The most numerous class of Irish locomotives was a six-coupled goods locomotive, which was purchased 111 times over a period of 37 years. It wore class number 101 on the GS&WR and was designated class J15 on the Great Southern from 1925. Thanks to their low axle loads, they could also be used on branch lines, where they even pulled passenger trains.

Schematic drawing in original state

Locomotive Magazine, January 1918

The design was by Alexander McDonnell, who was Locomotive Superintendent from 1864 to 1883. Most examples were built at GS&WR's Inchicore works, but a smaller number came from the UK by Beyer, Peacock & Co and Sharp, Stewart & Co. Some of the examples built at Inchicore used components of old 0-4-2 goods locomotives.

Schematic drawing in rebuilt state

Locomotive Magazine, February 1918

All locomotives built up to 1881 had cylinders with a diameter of 17 inches and a stroke of 24 inches. The boiler was initially made of iron and could therefore only be operated at a pressure of 140 psi. Later boilers were steel and could be approved for 150 and later 160 psi. From 1882, cylinders with a diameter of 18 inches were installed.

An attempt to increase efficiency was number 165, built in 1888 with a compound engine with cylinders of 18 and 26 inches. As expected, this was more economical than its sisters, but could not muster the same pulling power. In 1896 it got the same cylinders as her sisters with simple steam expansion. The larger boilers that were installed in the last locomotives built in 1902 and 1903 were more successful. Later, a large number of locomotives were fitted with the same boiler. Many also got superheated boilers with Belpaire fireboxes. 

In heavy goods train use, the class 101 could pull up to 45 loaded cars. Limits were set only by the relatively low adhesive weight on wet tracks. In addition, the relatively small boiler did not have very much power reserve. After more powerful goods locomotives were procured at the turn of the century, the operational area of the class 101 shifted almost entirely to branch lines. Nevertheless, new locomotives were introduced in 1929 and 1934 with the classes 700 (J15a) and 710 (J15b), which were based directly on the class 101. The last copies were not retired until 1963.

Due to the strikes that took place at the GS&WR's Inchicore works in 1902, Superintendent Robert Coey had the class 355 built by Sharp, Stewart & Co. These were seven 0-6-0 freight locomotives, which stood out due to their high boiler. Their problem was that the first driving axle had a particularly high axle load. 

Rebuilt to 2-6-0

Locomotive Magazine, March 1918

Therefore, from 1907 onwards they were rebuilt to the 2-6-0 wheel arrangement, with the axle load of the first driving axle now being slightly lower than that of the other two. Instead of a bissel axle, a leading axle with a radially adjustable bearing was used, and a longer smokebox was also installed. They were withdrawn between 1955 and 1960.

After Edward A. Watson became acquainted with the Star class at the GWR, he designed the class 400 for the Great Southern & Western based on it. Similarities included, above all, the 4-6-0 wheel arrangement and the four cylinders with simple expansion. In 1916 only the prototype with the number 400 was initially built in Inchicore. Its problem was that the frames were too thin and there were inadequate bolsters for the steam pipes, which often led to them breaking. In addition, the consumption of water and coal was too high.

From 1921 onwards, further locomotives were built, which received some improvements. Together with others from Armstrong Whitworth, the number rose to ten. However, since these were not entirely convincing, the seven remaining locomotives were rebuilt between 1927 and 1937 with two larger cylinders. Some were almost completely rebuilt, while the changes to others were limited. In this form they were successful, so that the last one was used until 1961.

sectional drawing

Locomotive Magazine, September 1901

The class A were the heaviest locomotives in Ireland at the time they entered service. Their job was to haul heavy express trains between the east and west coasts. Due to their high axle load, they could not be used everywhere. The first locomotive was rebuilt as early as 1916, with a superheater and larger cylinders. Due to differences, the rebuilt locomotives were designated as Class A1 or As. With the exception of one locomotive, all the others were only retired between 1954 and 1959.