The Pennsylvania Railroad Class K-4 Pacific

Perhaps the best-known steam locomotive of all time was the Pennsylvania Railroad Class K-4 Pacific. This steamer carried a simple beauty to it, which also lent to much of its success. Another reason the K-4 is so popular is because almost all of the locomotives were built directly by the PRR itself in its famous Juanita shops, well over 300 in total with the remaining being built by Baldwin. Perhaps what made the locomotive so successful was the perfect blend of weight, size and powerful that allowed it to haul almost anything from passenger to heavy freight trains.

The Class K-4 Pacific is undoubtedly the most popular Pacific design ever built. In all the Pennsylvania Railroad would come to own 424 of these masterfully crafted machines (the Juniata shops built 349 of the locomotives with the Baldwin Locomotive Works chipping in another 75) and they would carry everything from freight to the railroad’s most well-known passenger trains.

What would eventually become the Class K-4 Pacific resulted from an earlier Class E-6 Atlantic design, incorporating the 4-4-2 wheel arrangement, and the American Locomotive Company’s K-29 Pacific design. Mechanically the most famous features of the K-4s would be their Belpaire fireboxes, 80” drivers, and Walschaerts valve gear, which blended just the right amount of power and speed to haul virtually anything the PRR asked of them.

Builder – Baldwin Locomotive Works and the Pennsylvania Railroad

Fuel - 16 tons

Cylinders(2) - 27" x 28"

Water - 7,000 Gallons

Weight - 468,000 Pounds

Diameter of Drivers – 80 Inches

Steam Pressure - 205 PSI

Tractive Effort – 44,460 Pounds

The K-4s were first constructed between 1910 and 1911 and they proved to be so successful that while most of their sisters of the Pacific class were retired by the 1930s they would soldier on until nearly the end when diesels began to replace all steam locomotives. The locomotive would virtually become the face of the Pennsylvania, even after the entire fleet was retired.

It should be noted that at least one Class K-4 Pacific is to see active service once again; K-4 #1361 is under restoration by the Horseshoe Curve Chapter of the NRHS although its restoration is now on hold due to high costs.

Also, consider the book American Steam Locomotives from author Brian Solomon. While this publication does not include quite as much technical data as Parker's book, How a Steam Locomotive Works, it is still a very good resource with lots of information covering many of the most popular steam designs such as Pacifics, Ten Wheelers, Berkshires, and Hudsons and best of all, is loaded with photographs! If you're interested in perhaps purchasing either (or both) of these books please visit the links below which will take you to ordering information through Amazon.com, the trusted online shopping network.