The Avonside Engine Company offered a range of standard narrow gauge tank locomotives that could be ordered with various gauge and cylinder diameter combinations. In order to ensure a long service life and low wear, some assemblies were made of harder steel than actually required and the friction surfaces on wear-intensive parts were made wider.

One of the types had the wheel arrangement 0-6-2T and was successfully exported to South America and India. The example shown was built for the gauge of 2 feet and 6 inches and had cylinders with a diameter of 12 and a stroke of 18 inches. Variants with cylinder diameters ranging from nine to fourteen inches were available for the same gauge. For the 2 feet gauge, cylinders with a diameter of between nine and twelve inches were provided.

The D VIII was developed for local railways with steep gradients, where the conventional local railway locomotives no longer had sufficient power. The main focus was on the line to Berchtesgaden, which had gradients of up to 4 percent. The construction was carried out with three coupled axles, but these alone could not carry the weight due to the requirements. For this reason, a carrying axle was necessary, but initially the question arose as to whether this should be located in front of or behind the coupled axles. 

Since the D VIII was primarily intended to drive slowly uphill and quickly downhill on the intended routes, the designer Richard von Helmholtz recommended a trailing axle to ensure smoother running. This was connected to the last coupled axle with the Krauss-Helmholtz bogey designed in such a way that the deflection of the trailing axle also shifted the coupled axle by a few millimeters in the opposite direction, making negotiation of curves easier.

From 1888, a total of 18 engines were built for Bavaria in several small orders, of which the last were delivered in 1903. Although series production had already ended ten years by then, the Augsburg Localbahn ordered three engines of the same design in 1913. It is particularly remarkable that they even ordered a fourth engines of the same type in 1937. At this point Krauss had already merged with Maffei and the design of the D VIII was almost 50 years old.

At the Reichsbahn, 17 of the 18 Bavarian locomotives were numbered in the class 98⁶ and retired by the end of the 1930s. Only one locomotive survived until 1944 and another came to Austria in 1945, where it was used until 1959. At the Augsburger Localbahn, two of the locomotives were sold to a chemical company in 1956 and the other two were eventually retired the following year.

A variant of the D VIII was the D X, which was very similar to it but slightly lighter. It was built in 1890 and 1893 in two series of six and three and was in service until 1931 as class 98⁷⁷. With a service weight of 42.7 tonnes, they achieved an indicated output of 220 kW and also a top speed of 45 km/h.

The D XI, also known by its later designation PtL 3/4, was the most numerous of the Bavarian local railway locomotives. It was designed and built simultaneously by Krauss and Maffei and procured over a period of 19 years. Externally, they were very similar to the D VIII, which had been in production for a number of years, but they were intended more for routes on flat land and were therefore somewhat lighter and weaker. On the other hand, the coal reserves were larger, since the greater weight on the trailing axle, which was placed far to the rear, had less of a negative effect on the driving characteristics on flat land than on inclines.

Due to the long distance of the trailing axle, this was linked by a Krauss-Helmholtz bogie, as had already been used on the D VIII. The brakes on the locomotive were also state-of-the-art, and despite the changed area of operation, a Riggenbach counter-pressure brake was used in addition to the counterweight brake and the modern Westinghouse air brake.

In addition to the state railway, the LAG also bought eight engines from Krauss, which were later bought up by the state railway. There were also three examples that came to the state railways from the Murnau–Kohlgrub–Oberammergau light railway via the LAG. Thus the total number of D XI or PtL 3/4 reached 147 copies until 1914. A model derived from them was the Palatinate T 4^II, which was only built three times and had slightly different dimensions. After the war, all engines came to the Reichsbahn and became the class 98^4-5. About half were retired in the early 1930s. After a few losses in World War II, the Bundesbahn took over 56 units, the last of which was in use until 1960.

William Frank Pettigrew, who had taken up the post of Chief Engineer at the Furness in 1896, was tasked with designing a powerful locomotive for mineral train service. The solution was a six-coupled tank locomotive with a trailing axle, known in Britain as a “radial tank”. It was also given the name “Cleator Tank” because it was primarily intended for use on the Cleator and Workington Junction Railway in West Cumberland.

The boiler, cylinders and driving wheels were used almost unchanged from the standard class 7 freight locomotive. These were 0-6-0 tender locos, which became known as the Class D3 in the Bob Rush works. The Cleator Tanks of the first series were built in only three pieces by Sharp, Stewart & Co. with the numbers 112 to 114 and were later given the designation L1 by Rush.

In 1904 a reinforced variant was presented, which was listed as the Class 98. The area of application now no longer included freight trains, but passenger trains on commuter routes. In return, they had a four-inch larger driver diameter, ten psi higher boiler pressure, and larger reserves. The larger coal bunker can be clearly seen in comparison with its predecessors. For operation on a section with a lower permissible axle load, the compensation pipes between the water tanks were fitted with a special device that only filled the rear tank and thus reduced the load on the coupled axles. 

Locomotive Magazine, August 1904

Five of the new variant were initially produced by Nasmyth, Wilson & Co. and five by North British. Another batch of six followed in 1907, supplied by North British. For better weight distribution, they had shorter side tanks, a larger back tank and came to a greater mass. At Rush, the 1904-style locomotives were designated L2, while the newer ones were designated L3.

A few years after the tank locomotives known as “Cleator tanks”, Pettigrew developed another type, now again intended for hauling iron ore to the blast furnaces on the coast at Workington. In return, they received coupled wheels that, at 4 ft 7.5 in, were even smaller than those of the class 112. Although designated class 94 by the Furness Railway from the number of the first engine built, they are now also known as class L4.

The first two examples, numbered 94 and 95, were completed in 1912 and had a smokebox superheater. Since this apparently did not meet the expectations placed in it, numbers 92 and 93 from 1914 were again built without this superheater. The space thus freed up in the smoke chamber was used to lengthen the actual boiler barrel instead, thus enlarging the tube heating surface.

All four were still in use when the Furness Railway was merged into the LMS in 1923. The first two examples were still unchanged, since the removal of the superheater would have required a completely new boiler. The four locomotives were retired between 1929 and 1935, with number 95 being the first to be affected and 94 being the last.

No. 1560 after the weight distribution adjustments

Locomotive Magazine, March 1908

Schematical drawing

Locomotive Magazine, May 1907

After the L1, Ivatt developed another tank locomotive for the GNR for use on the city lines of London. In order to be better suited for higher speeds, there were only three coupled axles with 5 ft 8 in wheels. As with the L1, the first example of the N1 was too heavy for the Metropolitan Lines. In the following examples, the axle load on the coupled axles was reduced by placing more weight on the trailing axle. This was done by moving them further back and shortening the front water tanks and accommodating more water behind the cab. A total of 56 units were produced by 1912, all but six of which were again equipped with a condensation device. The latter six were used in the West Riding of Yorkshire.

Initially, most N1s remained in service in London. During World War I, two were sold to the War Office, one of which was used to build an armored train. In the years that followed, superheaters of the Schmidt type were installed in eleven units. From 1920 Gresleys N2s replaced the N1s in passenger train service. The N1s continued to operate in north London, but mostly to haul empty passenger coaches and freight trains. After the locomotives had come to the LNER, the remaining ones were fitted with Robinson type superheaters and the eleven that had already been converted were also refitted. Gradually more locomotives came to Yorkshire where the condensing facilities were removed. Most ended up with British Railways, the last being retired in 1959.

Locomotive Magazine, January 1921

Schematical drawing with dimensions

Locomotive Magazine, January 1921

As a replacement for Ivatt's N1, Nigel Gresley developed the N2, which was again a tank locomotive with a 0-6-2T wheel arrangement and a driver diameter of 5 feet 8 inches. They were superheated from the factory and weighed a little more than the N1. Because the valves were mounted on top of the inside cylinders, the boiler had to be mounted relatively high. This necessitated a flat chimney to fit the Metropolitan Line's loading gauge. The first 60 examples were built in 1920 and 1921 and operated in north London, with Kings Cross as their home station. They always had enough to do, as new residential areas were constantly being developed in the north and these were connected via Kings Cross. Typical wagon material consisted of the four-part passenger wagons known as “quad-art”, which were connected via Jakobs bogies and from which one or two sets were usually pulled.

After the British railway administrations were grouped, the LNER had a further 47 units built between 1925 and 1929. These consisted of different versions, some of which did not have condensation devices and had different braking systems. These were used in Scotland on the Edinburgh, Glasgow and Dundee suburban railways. Speed limits sometimes had to be introduced on winding routes because the engines had a high center of gravity. Over time there have been several conversions in which various forms of superheaters have been installed. All examples built were still in use when British Railways was formed in 1948. Gradually, diesel railcars took over the tasks of the N2, so that they gradually disappeared between 1955 and 1962. One example is still available today and is roadworthy. It has had the GNR's apple-green livery since 2009.

Under the designation T 9, the Prussian State Railways combined various types of tank locomotives with three coupled axles and one leading or trailing axle. They were mainly be used for tasks for which the T 3 was too weak. Originally 57 engines were built from 1891 for different lines with small differences. While the later T 9² and T 9³ had a leading axle, the original T 9 and T 9¹ had a trailing one.

After the T 9 was based on a design by Krauss in Munich, a large number of it's development T 9¹ were ordered from various manufacturers in Prussia. The weight and dimensions increased only slightly, but the diameter of the coupled wheels was increased to 1,350 mm. Thus, the maximum permitted speed could be at 60 km/h. The state railway variants of the T 9 were only certified for 45 or 50 km/h, only the Hessian locomotive was also permitted for 60 km/h.

Cöln 7270 in September 1982 in Bochum-Dahlhausen, one of the last engines preserved and scrapped by now

MPW57

A total of 426 engines were built up to 1901, of which 231 came to the Reichsbahn in 1925 and were mostly assigned to the 90^0-2 class. Ten pieces were incorrectly labeled as the 91 class, which was actually intended for the T 9² and T 9³. Like their predecessors, most of the T 9¹ were retired by around 1930 and some were sold to private railways. During the Second World War, some engines came back from Poland, the last of which survived until 1953.