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PRR 4-6-2 Locomotives (Class K-4s)


Last revised: March 11, 2024

By: Adam Burns

Perhaps the best-known 4-6-2's of all time was Pennsylvania Railroad's K-4s class. These steamers carried a simple beauty to it, which also lent to much of its success. 

However, beneath its good looks these 4-6-2s could also perform quite  exceptionally.. Another reason for the K-4s' popularity, at least among railfans and historians, was that fact that most were built the Pennsylvania's own Juanita shops, which built well over 300 in total with the remaining manufactured by Baldwin. 

It is important to point out, however, that the K-4s was not the only Pacific class the Pennsy owned; the railroad actually rostered over a half-dozen different types built over a 20-year span and virtually all (save for one) were listed as Class K. 

The K-4s is widely recognized today for its ruggedness and reliability; sporting PRR's noteworthy Belpaire fireboxes they could be found anywhere and everywhere on the railroad's massive system. 

The Pennsy was also one of the few roads to operate the wheel arrangement in freight service.  Generally, the Pacific type was a passenger locomotive but some roads did choose to expand its range. Today, two of the PRR's legendary 4-6-2s are preserved.


Pennsylvania 4-6-2 #1361 (K-4s) is seen here in commuter service on the New York & Long Branch at Red Bank, New Jersey, circa 1955. Fred Byerly photo. American-Rails.com collection.


By the turn of the 20th century many of the larger railroads realized that they were running into a problem; passenger trains were becoming larger and heavier as demand steadily increased which was resulting in multiple units needed to keep these expedited consists on a strict schedule. 

In 1902 the Chesapeake & Ohio was the first to put the 4-6-2 design into regular service for the very reasons mentioned above.   Somewhat surprisingly, it was not until 1906 that the Pennsylvania Railroad began looking at the possibility of utilizing such a locomotive for passenger operations. 

In 1907 the PRR collaborated with the American Locomotive Company's (Alco) Pittsburgh Works to build an experimental Pacific.  Interestingly, even here the railroad was still quite slow, deliberate, and calculated in its approach with the new locomotive. 

This first 4-6-2 was given road number 7067 and listed as Class K-28; it featured 80-inch drivers, a tractive effort of nearly 33,000 pounds, and weighed more than 208 tons (including tender). 

For an early Pacific design it was quite heavy in comparison to the C&O's examples (by more than 53 tons) with a tractive effort slightly better. This would be the only 4-6-2 of this class and it was later super-heated and designated as Class K-28s before being scrapped in 1933. 

In any event, the PRR was quite pleased with its trials and decided on the Pacific as its primary power for passenger service.

Pennsylvania Railroad 4-6-2 #3755 (K-4s) steams south over the Navesink River at Red Bank, New Jersey on subsidiary New York & Long Branch on November 10, 1950. Author's collection.

The K-4s was actually the fifth of six different classes of 4-6-2's the railroad owned following (by date) the K-28, K-2sa, K-21s/VK-1, K-29, and K3s. 

What would eventually become the PRR Class K-4s Pacifics 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-inch drivers, and Walschaerts valve gear, which blended just the right amount of power and speed to haul virtually anything the PRR asked of them. 

The PRR's designation for its K-4s was as follows: the "K" denoted the railroad's fleet of Pacifics while the "4" was simply the class number of the wheel arrangement; lastly, the "s" referred to the class being superheated.


Builder – Baldwin Locomotive Works, Alco, And PRR's Juanita Shops

Fuel - 16 tons

Whistle - PRR 3 Chime

Cylinders(2) - 27" x 28"

Water - 7,000 Gallons

Weight - 517,225 Pounds (Including Tender)

Diameter of Drivers – 80 Inches

Steam Pressure - 205 PSI

Tractive Effort – 44,460 Pounds

Pennsylvania 4-6-2 #830 (K-4s) is seen here working suburban service at Exchange Place Terminal in Jersey City, New Jersey during the 1950's. This was PRR's original station serving New York City, prior to the opening of Pennsylvania Station in downtown Manhattan (the skyline can be seen in the background, the tallest structure appears to be the Woolworth Building). This scene has changed drastically today; part of the facility is currently used by PATH's subway services but all signs of above-ground infrastructure are gone. Mac Owen collection.

The K-4s locomotives were first constructed between 1910 and 1911 and they proved so successful that while most of the railroad's 4-6-2s were retired by the 1930s they would soldier on until all steam was retired from the property in the late 1950s. 

Most of the 450 K-4s units were built directly by the railroad's own Juniata, Pennsylvania shop forces (375) while Baldwin also chipped in with 75 examples. 


The Pennsylvania Railroad used the company's own 3-chime whistle on its K-4 class of Pacifics.  This particular variant was also used on freight classes G5s (4-6-0), D16sb (4-4-0), J-1 (2-10-4), and M-1 (4-8-2).

Interestingly, while versatile and able to pull serious tonnage the K-4s was not Pennsy's most powerful Pacific, which was the K-5 built in 1929 that by far had the highest tractive effort, boiler pressure, and overall weight of any 4-6-2 the railroad operated. Despite their power, however, the K-5 was not considered successful on the PRR. 

Incredibly, while hundreds of 4-6-2s were put into service  just two survived the scrappers torch; #1361 currently at the Railroaders Memorial Museum in Altoona and #3750 at the Railroad Museum of Pennsylvania.   


First Restoration (1986-1987)

For years, #1361 sat as a moment at the railroad's fabled Horseshoe Curve in Pennsylvania after being retired by the railroad in 1957. In 1986 the locomotive was removed from its static display and restored to operational status to pull excursions. 

She pulled excursions from April, 1987 until 1989 when the locomotive was again sidelined after suffering a main bearing and drive axle failure.

The locomotive was slated for a quick rebuild and return to service.  However, a lack of leadership and direction on the project saw its completion continually pushed back.

This drove up costs and after more than a decade of work the restoration had cost $1.7 million with no timeline on completion.  In 1996 she had been disassembled and moved to the Steamtown National Historic Site in Scranton, Pennsylvania.

Here she sat as Altoona, Steamtown, and the University of Scranton teamed up on the project.  Finally, with no end in sight, Altoona stopped funding in 2007 and the locomotive was returned to the museum.

Afterwards, the Pacific returned to public display; here she sat for more than 20 years.  It is a funny thing how things come full circle.

203952093472374276357268309784.jpgPennsylvania 4-6-2 #612 (K-4sa) leads a farewell-to-steam fan trip between Sea Girt and Jamestown, New Jersey on October 20, 1957. American-Rails.com collection.

Current Restoration and Status

Beginning in the late 2000's and continuing through the 2010's, a great resurgence in steam locomotives began.

During this time multiple restorations were launched; some have been completed while others are still underway.  Notables here include:

  • Norfolk & Western 4-8-4 #611

  • Reading 4-8-4 #2100

  • Nashville, Chattanooga & St. Louis 4-8-4 #576

  • Reading 4-8-4 #2102

  • Chesapeake & Ohio 2-8-4 #2716

  • Union Pacific 4-8-8-4 "Big Boy" #4014

It appears many of these restorations are spurred both by the public's appetite to see these machines in action and train enthusiasts' interest in bringing a piece of history back to life.

The restoration of K-4 #1361, announced on June 24, 2021, is thanks to a new vision at the Railroaders Memorial Museum, led by renowned preservationist and former Norfolk Southern chariman/CEO C. Wick Moorman

He is currently the museum's Chairman of the Board and is also helping oversee the restoration of the nearby East Broad Top Railroad.

His vision and leadership at Altoona spurred the current restoration of #1361 which now has a group of dedicated professionals working on the project.

The locomotive's restoration is expected to cost $2.7 million although a final completion date has yet to be announced.  To learn more please click here.


Wes Barris's SteamLocomotive.com is simply the best web resource on the study of steam locomotives. 

It is difficult to truly articulate just how much material can be found at this website. 

It is quite staggering and a must visit!