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Pennsylvania Railroad K4 class
Class of 425 American 4-6-2 locomotives / From Wikipedia, the free encyclopedia
The Pennsylvania Railroad (PRR) K4 4-6-2 "Pacific" (425 built 1914–1928, PRR Altoona, Baldwin) was its premier passenger-hauling steam locomotive from 1914 through the end of steam on the PRR in 1957.
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Pennsylvania Railroad K4 class | |||||||||||||||||||||||||||||||||||||||||||||||||||
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![]() PRR No. 3863 at Washington D.C. in the mid 1920s | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Attempts were made to replace the K4s, including the K5 and the T1 duplex locomotive. However, the low factor-of-adhesion of K5s meant that they were limited in their pulling power. By contrast, the T1s were very successful but suffered from greater maintenance costs, wheel slip due to poor springing, and inexperienced crews. The T1s also came too late in the game for steam traction. As such, the tried and tested K4s held their role as the PRR's primary express locomotives for thirty to forty years. The K4s hauled the vast majority of express passenger trains until they were replaced by diesel locomotives.
The K4s were not powerful enough for the heavier trains they often pulled from the mid-1930s onward so they were often double-headed or even triple-headed, sometimes with early Atlantics and E6s. This was effective but expensive, and several crews were needed. The PRR did have the locomotives needed for this, many having been displaced by electrification east of Harrisburg.
The two preserved K4s, Nos. 1361 and 3750, were designated as Pennsylvania's official state steam locomotives on December 18, 1987, when Pennsylvania Governor Robert P. Casey signed into law House Bill No. 1211.