The Pennsylvania Railroad K4 was a class of 425 4-6-2 steam locomotives built between 1914 and 1928 for the Pennsylvania Railroad (PRR), where they served as the primary mainline passenger steam locomotives on the entire PRR system until late 1957. Attempts were made to replace the K4s, including the K5 and the T1 duplex locomotive.

Here is a steam locomotive portrait of Pennsylvania Railroad engine #5399, a K-4S (4-6-2) "Pacific" built in Juniata during August of 1924, rebuilt with Poppet Valves and a front-end throttle in 1939, and retired in November of 1953 after 29 years of faithful service.

2012年3月10日 · This K4 single handled trains normally hauled by double headed K4s. The modifications made to the 5399 was assisted by a front end arrangement to lessen pressure and temperature drop of steam between the boiler and cylinders. The 5399 received a larger dry pipe, front end throttle and larger steam and exhaust pipes.

2020年9月14日 · 5399 was fitted with Franklin Type A valve gear. This conversion is dealt with in detail in Vernon L Smith’s “One Man’s Locomotives”. The conversion to a front end throttle was part of a conversion to increase the steam flow area right through from the boiler to match the capability of the poppet valves.

Notes for class K4: all were built with 27" x 28" cylinders, 80" drivers, cast Kiesel trailing trucks, Belpaire fireboxes with 69.9 square feet of grate area, piston valves and Walschaerts valve gear.

Another experimental member of Pennsylvania Railroad's K-4s class, No. 5399, poses in Chicago on December 14, 1947. She has the repositioned headlight and turbogenerator applied to many of the K-4s class in later years, though not the solid steel pilot.

1. Was this conversion by Lima in 1939 the only one? 2. Were others modernized by PRR itself. 3. How does a front-end throttle improve performance?

The k4 tests were made in 1939 and reported in Railway Mechanical Engineer as attached. In the cylinder detail it surely appears to have been cast. I was half expecting that it would have been a weldment, a la' some of the M cylinders, as seen in the Hagley pix

Among the many photos I found a pic of K4s 5399( pg. 232). A little reserch found that it was rebuilt by Lima (!) with popet valves operated by osalating(sp) cams and " other modefications" but not what they were.

Up for auction is a Brass HO NJ Custom Brass PRR K-4s No. 5399 4-6-2 Locomotive No. 856. This model was made in Korea by Daiyoung Models. Overall very nice detail, including nice in-cab detail.