New York Central 4-8-4 "Northern" Locomotives in the USA

Class S-1A/S-1B

The New York Central was in need of more motive power to handle its increasing passenger business in the years right after World War II. NYC's Paul Kiefer, Chief Mechanical Engineer of Motive Power and Rolling Stock wanted a new locomotive with a larger boiler capacity, more adhesive weight and greater tractive effort than the 4-6-4 Hudsons and more stamina than their recently built L-4 Class 4-8-2's.

The answer was a 4-8-4 with 30% more tractive effort and 25% more grate area, a 6000 HP rating, and roller bearings on all axles, coupling rods and connecting rods.

The American Locomotive Company was given the order. So confident of the design was the New York Central that before the prototype could be delivered, an additional order for 26 similar locomotives was again placed with Alco for delivery in late 1945 and early 1946, all with 79" drivers instead of the 75" drivers of that initial S-1A. Alco delivered that first Class S-1A 4-8-4 in 1945. In keeping with the design goal of 6000 HP, this new locomotive was given road number 6000.

Class S-2A

In 1946, The American Locomotive Company delivered the 26 locomotives of the second order. 25 of these were designated Class S-1B Niagaras. The 26th locomotive was an experimental unit with Franklin-Caprotti poppet valves instead of Baker valve gear and piston valves. Poppit valves operated much like the valves in an internal combustion engine. It carried number 5500 and was designated Class S-2A.

In tests, number 5500 quickly proved to be a "Super Niagara". The 4-8-4 was not only more powerful than the rest of the fleet, but was also more economical, burning 15% less fuel per horsepower than a piston valve sister. Testing continued for several years after delivery, and it is entirely possible that the S-1A and S-1B classes would have been converted to poppet valves had steam locomotive development continued. After testing, number 5500 was assigned to the same duties as the best of the 4-8-4's which included fast freight and premier passenger assignments. With its poppet valves, 5500 presented some unique maintenance problems. Considered an orphan, it was decided to retire 5500 in 1951 after a career of only 5 years. After retirement, 5500 was used as a "hanger queen", supplying parts to the rest of the 4-8-4 fleet. The remains of 5500 were sold for scrap in 1956.


The indicated (i.e. cylinder) HP of the Niagaras were 6680 at 85 mph. The maximum drawbar HP was 5070 for the S-1B at 62.5 mph (Niagara #6023 was tested). The complete dynomometer test report from this over-the-road testing, which was conducted per industry standards, and contains this documentation, is available from the New York Central System Historical society.

The NYC had 4-8-2's called "Mohawks" named after a river and 4-6-4's called "Hudsons" named after another river. It completed its passenger motive fleet with the new 4-8-4s which it called "Niagaras" after a third New York river.

On delivery, the S-1B fleet was immediately placed into service on the NYC's premier trains, including the 20th Century Limited, the Empire State Express, the Chicagoan, and the Commodore Vanderbilt over the four track main between Harmon, New York and Chicago. The 4-8-4's were capable of almost any preferred assignment, and exceeded all design expectations. The Niagara's were also used in fast freight service, such as the famed Pacemaker trains, when they could be spared from the "Great Steel Fleet". It was discovered that the huge boiler could generate steam faster than it could be used by the machinery. The experimental S-2A, with its poppet valves in the cylinders (operating much like the valves in an automobile engine) proved even more efficient and if steam development had continued, the S-1A and S-1B's would probably have received this improvement.

Other modern 4-8-4's may have exceeded the S-1B's in the categories of weight and tractive effort but it is doubtful that any exceeded this ultimate example of locomotive building in terms of steam generation, horsepower, speed and ability. A new boiler design eliminated the steam dome and allowed the boiler size to be increased to the very limits of the NYC loading gauge. The boiler was so large that the sandbox had to be recessed into the boiler top and the stack was unusually short. The air reservoirs were cast into the massive frame, the turbo generator had to be located below the enormous firebox and the bell was located on the pilot beam. The standard NYC appearance was altered with the use of an unusual smoke box front and a headlight placed above the boiler center line. These new 4-8-4's were also equipped huge PT tenders with a 4-10-0 (centipede) wheel arrangement.

There was an almost forgotten earlier 4-8-4 built in 1931 by ALCO. This three-cylinder experimental locomotive carried road number 800 and was designated Class HS-1a. It did not do well on its test runs and was put to work as a hump engine at Selkirk yard.

Unfortunately, EMD F-7 passenger diesels were being delivered at the same time as the 4-8-4's. The easier servicing and quick turn-around of the F-7's made them more economical and efficient. As additional diesels were purchased, the 4-8-4's were bumped from the preferred assignments, and by 1950 all were used for lesser duties. The NYC dieselized their easternmost divisions first, and by 1953 all of the remaining 4-8-4's were pushed into Ohio and Indiana where they saw some passenger service, but were primarily used for freight duties. Their great weight restricted them to a few routes on the former Big Four lines. The 4-8-4's were not really suitable for low speed duties, but they soldiered on until 1955-1956 when their equipment trusts expired and the road completely dieselized. Unfortunately, no examples of this magnificent locomotive were preserved and all were scrapped. This is especially disappointing because these 4-8-4's were head and shoulders above any other Northern in the areas of boiler and drawbar horsepower. They were also better than any steam locomotive in the areas of weight per HP, availability, monthly and annual mileage, and total life cycle cost.


ClassRoad NumbersYear BuiltBuilder
S-1b6001-6019October-December 1945ALCO
S-1b6020-6022January 1946ALCO
S-1b6023-6025April 1946ALCO
S-2a5500June 1946ALCO

Class Details by Steve Llanso of Sweat House Media

Class S-1a (Locobase 270)

Data from the 1946 guide to Dimensions and Classifications of Locomotives seen on [] (May 2003). (Thanks to Chris Hohl for his 27 February 2018 email noting the adjustments made to the S-1a's boiler pressure and driver diameter.) Works number was 71454 in March 1945.

Firebox heating surface included 57 sq ft (5.3 sq m) of arch tubes. Don't look in the specifications for this engine's widely touted abilities. This class had a high adhesive weight, roller bearings all around, Baker valve gear, a large grate area, and valve ports designed to help the engine draw air evenly across the fire and through the tubes. They are easily recognized by their long, almost straight boiler line and "elephant ear" exhaust lifters. Note the enormous tender capacity.

Weight distribution on the trailing bogie differed considerably between this prototype and the production variant shown in Locobase 5582. The leading axle of that truck supported 48,000 lb (21,722 kg) while the rear axle bore 57,000 lb (25,855 kg). The S-1b trailing truck put 52,300 lb (23,723 kg) on each of the two.

This was the prototype; see Locobase 5583 for the production version S-1b. The S-1a's 75" drivers were soon replaced by the 79" drivers of the S-1b. Chris Hohl points out that the boiler pressure setting increased to 290 psi (20 bar) to compensate for the taller drivers. He adds that when the NYC reduced the boiler pressure to 275 psi (probably for maintenance considerations) and added 1/2" (12.7 mm) to the cylinder.

Class S-1b (Locobase 5582)

Data from the 1946 guide to Dimensions and Classifications of Locomotives seen on [] (May 2003). See also Richard W Dawson, "Road Testing of the Niagaras", Central Headlight of the New York Central System Historical Society, Vol. V, No. III (August, 1975), pp. 5-28. (Thanks to Chris Hohl for his 18 June 2015 and 11 March 2016 emails catching the range mistake in the road numbers.) Works numbers were 73779-73783 in October 1945, 73784-73793 in November, 73794-73797 in December, 73798-73800 in January 1946; 73801-73803 in April.

Firebox heating surface included 57 sq ft (5.3 sq m) of arch tubes. This is the production version of this remarkable Niagara design; see Locobase 207 for the prototype. Note that weight distribution on the trailing bogie differed considerably between the prototype and these production variants. The leading axle of that truck supported 48,000 lb (21,722 kg) while the rear axle bore 57,000 lb (25,855 kg). The S-1b trailing truck put 52,300 lb (23,723 kg) on each of the two.

Paul Kiefer, Chief of Motive Power for the NYC, is credited for the scale and quality of this design.

Tests with the prototype had shown that pulling power didn't suffer much when 79" drivers were fitted. The result was one of the finest steam passenger locomotives ever built. Integrally cast, one-piece frame and cylinders, roller bearings on all axles and on the side rod ... all the mod cons. Brian Hollingsworth (1982) notes that Baker valve gear had no sliding surfaces, so they could be fitted with needle bearings. These must have been exceptionally smooth-riding locomotives. Moreover, says Hollingsworth, the valve ports were " on the steam side, but slightly rounded on the exhaust side ... [easing] the sharpness of the blast beats, thereby evening out the draft on the fire."

And in addition to having that immense seven-axle pedestal tender to carry 92,000 lb(41,731 kg) of coal, the S-1s made use of an extensive network of trackpans to fill the tenders on the fly. As a result, the class had to make only one fuel stop during the New York-Chicago run. One of these -- 6024 -- accumulated 288,849 miles in only 11 months.

One S-1b was fitted with Caprotti poppet-valve gear and redesignated S-2a.

David R Stephenson, writing in the May 2005 Chesapeake and Ohio Historical Magazine (reproduced online at [], accessed 24 Oct 2005), puts the S-1b in clear perspective when he compares it to the Pennsy's classic T-1 duplex 4-4-4-4 (Locobase 348). After noting that the duplex solution was conceived to redress a potential problem that never quite materialized, he offers the S-1b as trump:

"Here was a locomotive," Stephenson 's verdict concludes, "that could match the T-1 at all but the highest speeds, and do it day-in and day-out without special treatment. It was moderately sized and could go almost anywhere. It didn't require particularly deft handling, was very reliable, could operate in most types of service, and didn't require specialized maintenance."

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID270 5582
RailroadNew York Central (NYC)New York Central (NYC)
Number in Class124
Road Numbers60006001-6025
Number Built124
Valve GearBakerBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)20.50 / 6.2520.50 / 6.25
Engine Wheelbase (ft / m)48.75 / 14.8648.42 / 14.76
Ratio of driving wheelbase to overall engine wheebase 0.42 0.42
Overall Wheelbase (engine & tender) (ft / m)97.21 / 29.6397.21 / 29.63
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)275,000 / 124,738275,000 / 124,738
Engine Weight (lbs / kg)471,000 / 213,642471,000 / 213,642
Tender Loaded Weight (lbs / kg)337,000 / 152,861337,000 / 152,861
Total Engine and Tender Weight (lbs / kg)808,000 / 366,503808,000 / 366,503
Tender Water Capacity (gals / ML)18,000 / 68.1818,000 / 68.18
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)46 / 41.8046 / 41.80
Minimum weight of rail (calculated) (lb/yd / kg/m)115 / 57.50115 / 57.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)75 / 190579 / 2007
Boiler Pressure (psi / kPa)275 / 19275 / 19
High Pressure Cylinders (dia x stroke) (in / mm)25" x 32" / 635x81325.5" x 32" / 648x813
Tractive Effort (lbs / kg)62,333 / 28273.8161,568 / 27926.81
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.41 4.47
Heating Ability
Firebox Area (sq ft / m2)517 / 48.05503 / 46.73
Grate Area (sq ft / m2)100.10 / 9.30101 / 9.38
Evaporative Heating Surface (sq ft / m2)4632 / 430.484823 / 447.70
Superheating Surface (sq ft / m2)1977 / 183.742073 / 192.59
Combined Heating Surface (sq ft / m2)6609 / 614.226896 / 640.29
Evaporative Heating Surface/Cylinder Volume254.78254.98
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation27,52827,775
Same as above plus superheater percentage35,78636,108
Same as above but substitute firebox area for grate area184,828179,823
Power L147,28849,761
Power MT1516.391595.70


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Wes Barris