The class 50 was developed to be able to replace the heaviest freight locomotives with low axle loading from the various state railways. With the wheel arrangement 2-10-0, it had a considerable size, but due to the axle load of only about 15 tonnes, it could be used on almost all secondary lines. The most important class to be replaced was the Prussian G 10, which was present in very large numbers. Compared to this, only one leading axle was added in order to be able to increase power despite the same axle load. 

The class designation HXN5 of China Railway stands for a heavy freight diesel locomotive designed by General Electric. A total of 700 of the model called ES59ACi were ordered in 2005. They only have a cab at one end and are powered by the 16-cylinder GEVO engine only used in export locomotives. At 6,250 hp, they are among the most powerful single-engined diesel locomotives in the world.

For the branch line between Gortatlea and Castleisland in Kerry County, the GSWR had two vehicles built in Inchicore in 1890, which can be described as precursors to the steam railcar. Since commercial traffic with regular passenger trains could hardly be carried out on the line, an extra light tank locomotive was combined with a passenger compartment. However, according to Locomotive Magazine, issue May 1903, the passenger compartments were not actually used for their intended purpose.

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”.

Since the S 10 was found after a short time to consume a lot of water and coal, the development of a more economical locomotive with a compound engine was started. Although the designation suggests otherwise, the S 10¹ was not related to the S 10 in terms of design. The class only included express locomotives with a 4-6-0 wheel arrangement, in reality the S 10¹ was a completely new design and was not based on the P 8 like its predecessor.

The DRS-6-4 series included road switchers that had a total of six axles, four of which were powered. The three less powerful variants each had a six-cylinder with 660, 750 or 1,000 hp, with only the most powerful variant having a turbocharger. 

When the locomotives of the classes T 10 and T 12 had reached their power limits, the T 18 was developed as the last tank locomotive for passenger trains, which was still taken over by the Prussian State Railways. Due to their successful construction, further orders could also be received from other railways at home and abroad. In order to be able to avoid turning the locomotives at the termini and to be able to reach the same speed in both directions, a tank locomotive with a symmetrical wheel arrangement was chosen. Tender locomotives, which could also reach high speeds in reverse, only appeared later, and in the case of tender locomotives with an asymmetrical wheel arrangement, the running smoothness when reversing was usually not entirely convincing.

The kkStB network included many lines on which both passenger and express trains could not travel faster than 70 or 75 km/h due to the topographical conditions. When the four-coupled locomotives were no longer sufficient for these services, it was necessary to switch to a six-coupled one. At that time, the 4-6-0 wheel arrangement was popular in other countries, but it didn't offer much space for a large firebox between the coupled wheels. Since a trailing axle was needed due to the low-energy coal in Austria, the class 110 for faster trains had been introduced as early as 1905 with a 2-6-2 wheel arrangement. So Gölsdorf also developed the class 329 with this wheel arrangement, but a driver diameter of only 1,614 mm.

Since articulated freight locomotives in the 1920s did not yet reach the same speeds as ten-coupled locomotives, Union Pacific had the class 9000 developed with six coupled axles in one frame. The unique wheel arrangement with a four-wheel leading bogie, six sets of drivers and a two-wheel trailing truck was called “Union Pacific” by the UP. The 1926 prototype was officially given the class designation UP-1, while further batches were designated UP-2 to UP-5.

In 1939, the Kenya-Uganda Railway was the first one to order Garratts in the “Double Northern” layout, i.e. with the wheel arrangement 4-8-4+4-8-4. With their weight now being distributed over more axles, a more powerful locomotive could be carried on metre gauge lines. The drivers were now 54 inches compared to the 43 inches of their predecessors. They were designed to the maximum of the Indian metre gauge loading gauge, hence the low chimney and dome as shown on the works photo.

When the Pfalzbahn wanted to try out new ways of temporarily increasing the tractive effort of express locomotives, they ordered a locomotive from Krauss that was called “Dr. von Clemm”. Here a Helmholtz patent was used, which Kraus had already used on the Bavarian AA I and which provided for an additional, lowerable axle with an additional steam engine. While the basic construction of the AA I corresponded to the wheel arrangement 4-2-2 and where the additional axle was installed in front of the coupled axle in the frame, the P 3^II was a 4-4-2 (Atlantic), in which the additional axle was placed in the centre of the bogie. 

Among the IRS standard locomotives, the class ZB was a 2-6-2 with an axle load of six tons for a gauge of two and a half feet (762 mm). Distinct features were the outside frames and the Belpaire firebox that was optimized for burning low-grade coal. The design was introduced in 1925 and larger numbers were built by different manufacturers until the fifties.

The class R-1 Mountains were the last steam locomotives ordered by the Boston & Maine. They were among the heaviest Mountains and were built in four batches between 1935 and 1941. Initially five R-1a were built, in 1937 another five R-1b, in 1939 three R-1c and finally five R-1d. All locomotives were given names that were determined in a competition.

The 4-8-2 locomotive of the class 12A was the last design by D.A. Hendrie for the South African Railways. It was based on the class 12 that had been introduced before World War I. The biggest change was that the area of the firebox was enlarged by 30 percent. All in all, they had the maximum size that was possible for a Mountain locomotive on cape gauge.

Although the designation suggests a passenger locomotive, the P 4 was an express locomotive built by Maffei for the Palatine Railway in 1905 and 1906. It was based on the Bavarian S 2/5, but had a larger grate that was situated completely behind the rear driving axle. Because of this, the wheelbase between the rear driving axle and the trailing axle was made longer and the trailing axle needed a radially adjustable bearing. The driver diameter of 2,010 mm or 6 ft 7 in ensured a low rotational speed when running fast.

The PLM operated some main lines on which important express trains with high passenger numbers had to be hauled. One of these was the north-south connection from Calais to the Riviera, on which the “Train Bleu” ran with many passengers from Great Britain. Since the Pacifics were not sufficient there, one of the first Mountain locomotives in Europe was developed in 1925 with the 241 A 1. The requirements included that they should be able to haul 600-tonne express trains at 110 km/h on the level and at 75 to 80 km/h on the line between Laroche and Dijon with gradients of 0.4 to 0.8 percent.

The D, introduced in 1925, was the first standard electric locomotive of the SJ that was built in greater numbers. It had the wheel arrangement 1-C-1 and two traction motors which worked on a common crank axle and coupling rods. In the first batches, each traction motor had 610 kW and the locomotive body was made of wood with gangways on the fronts. The freight variant with a gear ratio for 75 km/h was designated Dg, while the passenger variant with a gear ratio for 100 km/h was designated Ds.

The GtL 4/4 was a local railway locomotive for freight traffic with four coupled axles. Although the first were built as early as 1911, the majority of this class was procured during the period of the Deutsche Reichsbahn. In contrast to the previously procured BB II, the chassis no longer contained a bogie, but all axles were mounted in one frame. The Gölsdorf system was used to run through tight curves and the second and third axles were designed with lateral movement. This made maintenance easier and also made two of the four cylinders superfluous, which proved to be a great advantage, especially on local railways. The use of superheated steam, which was already state of the art at that time, also contributed to reducing operating costs.

When the Swedish SJ started to electrify many secondary lines in the thirties, they needed powerful electric locomotives with a low axle load. They were not only to be used for passenger and freight trains, but also as a shunter. Features of these locomotives were a centrally mounted cab with pantograph on the roof and sprung traction motors. Anyway, the first variant called Ha built from 1939 did not have satisfying running characteristics and had to be limited to 70 km/h instead of the planned 90 km/h.

In 1928, the Boston & Maine procured their first 20 Berkshire-type locomotives from Lima. This meant a leading axle, four driving axles and a two-axle bogie under the firebox. Thanks to the bogie, the grate area could be exactly 100 square feet. After the 20 locomotives of the class T-1a, another five were ordered in the following year and classed T-1b. These were slightly heavier than the T-1a, which were later upgraded to the same level.