directly from the prime mover, a V12 Caterpillar D197. In the early 1950s this was a typical design used by nearly all locomotive manufacturers.

Beginning two years ago, following a problem with the mechanical drives, the cooling systems were altered with the addition of six electrically-driven fans.  The mechanical fan drive was disconnected from the prime mover and abandoned in place.  

The electric fans were in theory a brilliant solution to an expensive problem.  And they are of high quality intended for use in Kenworth and other large trucks. (Kenworth trucks are built by PACCAR who until 1983 produced legions of freight cars and cabooses.)  However, after two years, shop forces discovered the fans are susceptible to water running down the drive shaft and corroding the electric motor bearings.  When used as originally intended, the fans are not directly exposed to rain because they are located under a hood.  So a modification has been implemented that flips the fan upside down, reverses the motors, and mounts the fan blades upside down.  So far, the system is performing well, but a fall and winter will be required to fully test the alteration.

This is another example of the many small behind-the-scenes projects that keeps the Northwest Railway Museum railway operating.  Consider taking the grand tour on the first Saturday of August to learn more about the workings in the Conservation and Restoration Center!

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