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The reference for locomotives and railcars

Saxon VII T (Hartmann type)

German Reichsbahn class 9870

Germany 1882 43 produced
No. 1459 “Gustav Zeuner” on a Hartmann company photo PD

The Saxon class VII T included various two-axle local railway tank locomotives, most of which still came from the private railways. Later, the state railway ordered another 42 locomotives that were similar to the existing ones. Like other local railway locomotives, they were of simple design, since cheap maintenance was more important than high speeds or high tractive effort. Because the production batches were a total of twelve years apart, there were some changes from batch to batch. For example, the first locomotives took the live steam from a regulator on top of the boiler, but the later ones had a large steam dome. They had not yet a continuous air brake for the train.

There was also a one-off that had a longer wheelbase, larger wheels, was lighter and was 5 km/h faster. However, it was not built in series and retired in 1927. The Reichsbahn took over 29 of the 42 production locomotives in 1925 as 98 7051 to 98 7079. After the Second World War, all remaining ones came to the Reichsbahn of the GDR and the last ones were used there until 1967. One of them still exists today in its original color scheme.

Technical data

General

Property light variant heavy variant
Built 1882-1894
Manufacturers Hartmann
Wheel arrangement 0-4-0T (Four-coupled)
Gauge 1,435 mm (Standard gauge)

Dimensions and weights

Property light variant heavy variant
Length 7.88 m
Empty mass 19 t 20.7 t
Service mass 24.6 t 26.7 t
Adhesion mass 24.6 t 26.7 t
Axle load 12.3 t 13.4 t
Water capacity 2,900 l
Fuel capacity 0.9 t (coal)

Boiler

Property light variant heavy variant
Grate area 0.9 m²
Firebox surface 4.5 m²
Tube heating surface 39 m²
Evaporative heating surface 43.5 m²
Total heating surface 43.5 m²

Power plant

Property light variant heavy variant
Driver diameter 1,100 mm
Boiler pressure 12 bar
Expansion type simple expansion
Cylinders two, 355 x 530 mm

Power

Property light variant heavy variant
Power source steam
Estimated power 130 kW (177 PS)
Top speed 40 km/h
Starting effort 61.9 kN

Calculated values

Property light variant heavy variant
Factor of adhesion 1 : 3.90 1 : 4.23
Optimal speed 13 km/h
Power-to-weight ratio 5.3 kW/t 4.9 kW/t
Heating Surface Equivalent 66.0 m²
Cylinder volume/HSE 1 : 1,589.68
Adhesive weight/Total 1 : 1.00
Tractive force/Heating surface 1 : 29.74
Grate area/Heating surface 1 : 48.33
Firebox/Tube surface 1 : 8.67
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