Saxon IIIb V

The Saxon Class IIIb ${\displaystyle \textstyle {\mathfrak {V}}}$ was a twin-coupled tender locomotive built for passenger services with the Royal Saxon State Railways.

IIIb V DR Class 34.79
Number(s)	KSäStE: 501–518 DR: 34 7901 – 34 7902
Quantity	18
Manufacturer	Sächsische Maschinenfabrik, Chemnitz
Year(s) of manufacture	1889/1892
Retired	1923
Axle arrangement	1′B n2v
Track gauge	1,435 mm (4 ft 8 ^1⁄2 in)
Length over buffers	13,996 mm (45 ft 11 in)
Height	4,150 mm (13 ft 7 ^3⁄8 in)
Overall wheelbase	4,550 mm (14 ft 11 ^1⁄4 in) / 4,950 mm (16 ft 3 in)
Empty weight	37.2 t
Service weight	41.0 t
Adhesive weight	27.8 t
Axle load	13.9 t
Top speed	75 km/h (47 mph)
Driving wheel diameter	1,560 mm (5 ft 1 ^3⁄8 in)
Carrying wheel diameter	1,230 mm (4 ft ^3⁄8 in)
Valve gear	Allan
No. of cylinders	2
LP cylinder bore	420 mm (16 ^9⁄16 in)
HP cylinder bore	650 mm (25 ^9⁄16 in)
Piston stroke	560 mm (22 ^1⁄16 in)
Boiler Overpressure	12 kg/cm^2 (1,180 kPa; 171 psi)
No. of heating tubes	180
Heating tube length	3,500 mm (11 ft 5 ^3⁄4 in)
Grate area	1.82 m^2 (19.6 sq ft)
Radiative heating area	8.0 m^2 (86 sq ft)
Tube heating area	89.0 m^2 (958 sq ft)
Evaporative heating area	97.02 m^2 (1,044.3 sq ft)
Tender	sä 3T 9
Brakes	Schleifer air brakes Westinghouse air brakes (refit)

History

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

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.

Literature

• Näbrich, Fritz; Meyer, Günter; Preuß, Reiner (1983). Lokomotivarchiv Sachsen 1 (in German). Berlin: transpress VEB Verlag für Verkehrswesen.
• Preuß, Erich; Preuß, Reiner (1991). Sächsische Staatseisenbahnen (in German). Berlin: transpress Verlagsgesellschaft. ISBN 3-344-70700-0.