MTH - Premier Steam Locomotives - 4-6-6-4 Challenger - O Scale 3 Rail - (Hi-Rail Wheels)

The first Challengers were conceived in 1936 as fast freight engines to replace the Union Pacific's fleet of three-cylinder 4-12-2 locomotives. With an extra center cylinder for added power and a top speed of 45 mph, the 4-12-2s had been successful freight engines when built in 1926. But a decade later they were considered slow and difficult to maintain. So American Locomotive Works (Alco) was commissioned to build what became one of the most successful fleets of articulated engines on any railroad. Forty Challengers were built in the 1930s. The pressure of wartime traffic brought an order for 65 more with bigger tenders and many minor improvements.