That enduring legacy is bestowed on the PRR class K4s, 4-6-2 locomotive. The K4s was born out of extreme necessity in 1914, when the PRR belatedly confirmed that they had to break with their limiting phobia about adding one extra set of drive wheels to passenger locomotives. Until that time, management steadfastly believed larger 4-4-0 or 4-4-2 locomotives represented maximum efficiency in motive power. To prove the point, PRR built the famous E6s 4-4-2 locomotive that was designed to out perform the standard 4-6-2 locomotives of that era.  The E6s could easily move 14-car passenger trains at speed on level mainline, but was challenged on many parts of the PRR mountain-grade mainline in the state of Pennsylvania and elsewhere.

The first K4s (the “s” designated that the locomotive was equipped with a superheater) locomotive #1737 emerged from the PRR Juniata Shops in 1914. The design was not a completely in-house creation since many of the specifications of #1737 were copied from a one-of-a-kind, experimental 4-6-2 locomotive that was class K-29 built by American Locomotive Company in October of 1911 – that PRR purchased as an iron horse “trail balloon”. The K4s was among the largest 4-6-2 locomotives in that era and proved to be successful in service. Still, PRR had difficulty with committing to mass-production. The dramatic surge in rail traffic on the eve of World War I finally forced PRR’s hand when they placed orders for 41 in 1917 followed by another 111 in 1918.

When peacetime resumed, PRR adopted the posture that the K4s was “all they needed” despite the increasing practice of double-heading locomotives that continually increased in size correspondingly, products of the travel surge of prosperous economic environment in the late 1920s. That insular perspective saw the PRR placing orders for the last 100 K4s locomotives in 1927 and 1928 – arguably when they should have looked at dual-service 4-8-2 locomotives or the popular 4-6-4 Hudson class other railroads were embracing. At that point, PRR fielded 425 class K4s locomotives.

Focus on mainline electrification between 1929 and 1939 effectively ended any structured look at modern steam power and that void placed the PRR behind many of its competitors. Interest in modern steam locomotives resurfaced in 1940 when management became interested in the polar opposite of the conventional steam locomotive designs and invested $40 million dollars in a fleet of controversial duplex-drive steam locomotives that failed to perform. After 1945, the balance of the PRR motive power history would be written by diesel-electric and electric locomotives.

Problems aside, due to its wide spread application and handsome appearance, the K4s was the locomotive most associate with the grand years of the PRR. That commanding image was not lost on artists and photographers and dynamic images of the K4s powering PRR passenger trains dominated transportation advertising in the 1920s and 1930s. When streamlining became vogue in the mid-1930s, noted industrial designer Raymond Loewy fitted K4s #3768 with an aerodynamic shell -nicknamed the Torpedo – but crews complained that the shell concealed many of the vital parts of the locomotive that needed frequent maintenance. In 1940 PRR corrected that problem with streamlined K4s locomotives #1120, #2665, # 3678 and #5338 – all featured a design that left the “eccentrics” of the locomotive open to facilitate maintenance. Those four locomotives were normally assigned to the Trail Blazer and Jeffersonian, all-coach trains west of Pittsburgh. In the end, class E-7 and E-8 passenger diesels acquired in 1945-1952 gradually replaced the K4s on most mainline trains and by 1956, only 72 remained active.

Some facts about the fleet: the first K4s locomotive scrapped was #8309 – badly damaged beyond repair in 1938; K4s #612 was the last of the class to power a fan trip on October 20, 1957; locomotive #5351 was the last K4s used to power a scheduled passenger train in November 1957: the first K4s #1737 was set aside for preservation in 1956 but by 1960 it had deteriorated to the point it was scrapped – but PRR renumbered #3750 to represent #1737 and finally the PRR donated #1361 to the City of Altoona for display on Horseshoe Curve. Only two K4s remain: #1361 (being restored for mainline excursion service) and #3750 –with its correct road number restored – as a static display.

For all those reasons we would like to call your attention to the K4s locomotives we now offer in both conventional, fleet appearance and with streamlining – in several scales. These locomotives are the ideal size for most model railroads and remain captivating examples of the age of steam on the PRR.

Frank Wrabel

modeltrainstuff.com