Staatsspoorwegen 4-6-2 Locomotives in Indonesia

Class 1001/C53 (Locobase 2492)

Data from J Franco, "Four-Cylinder Compound Express Locomotive for the Java State Rys", [translated by L Derens], Locomotive Magazine, Volume XXVI [26] (14 August 2020), pp. 176-171; and E Lassueur, "Recent Locomotives for the Dutch Indies Railways," Locomotive Magazine, Volume XXVIII [28] (14 October 1922), pp. 335-338. See also dspace.dial.pipex.com/javatour/ambarawa/locos/C5317.htm, a site for the Ambarawa Railway Museum maintained by Rob Dickinson.

See Indra Krishnamurti at [] for building dates and numbers both of predecessor railways and the Indonesian State Railways.

Locobase 4744 describes the first express Pacific engines built for the Java State Railways. As good as they were, Lassueur wrote, they couldn't keep up with increasing demands, so th SS (Staats Spoorwegen) ordered this four-cylinder compound design outfitted with superheaters, piston valves, and feed water heaters.

Once C53s began hauling expresses, passenger service in Java before World War II became the fastest narrow-gauge service in the world, says Hollingsworth (1982). He wrote that the overall speed average for the 825 km (512 miles) between Batavia and Surabaya using this stylish class of Pacifics was 67 kph (41.5 mph) including 12 stops and maximum speeds reached 120 kph (75 mph).

Franco's very detailed description of this class laid out the requirements for the the class. One was to pull a train of 22-ton carriages (13-14) on level track at 100 kph (62 mph) and reach 70-75 kph (43.5-46.6 mph) up a 0.5% grade. Add 100 tons to the train, and the locomotive would still need to reach 90 kph (56 mph). All this on an axle loading not to exceed 12,000 kg (26,455 lb).

Railway staff and Werkspoor decided only a superheated four-cylinder compound would suffice; the engines also used feed Knorr water heaters. Franco's account included a two-page spread of a cutaway diagram, in which Locobase immediately noted the unusually extended smokebox that measured 2.89 m (9 ft 6 in). Firebox heating service area included that provided by four arch tubes supporting the brick arch.

Four cylinders lay side by side in line with the center of the leading bogie, high pressure cylinders mounted inside the bar frame taking live steam, all driving the leading axle, and sending the exhausted steam to the larger outside cylinders. All four cylinders admitted steam through 200 mm (7.87") piston valves.

Lassueur commented on the rarity of a line-abreast compound four-cylinder Pacific driving the front axle and claimed it was unique among Cape Gauge non-articulated compounds.

NB: The tube and flue evaporative heating surface area are calculated by Locobase using external diameters (i.e.from the water side) as was usual for North American and British Isles builders. The data given in the original article followed Continental practice, which resulted in tube & flue areas totalling 114.92 sq m (1,237 sq ft), which together with the direct heating surface area, added up to 126.2 sq m (1,358 sq ft).

During the Japanese occupation, these became C53s. Some of the class operated on local trains in East Java into the early 1970s

Class C50 (Locobase 4744)

Data from [] and "Railway Notes from Java", Locomotive Magazine, Volume 18 (15 April 1912 ), p. 78; and E Lassueur, "Recent Locomotives for the Dutch Indies Railways," Locomotive Magazine, Volume XXVIII [28] (14 October 1922), pp. 299-302.

Krishnamurti says that when rebuilt later, superheat surface increased to 39 sq m/420 sq ft. Yet the area in the 1912 LM report is given as 39 sq m (420 sq ft) on delivery.

See Indra Krishnamurti at [] for building dates and numbers both of predecessor railways and the Indonesian State Railways. Hartmann delivered 9, SLM 5.

Lassueur notes that extending the Javanese main line from Batavia to Soerabaya--a 905 km (562 mi) stretch--overmatched even the superheated 4-4-0s shown in Locobase 4721. Enlarging the express design by adding an axle and a trailing truck substantially increased both adhesive weight and grate area.

The design was expected to draw a 300-ton train on a relatively light axle load, achieve a top speed of 80 kph (50 mph) and reach 64 kph (40 mph) on a 0.5% grade. Lassueuer reported that the class "easily accomplished their tests, allowed great improvements to bemade in the traffic working" But increasing demand required a still bigger design; see Locobase