File:Pennsylvania Railroad - 1670 steam locomotive (0-6-0) 1 (26652635973).jpg

This is a coal-burning, class B6sb 0-6-0 steam locomotive on display at the Railroad Museum of Pennsylvania in the town of Strasburg. The engine was built in March 1916 at the Pennsylvania Railroad's Juniata Locomotive Shops.

Museum info.: "The heart of every railroad was its freight yards. Here, traffic from all points of the compass arrived, was sorted and reassembled into new trains, and dispatched across the system. Making all of this possible were switch engines. Scuttling back and forth, these little "yard goats" were kept busy day and night breaking down and making up new trains. Most never left the yard and rarely traveled faster than fifteen miles per hour, but their vital and demanding function made these tiny workhouses just as important to the railroad as any mainline locomotive.

The Pennsylvania Railroad spent decades perfecting the design of its yard switchers. First introduced in 1902, the B6 class was one of the most versatile and successful ever produced. The 0-6-0 wheel arrangement provided good traction by placing all of the locomotive's weight on the driving wheels. The sloped-back tender gave good visibility to the rear, important on a locomotive that would spend half of its career in reverse.

Beginning in 1916, the class was upgraded with the Pennsylvania Railroad's signature Belpaire firebox, superheaters and power reverse levers, and reclassified B6sb. These new additions made the B6sb units some of the most modern, powerful, and efficient 0-6-0s anywhere. Most of the class remained in service until diesels began appearing in the freight yards in large numbers in the 1940s. The last were not retired until the end of steam in 1957.

Built in 1916 for normal switching operations, No. 1670 was one of the first B class engines built new with superheaters, a Belpaire firebox, and a power reverse. It was common practice to exchange tenders between locomotives. No. 1670's tender was originally assigned to an older B6 on a Pennsylvania Railroad subsidiary, the Pittsburgh, Buffalo and Western, and was equipped with an oil tank in place of its coal bunker for some time.