Between 1956 and 1960, various factories in China manufactured a total of 42 prototypes of a new 2-10-2 freight locomotive, which was based on the Soviet ОР21. From 1964 onwards, series production of a total of 4,675 additional machines, which were soon referred to as QJ, began in Datong. The abbreviation here stood for “Qianjin”, which means “progress”.

They replaced the JF and FD in heavy freight service and also pulled heavy passenger trains. In addition to the stoker and mostly smoke deflectors, their features also included the distinctive air horn. Some QJs were also built in Soviet broad gauge. A chimney similar to the Giesl ejector was tested on other machines.

Although production continued until 1988, replacement with diesel locomotives began in the eighties. After steam operations on the Chinese State Railways officially ended in 2002, the last of them disappeared from the main lines in 2003. However, the private JiTong Railway used the QJ to transport coal on its 945 km long line in Inner Mongolia until 2005 and it was also used by industrial companies until around 2010. Three QJs later found their way to the USA.

In the 1930s, the Reichsbahn had the goal of significantly accelerating freight traffic. The class 45 with a 2-10-2 wheel arrangement was developed as the most powerful freight locomotive among the standard locomotives in order to complete the classes 41 and 44 upwards. The requirements stipulated that 1,200 tonnes could be towed at 80 km/h on the flat and 1,000 tonnes at 60 km/h on a gradient of 0.5 percent. In addition, despite its many axles, the locomotive should also be able to negotiate the smallest curve radii, which was made possible by means of laterally shiftable axles and Krauss-Helmholz bogies. 

In November 1936 and June 1937 a pre-production example was procured, but it was not until 1940 and 1941 that the 26 production locomotives with the numbers 45 003 to 45 028 were delivered, which were somewhat more powerful. They proved their high power right from the start and were not only used in express freight services, but also competed with the actual express locomotives such as the class 01 in express service.

Die Lokomotive, May 1939

Although they could not reach the same top speed, they were able to maintain a high speed with an indicated continuous output of around 3,000 hp (or 2,800 hp for the two pre-production machines) even on long inclines with a heavy express train. In the event of a brief overload, it was even possible to calculate performance in the range of 3,500 hp. In addition, express train locomotives often reached the limits of traction, which happened much less frequently with the five coupled axles of the 45. Finally, the class 01 and 03 locomotives with only two cylinders developed a rough running behavior under full steam, while the 45 with three cylinders ran much more smoothly. In addition, the axle load could be changed between 18 and 20 tonnes depending on the required adhesive weight and capacity of the lines traveled. To do this, only a few bolts on the chassis had to be repositioned, which changed the load on the carrying axles. 

However, the inadequacies of the then widespread steel alloy St 47 K as a material for the boiler soon became apparent. As a result, the pressure soon had to be reduced from the targeted 20 to 16 bars. In addition, the long smoke tubes of the largest standard locomotives soon caused problems due to excessive tension. After all, such a powerful locomotive required a lot of coal, which is why two firemen always had to be used due to the lack of equipment for automatic stoking. Ultimately, plans for the procurement of about 100 more units were dropped, since the war was already raging and the less powerful but much cheaper war locomotives were preferred. In addition, the maintenance of a rail network meant too much effort for the high axle load of 20 tonnes in these times.

After the war, only one example remained with the Reichsbahn, which was tested with a forced circulation boiler, condensation tender and pulverized coal firing without success. In contrast, the machines that were refurbished by the Bundesbahn received new, welded boilers and some had a stoker, so they remained in use for a longer period of time. When they were given computer numbers in 1968, there were still three that were used as brake locomotives.

In 1920, the Hocking Valley Railroad received 16 freight locomotives from the Lehigh Valley with a 2-10-2 wheel arrangement, which, with a driver diameter of 63 inches, were too slow for their requirements. The new operator gave the almost new locomotives the class designation F-1. A few years later, six went to the Pere Marquette. The Hocking Valley was taken over by the Chesapeake & Ohio in 1930 and those ten remaining locomotives got the class designation B-1, that had been carried by two Forneys until 1913. They got bigger tenders in 1940 and were used until 1952.

On the Raton Pass between Colorado and New Mexico, the ATSF used pusher locomotives with a 2-10-0 wheel arrangement. Since there was no way to turn the locomotives on the summit, they had to run backwards down the mountain. In order to improve reverse running characteristics, some 2-10-0 locomotives with an additional trailing axle were ordered from Baldwin. This led to the Class 900 with the new 2-10-2 wheel arrangement, now known as the “Santa Fé”.

Propulsion was by four compound-acting cylinders arranged in tandem. The high-pressure cylinders were each directly in front of the low-pressure cylinders and worked together with them on the third coupled axle. To service the low-pressure cylinders, the high-pressure cylinders could be removed with an onboard crane. The third coupled axle was also the only one that didn't have wheel flanges. 

Original variant as tandem compound

The axle load of the first two driving axles and the leading axle was balanced with each other by means of a equalizing beam, as was the axle load of the rear three coupled axles and the trailing axle. Some locomotives received a special form of firebox developed by Henry W. Jacobs and Frank W. Shupert of Frisco Lines. This used perforated plates instead of staybolts and had advantages in terms of maintenance, but was not able to establish itself.

A total of 85 units of the class 900 were built. The first 40 of these were destined for Raton Pass and were coal fired. The rest were used on the line between Albuquerque and Arizona and were oil-fired. From 1905, 76 class 1600 locomotives were built, which were essentially identical to the class 900. However, since the frame had broken on this one, the frame was reinforced here, which increased the adhesive weight. However, different data for both classes could not be found.

From 1916 the locomotives of both classes were rebuilt, after which they were identical again. The boilers were equipped with a superheater and arch tubes in the boiler. Since the tandem engine required too much maintenance, it was replaced by a two-cylinder engine with simple expansion. Only the high-pressure cylinders were removed and the low-pressure cylinders enlarged.

The USRA Light Santa Fe was produced in smaller numbers than its heavy sister. Compared to this, it had drivers which were six inches smaller and a cylinder diameter that was three inches smaller. It shared the firebox design and the number of boiler tubes with the 2-6-6-2 Mallet, but the combustion chamber and the tubes were shorter.

Of 94 Light Santa Fes built, 75 came from ALCO and 19 from Baldwin. The biggest operator was the Southern, which used 50 of them as class Ss-1. The Seaboard Air Line got 15, the Boston & Albany and Duluth, Missabe & Northern got ten each, the Chicago & Western Indiana five and the Ann Arbor four.

Schematic drawing with dimensions

1922 Locomotive Cyclopedia of American Practice

The USRA standard model for heavy, slow coal trains was the Heavy Santa Fé. ALCO-Brooks delivered 135 and Baldwin 40 more. By far the largest number were the 130 members of the Pennsylvania Railroad's class N2s. The locomotives were generally considered a successful design that fulfilled their tasks satisfactorily. As early as 1923, the PRR rebuilt them with new boilers with Belpaire fireboxes and renamed them class N2sa. A fundamental problem with the Heavy Santa Fé was the very long frame, which was not cast in one piece. This warped over time, leading to increased maintenance costs.

In North Carolina, the Southern Railway operated the famous Saluda Grade with an incline that had an average of more than four percent for several miles. For use both as main locomotive and as helper on this grade and on the Old Fort Loops, the Southern turned to the 2-10-2 wheel arrangement in World War I. So they ordered 55 class Ss locomotives from Baldwin, which were delivered in 1917 and 1918 and were numbered 5000 to 5054. In general layout, these were equipped with 57 inch drivers, cylinders of 28 by 32 inches and a duplex stoker.

But for use on those heavy grades, they got some special equipment. This included taller water gauges to provide a better readout when the boiler was inclined and a second air pump to account for the heavy brake usage. Additionally, water pipes were provided which could be used to cool down the tires of the drivers. For banking passenger trains, they even got the required cab signals.

To further increase the tractive effort of its helper locomotives, the Southern also made trials with an additional engine under the tender, also called “duplex tenders”. Concerning class Ss, at least No. 5046 also got this arrangement. Here the four-axle tender was swapped for a new one with a 2-6-2 wheel arrangement. It produced additional tractive effort of 18,000 pounds and could be engaged at low speeds when the boiler produced enough steam for both engines.

In 1918, the Southern's subsidiary Cincinnati, New Orleans & Texas Pacific ordered 25 of the same locomotives from ALCO-Richmond. Since they were too slow for the flat lines they were intended, they were also transferred to the steepest grades. Later all 80 locomotives were operated at 200 instead of 190 psi. They lasted until the end of steam and were scrapped without an exception in 1951 and 1952.

After the class F-1 2-10-2s, the Southern Pacific ordered 15 F-3 in 1921 from Lima. They had larger cylinders, a larger boiler and had a trailing truck booster like their predecessors. Like most SP steam locomotives, they were oil-fired. To improve running characteristics in curves, they got lateral motion boxes on the lead drivers.

Since the SP didn't want to use the name „Santa Fe” for this wheel arrangement and didn't have real Decapod locomotives, they called all their 2-10-2s “Decks” as short form for “Decapods”. In 1922, they ordered 50 very similar locomotives from Baldwin which were designated class F-4 and delivered in a single train.

All 15 F-3 were converted to coal burning in 1924. Between 1940 and 1944, they were converted back to oil burning. Both classes were retired between 1951 and 1958.