SS 800 class

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

Built between 1912 and 1920, the 800 class were designed to handle heavy traffic over mountainous terrain on the island of Java. Some were later transferred to Sumatra as traffic demands increased there, and the 800 class began to be displaced by newer locomotives from the 1920s. Reclassified as F10 during the Japanese occupation, they were withdrawn in the 1970s, and two have been preserved as static exhibits.

After 1900, the railways and its traffic saw expansion on the island of Java. Many sections of railway were steep and heavily graded, requiring powerful locomotives that also were able to efficiently negotiate tight curves. A variety of gauges were used, but the majority were laid to the gauge of 1,067 mm (3 ft 6 in). The SS 500/BB10 class were 0-4-4-2T Mallet locomotives, but, by then, lacked the strength to cope with increasingly heavy trains. A six-coupled Mallet, the SS 360/CC10 class, was introduced. These locomotives, despite being able to negotiate tight curves and handle heavy trains, proved cumbersome in maintenance, with leakage from the flexible steam pipes to the leading chassis.^[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, with the arrangement of the axles permitting negotiation of tight curves; the four central axles were rigid, and the leading and trailing coupled axles allowed some sideplay.

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

To permit negotiation of 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 afflicted 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-pitched, in consideration of the gauge, so for stability the side tanks were positioned as skirt tanks below the footplate level, and could almost be overlooked. A large rear 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 required. Despite appearances, the class 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 vent.

The first of the class was ordered as one single 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 unique wheel arrangement, and to the contemporary RMS Titanic, they acquired the nickname 'Javanics'.^[8] This also gave rise to Javanic as a generic name for the wheel arrangement of the class, just as Atlantic and Pacific had already become established.^[9][10]

During the Great War, the Netherlands were neutral and continued to trade with Germany. Wartime restrictions meant that 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 running shed.^[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 SS 1600/DKA CC50 Mallets were despatched in service, the 800s were gradually transferred to sections 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 the Japanese occupation of the Dutch East Indies during the Second World War and the proclamation of independence in 1945, Djawatan Kereta Api ('Indonesian State Railways') was formed on 28 September 1945. A locomotive reclassification scheme had been implemented,^[iv] with the class being designated as F10, with running numbers F1001-F1028. The F denoted a locomotive with six driving axles.^[6] After the Indonesian War of Independence ended in 1949, some reorganising and renaming of the state railway occurred, but this did not affect the F10 class.

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

All steam in Indonesia was withdrawn amidst dieselisation in the 1970s. Locomotives were scrapped and cut up at their old running sheds. In West Sumatra, a number of scrapped F10s 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 – the Ambarawa Railway Museum, Ambarawa^[12]
• F1015 – the Transportation Museum in Taman Mini Indonesia Indah, Cipayung^[13]

Some sources^[v] 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
• DKA class E10