The Saxon Class IIIb was a twin-coupled tender locomotive built for passenger services with the Royal Saxon State Railways.

IIIb V
DR Class 34.79
Type and origin
BuilderSächsische Maschinenfabrik, Chemnitz
Build date1889/1892
Total produced18
Specifications
Configuration:
 • UIC1′B n2v
Gauge1,435 mm (4 ft 8+12 in)
Driver dia.1,560 mm (5 ft 1+38 in)
Carrying wheel diameter1,230 mm (4 ft 38 in)
Wheelbase:
 • Overall4,550 mm (14 ft 11+14 in) / 4,950 mm (16 ft 3 in)
Length:
 • Over beams13,996 mm (45 ft 11 in)
Height4,150 mm (13 ft 7+38 in)
Axle load13.9 t
Adhesive weight27.8 t
Empty weight37.2 t
Service weight41.0 t
Boiler:
No. of heating tubes180
Heating tube length3,500 mm (11 ft 5+34 in)
Boiler pressure12 kg/cm2 (1,180 kPa; 171 psi)
Heating surface:
 • Firebox1.82 m2 (19.6 sq ft)
 • Radiative8.0 m2 (86 sq ft)
 • Tubes89.0 m2 (958 sq ft)
 • Evaporative97.02 m2 (1,044.3 sq ft)
Cylinders2
High-pressure cylinder650 mm (25+916 in)
Low-pressure cylinder420 mm (16+916 in)
Piston stroke560 mm (22+116 in)
Valve gearAllan
Loco brakeSchleifer air brakes
Westinghouse air brakes (refit)
Performance figures
Maximum speed75 km/h (47 mph)
Career
NumbersKSäStE: 501–518
DR: 34 7901 – 34 7902
Retired1923

History

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Following the success with the compound locomotives of Class VIb V, corresponding locomotives were procured for hauling passenger trains. Based on the design of the Saxon IIIb the Saxon Engineering Works (Sächsische Maschinenfabrik) built a compound engine. In the years 1889 and 1892 a total of 18 units of the IIIb V were built for passenger train duties. Because the engines apparently did not prove themselves, no further orders were placed.

In 1920, the Deutsche Reichsbahn took over some of the locomotives, but only two remaining engines were included in the new numbering scheme in 1924: numbers 34 7901 and 34 7902.

Design features

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The locomotives had a boiler made from three shell rings with a semi-circular cover which, in the area of the firebox, was tucked in it between the frame plates. The boiler was fed by two non-sucking injectors.

The steam engine was designed as a twin-cylinder compound engine with interior Allan valve gear. The high-pressure cylinder was placed on the right, the larger, low-pressure cylinder on the left. They drove the second coupled axle.

The driving axles were fixed in the frame, the leading carrying wheels were designed as a Novotny-Klien axle.

The locomotives left the factory equipped with Schleifer compressed air brakes; these only braked the engine, however. Later, all the locomotives were fitted with Westinghouse air brakes. The locomotiven were coupled to tenders of Saxon Class sä 3 T 9.

References

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  • Näbrich, Fritz; Meyer, Günter; Preuß, Reiner (1983). Lokomotivarchiv Sachsen 1 (in German). Berlin: transpress VEB Verlag für Verkehrswesen.[page needed]
  • Näbrich, Fritz; Preuß, Reiner; Meyer, Günter (1984). Lokomotiven sächsischer Eisenbahnen, Schnellzug- und Personenzuglokomotiven (EFA 2.1) (in German). Düsseldorf: Alba. pp. 144–148, 210. ISBN 3-87094-096-4.
  • Preuß, Erich; Preuß, Reiner (1991). Sächsische Staatseisenbahnen (in German). Berlin: transpress Verlagsgesellschaft. ISBN 3-344-70700-0.[page needed]
  • Weisbrod, Manfred; Müller, Hans; Petznik, Wolfgang (1976). Dampflokomotiven deutscher Eisenbahnen, Baureihe 01–39 (EFA 1.1) (in German) (3rd ed.). Düsseldorf: Alba Buchverlag. pp. 196–198. ISBN 3-87094-081-6.