The reference for locomotives and railcars
Saxon IIIb T
German Reichsbahn class 9872
Germany | 1875 | 42 produced
No. 634 “Dioptas”, formerly Muldenthal Railway Company
No. 634 “Dioptas”, formerly Muldenthal Railway Company
works photo Hartmann

The Royal Saxon State Railways combined two types of local railway tank locomotives as IIIb T, which had the wheel arrangement 0-4-2T and were similar in structure. Another similarity was the fact that about half of the engines had originally been procured by very short-lived private railways, but later came to the state railways.

A series was ordered in 1875 by the Muldenthal railway company from Schwartzkopff in Berlin. The locomotives were used on the 83 km long branch line between Glauchau and Wurzen until the line and vehicles were ceded to the state railways in 1878 due to financial difficulties. Further locomotives were ordered by the Chemnitz-Aue-Adorfer Eisenbahn-Gesellschaft from the Sächsische Maschinenfabrik in Chemnitz. Their area of operation was the 115 km long line from Chemnitz via Aue to Adorf, as well as a 9 km long branch line from Zwotental to Klingenthal. This railway company was merged into the state railways in 1876 after only four years of existence.

Between 1889 and 1892, the Saxon State Railways had twenty more units made in three series, which were more powerful than their predecessors. They were characterized by a boiler pressure of ten instead of nine bars and were about 20 cm longer than their predecessors. A total of 42 pieces of the series now known as IIIb T were created. The Reichsbahn took over nine more of these locomotives, which became the class 9872. They were decommissioned by 1929, only one remained in service until 1934 as a works locomotive in the Reichsbahn repair shop in Leipzig.

Built1875, 1889-1892
ManufacturerBMAG, Hartmann
Axle config0-4-2T 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length28 ft 9 3/8 in
Wheelbase13 ft 2 11/16 in
Fixed wheelbase9 ft 2 1/4 in
Service weight91,712 lbs
Adhesive weight67,241 lbs
Axle load33,731 lbs
Water capacity951 us gal
Fuel capacity2,205 lbs (coal)
Power sourcesteam
Estimated power235 hp (175 kW)
Optimal speed12 mph
Top speed31 mph
Starting effort12,953 lbf
Power Plant
Driver diameter55.9 in
Boiler pressure145 psi
Expansion typesimple
Cylinderstwo, 16 5/16 x 22 in
Grate area13.7 sq ft
Firebox area69.3 sq ft
Tube heating area753.7 sq ft
Evaporative heating area823 sq ft
Total heating area823 sq ft
Calculated Values
steam locomotive
secondary line
tank locomotive
last changed: 01/2022

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