Mr. Johann Brotan was the chief of the Gmünd Workshop of the Austrian StEG (Staatseisenbahn Gesellschaft). He invented and patented a locomotive boiler in 1902. In his construction the longboiler had only a diameter that allowed to contain the firetubes, there was no place for steam above. Instead, he has put an extra steam reservoir above the longboiler. The more important feature was however, that Mr. Brotan's boiler had no usual firebox. The steam reservoir was prolonged backwards and this was the top of the fireplace. The sides and backhead was formed from vertical steel tubes that were slanted inwards at the top, and were connected to the steam reservoir. On the bottom, these vertical tubes were connected horizontal tube forming a square frame, called "Brotan-garland". This tube had again a knee connection to the longboiler's bottom to improve water circulation. The place between the grates' front and the longboiler, actually the lower front side of the firebox back was filled up with fire bricks.
The big advantage of the Brotan boilers was, that they were built using less copper, as the firebox was constructed from steel tubes rather than copper sheets. This was very attractive for the Hungarian locomotive builders, as Hungary had very limited copper reserves. MÁV introduced an experimental project, and a few locomotives were rebuilt with Brotan boilers in the early 1900's. They were from the Classes 222, 325, 326 and 377 - the most common locomotive Classes anyway. A Class of very small locomotives, the Class 11 (2-2-0) was built only with Brotan boiler.
Many trials were performed with these engines, but the results were not really satisfying. The smaller diameter of the longboiler, and the worse heat transfer characteristics of the steel allowed only less steam production that with the usual copper firebox boilers. Besides the weird appearance of these locomotives the boiler lagging was also quite complicated in the steam reservoir area, and the connection to the longboiler. Thus no more locomotives were built with the original Brotan boiler, and the rebuilt engines were rebuilt again with conventional boilers in the '20s.
Although these experiments with the original Brotan design failed, MÁV did not give up the idea to build boilers with less copper need. Thus a new design from Mr. Defner,also an Austrian railway mechanist, who developed a modified version of the Brotan boiler, was welcome.
The Defner design kept the longboiler in its original shape and added the steam reservoir to its firebox end. The all-steel firebox with the dual-row tube wall remained as before. This solution however increased the boiler height, as the steam reservoir should be fully above the highest water level. The boiler lagging became simpler compared to the original design: it covered both the longboiler and the steam reservoir. This resulted a conical shape of the boiler at the second section. This is typical for Brotan-Defner boilers and a good spotting feature for Brotan boilered Hungarian steamers. The only exception is the Class 328, that has parallel shape boiler, as the top of the steam reservoir is not much higher than the longboiler top. The huge Brotan boiler of the Class 601 Mallet (2-6-6-0) was slightly different: it had two steam reservoirs in parallel, instead of one. Interestingly, this design is similar to the boiler of the famous Baldwin #60,000 engine. The Class 601 was built in 1914, the Baldwin #60,000 in 1928.
The all steel Brotan boiler became a desirable design feature during the 1st World War, when the limited copper resources were badly needed by the armaments industry. Actually this process already started a few years before the war, the Class 601 was designed with Brotan boiler in 1913.
The Brotan-Defner boilers had one basic weak point, the fire bricks of the firebox front wall often broke. To overcome this, Mr. Béla Fialovits, the MÁV chief engineer designed a steel front wall in the '20s, and this was applied to a few locomotives.
All Hungarian steam engines between 1914 and 1921 were built with Brotan-Defner boiler. Those locomotives, originally designed and built already before the war, were redesigned with Brotan boiler. These were the Classes 324, 375 and 376. The new Classes, 601, 342, 328 and 442 were only built with Brotan boiler. An interesting exception is the Class 342, where the two prototypes, built in 1913, were designed with copper firebox boiler, but all series engines were built with Brotan boiler. As after WW1 both prototypes were given to neighbour countries (see Distribution of MÁV Locomotives after WW1), only Brotan boilered Class 342s remained in Hungary.
The Class 651 Mallet was only built with copper firebox for MÁV, but the private company KsOD ordered similar locomotives in 1913 that were equipped with Brotan boiler.
The Brotan boilered locomotives were however considered as less powerful, than their sisters with conventional copper boiler, and this was proven by trials in the '20s. Thus after the WW1 those Brotan boilered locomotives, that were members of Classes with numerous copper firebox engines, like 324, 375 and 376, were rebuilt with conventional boiler at the major workshop overhauls in the '30s and '50s. Despite of these actions a few Brotan boilered members of these Classes survived until the end of the steam era.
Those Classes that had only Brotan boilered members (Classes 342, 442, 328 and 601) were not rebuilt, they kept this interesting feature for their whole lifetime. The neighbouring countries were more active, they have often rebuilt their Hungarian built Brotan boilered engines. MÁV sold 20 Class 328 engines to the Czechoslovakian CSD, there they were rebuilt with copper boiler in the late '20s. Some of these engines remained in Hungary after WW2, and became the only Class 328 members with copper firebox.
Today all remaining steamers with Brotan boiler are plinthed. No one is member of the MÁV "Nostalgia" operable museum stock, as the MÁV headquarter rejected any workshop job on Brotan boilers. MÁV still has tools to repair conventional copper firebox boilers for the museum stock, but the Brotan boilers need special tooling, especially for fixing the vertical steel tubes into the steam reservoir and the bottom square tube. MÁV offered the "Railway History Commity" to rebuild one plinthed engine of the Classes 328, 342 and 442 with a newly designed conventional firebox, but the Commity rejected after a long debate. They consider this as it would be a violation of the historic values; these engines were operating with Brotan boilers in their full service life.