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Delaware & Hudson 4-6-6-4 Locomotives (Class J)

Published: February 12, 2024

By: Adam Burns

Delaware & Hudson's 4-6-6-4s were a series of simple articulated locomotives designed for freight service as the railroad sought greater overhead bridge traffic 

Built by the American Locomotive Company, the beautiful engines were known for their power and efficiency, and used extensively in handling fast freights although the D&H network.

Unfortunately, the big Challengers saw only a decade of service before their retirement came due to newly arriving diesels, predominanetly in the form of RS2s and RS3s.  

The diesels were not as powerful but could be utilized in a range of different applications, from main line work to branch duties.  This greater redundancy no doubt led to Challengers' quick retirement by the early 1950s.  Alas, none of these fine machines were preserved.  


2897352863582367236827868927.jpgOne of the Delaware & Hudson's big 4-6-6-4s (J), #1500, is seen here in Mechanicville, New York on what appears to be a caboose hop during July, 1948. Despite its small size, the D&H owned many "Challengers" (40), acquired between 1940-1946. All were scrapped by August, 1953.

Bridge Traffic

The Delaware and Hudson Railway (D&H) was a prominent rail system that emerged in the nineteenth century, and its fleet of 4-6-6-4 steam locomotives carried significant weight in the history of American railroading.

These locomotives, colloquially known as "Challengers," were designed to move heavy freights at high speed across the railroad's sprawling railway network.

In his book, "Delaware & Hudson: The Bridge Line to New England and Canada," author Jim Shaughnessy notes the railroad's long-profitable anthracite coal business was drying up by the 1930s.

The rock had been used for decades heating residential and commercial buildings thanks to its clean burning properties.  However, with the rise in electricity and oil-fed furnances railroads which had relied on anthracite - names like the D&H, Lackawanna, Lehigh & New England, Lehigh Valley, and others - were forced to find other freight to offset this declining business.

Joseph Nuelle, elected president of the D&H on May 16, 1938, was tasked with doing just that.  His answer involved greatly increasing the railroad's bridge traffic between Canada and New England, especially its connection with the Boston & Maine at Mechanicville, New York.

To do this involved faster and more powerful steam locomotives.  The company's reliable but aging fleets of 2-8-0s were simply not able to handle heavy freights at high speed.

As a result, Nuell placed an order for 20 new 4-6-6-4s from American Locomotive in 1940.  The D&H's Challengers were mammoth machines, which have also been described as one of the most beautiful large articulated designs ever built.

Known officially as Class J, the locomotives were D&H's most imposing and versatile locomotives. They boasted clean lines with a sleek, smooth boiler, white trim, white-wall wheels, short pilot, and centered bell on the smokebox.  The company was so-proud of these engines, #1501 was placed on public display at Albany, New York following its delivery.

This initial roster, #1500-1519, had cost $178,900 each for a total price tag of $3,578,000.  The engines were fine machines and lived up to their billing; they could either hustle fast freights at speeds of 50 mph or work helper assignments on the Penn Division. 


Nuelle's efforts proved a resounding success as the D&H's interchange traffic at Mechanicville increased by 43.7% between 1940-1941.  In addition, similar business at Rouses Point, New York jumped by a staggering 263.8% during the same period.

The great influx of freight traffic - which increased once the U.S. became involved in the global conflict - convinced Nuelle to order 15 more Challengers from Alco in 1942.  The price of this group increased to $213,500 per locomotive. 


Each engine, with its accompanying tender, weighed a staggering 987,00 pounds. They were equipped with roller bearings on all axles, including the rods to lower the maintenance needs and facilitate smoother operation. The boiler pressure was adjusted to 265 pounds per square inch, driving the 69-inch wheels at a starting tractive effort of 94,000 lbs.

These locomotives came with a large tender capable of carrying 22,500 gallons of water and 26 tons of coal. They were geared for 60-70 mph operation and it is said these Challengers were the most stable, and smoothest riding, big articulateds ever built. The Class Js, despite their imposing size and power, were lauded for their speed, flexibility, and reliability.

Final Years

Interestingly, despite recognizing the diesel's potential, the D&H continued ordering more Challengers through the mid-1940s.  Between 1945-1946 it acquired its last final five, #1535-1539, at a cost of $1,125,000.

The final engine, #1539, was noteworthy as featuring a welded boiler, a design pioneered by the D&H itself on 2-8-0 #1219 in 1937.  Despite their illustrious performance, the Challengers' service life was quite short due to the advent of diesel-electric technology.

The D&H purchased its first 1,500 RS2s for general road service in 1946, acquiring more RS2s throughout that decade, and RS3s through the 1950s.

By then, diesels were universally accepted by both the D&H - and the industry in general - as the more cost-effective and efficient locomotive.  As a consequence, the fleet of 4-6-6-4s, like other steam giants, was gradually phased out.

Between 1952-1953, all of the Class Js were retired, bringing an end to the age of steam glory on the D&H system.  Incredibly, the last five enjoyed only a few years of service before they were scrapped!

Data Sheet

Delaware & Hudson
Wheel Arrangement
American Locomotive Company - Schenectady Works
Road Numbers
Completion Date
1940 (1500-1519), 1943 (1520-1534), 1945 (1535-1538), 1946 (1539)
Engine Wheelbase
59' 11 1/32"
Tender Wheelbase
Overall Wheelbase
103' 6"
Cylinders: Diameter & Stroke (High Pressure)
20 ½" x 32"
Valve Gear
Weight on Drivers
406,500 Lbs
Axle Loading
Engine Weight
597,000 Lbs
Tender Weight
390,180 Lbs
Total Engine and Tender Weight
987,180 Lbs
Tender Capacity
22,500 Gallons/26 Tons (Coal)
Diameter of Drivers
69 Inches
Steam Pressure
285 psi
Tractive Effort
94,428 Lbs
Factor of Adhesion
Evaporative Heating Surface (square feet)
Grate Area (square feet)


Today, while none of D&H's 4-6-6-4s survive, two similar locomotives from the Union Pacific are extant; #3985 and #3977, providing a tangible example of this colossal wheel arrangement.

Likewise, the memory and significance of D&H's Challengers live on through historical documentation, photographs, and the indomitable spirit of rail enthusiasts and historians worldwide.

In the annals of the Delaware & Hudson, the 4-6-6-4 Challengers hold a special place. They were not just engines but monumental innovations symbolizing an age of unfettered industrial progress and engineering prowess.

Their legacy remains a testament to the prime of American railroading, serving as an enduring symbol of a time when steam giants ruled the rails.


  • Morrison, Tom. American Steam Locomotive In The Twentieth Century. Jefferson: McFarland & Company, Inc., 2019.
  • Shaughnessy, Jim.  Delaware & Hudson: The Bridge Line To New England And Canada.  Syracuse:  Syracuse University Press, 1997 edition.
  • Simpson, Walter. Steam Locomotive Energy Story, The.  New York: American University Presses, 2021.

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