Indonesian Railways class SS 800 / F10

The SS 800 class, later reclassified as the F10 class, were a class of 28 2-12-2T steam locomotives for Staatsspoorwegen, the state-owned railway of the Dutch East Indies, now Indonesia. They were one of very few twelve-coupled locomotives to be built. They were built by Hanomag of Germany and later Werkspoor in the Netherlands

After 1900, railways and railway traffic were expanding on the island of Java. Lines were steep and heavily graded, needing powerful locomotives that were also able to traverse a tight curve. A variety of gauges were used, but the majority were of 1,067 mm (3 ft 6 in). The SS 500 / BB10 class were 0-4-4-2T Mallet locomotives, but these were no longer able to haul the growing trains. A six-coupled Mallet, the SS 360 / CC10 class, was introduced. These were able to meet the two requirements, but were considered difficult for maintenance, especially for leakage from the flexible steam pipes to the leading bogie.^[3]

There was a demand for a locomotive with as many driven axles as the Mallets, but without the complexity of articulation.^[3] Hanomag produced a design for a 2-12-2T tank locomotive. The four central axles were rigid, the leading and trailing coupled axles allowed some sideplay, and this permitted tighter curves.

Apart from the unusual number of coupled axles^[i] and the overall large size for a narrow gauge locomotive, their construction was quite conventional, although using the latest techniques of 1912.^[4]

To allow passage around tight curves, the leading and trailing coupled axles were arranged as a form of Gölsdorf axle with linear sideplay.^[ii] The first and last coupling rods also had vertical pin hinges to allow sideways movement. Leading and trailing carrying axles were carried in Adams radial axle boxes.^[1] Although the sideplay allowed the locomotives to traverse a curve down to 140 m radius, the linear movement also led to rapid flange wear,^[iii] and the curve restrictions had to be increased in service.

They were superheated, with Schmidt superheaters in 18 flues.^[1][4][5] Piston valves allowed the raised steam temperature of superheating without the lubrication problems that affected some locomotives of this era.

The chimney had the internal opening displaced forwards within the decorative outer casing, and a small snifting valve was hidden underneath it, behind the flue.^[1] In later years the locomotives were fitted with a plain 'stovepipe' chimney instead. To allow easy coasting down the long gradients, with the regulator shut, there was an unusual valve behind the cylinders under the driver's control that linked the two ends of the cylinder and so avoided any engine braking effect.^[1]

The boiler was already large and high-mounted, in relation to the gauge, so for stability the side tanks were set low-down as skirt tanks below the footplate level, and could almost be overlooked. A large back tank was also provided below the coal bunker. Water was easily available in Java and the distance between watering points was short, so a large capacity was not needed. Despite appearances though, they carried a third more water than the earlier Mallets.

In consideration of the hot climate, the cabs were spacious and the side windows were fitted with sliding louvred sun screens. There was also a large clerestory roof ventilator.

The first of the class was ordered as a single example prototype. A production batch, bringing the total to ten, followed shortly afterwards. Further batches were ordered at intervals afterwards. No important variations between the batches, or by the different builders, are recorded.

In reference to their size, the unprecedented wheel arrangement, and the other recent enormous transport innovation of that year, they acquired the nickname 'Javanics'.^[8] This also gave rise to Javanic as a generic name within the Whyte notation for the 2-12-2 layout, just as Atlantic and Pacific had already become established.^[9][10]

During World War I, the Netherlands were neutral and continued to trade with Germany. However locomotives were not available from Hanomag and so new ones were ordered from Werkspoor instead. After the war, in 1920, a last batch were obtained, this time again from Hanomag.

Initially Staatsspoorwegen used the locomotives in the mountainous Parahyangan (Preanger) region of West Java, based at Bandung locomotive depot.^[3] Railways in the Dutch East Indies at this time consisted of several isolated systems, separated by long distances, and of several different gauges. The locomotives were designed for a minimum curve radius of around 150 m and although they coped with this, flange wear was excessive. Over their careers, and once the later large SS 1600 Mallets were available, they were gradually moved to lines with gentler curves.^[9]

Around 1920, coal mining around Ombilin in West Sumatra was becoming important. Five of the SS 800 locomotives were moved there, transferred to the SSS (Staatsspoorwegen ter Sumatra's Westkust) and renumbered as H130–H134.^[11] Three were locomotives from Java, two were newly built in 1920 and may have been delivered there directly from Hanomag.^[9]

After Japanese occupation during World War II and the Proclamation of Indonesian Independence in 1945, Djawatan Kereta Api ('Indonesian Railways') was formed on 28 September 1945. There was a general renumbering of locomotives and these became the F10 class, numbered F1001-F1028, the F indicating the six driving axles.^[6] After the Indonesian War of Independence ended in 1949, there was some reorganising and renaming of the railway company, but this did not affect the F10 class.

In their last years F10s were also found in East Java, on lines such as Malang–Blitar and Jember–Klakah–Lumajang, working local trains of mixed passengers and goods.^[3]

All steam in Indonesia was withdrawn during a process of dieselisation in the 1970s. Locomotives were scrapped and cut up at their old depots. In West Sumatra, a number of scrapped F10 were seen in January 1981 and F1024 was identified as derelict at Padang Works, with F1028 derelict at Solok at the same time.^[11]

Two are preserved in Java in static condition:

• F1002 – Indonesian Railways Museum at Ambarawa^[12]
• F1015 – Transportation Museum at Taman Mini Indonesia Indah, Cipayung^[13]

Some sources^[iv] claim that in 1986, F1015 was taken to the transport-themed Expo 86 and 'SteamExpo 86' in Vancouver, Canada, as part of the Indonesian exhibition. This cannot be confirmed. F1015 had been restored at Padang works in 1985.^[11]

• History of railways in Indonesia
• Class E10