The history of Bavarian locomotive Class BB II:
In 1899, Maffei built the first 3 locomotives, Class BB II (road number 2501-2503). Between 1900 and 1901, Maffei built another 22 locomotives (road number 2504-2525). Another 4 locomotives (road number 2526-2529) have been built in 1903 and last 2 locomotives (road number 2530 and 2531) have been built in 1908, also by Maffei.
When the Deutsche Reichsbahn (DRG) was formed, all 31 engines became Class 89.7 and were numbered 89 701 to 89 731.
Starting in 1882 after a number of laws had been repealed, the construction of local railroads rapidly took off. Locomotives were needed for this, which could master the steep grades and sharp curves, such as the line Kempten – Pfronten for example, with its grades of up to 1:40 and curves with a radius of only 180 meters or approximately 590 feet. For this reason it was initially decided not to build locomotives with four coupled axles in a rigid frame. Instead, the firm J. A. Maffei was awarded a contract to build a four-cylinder compound wet steam Mallet design locomotive. On this locomotive the rear fixed mainframe carried the two high-pressure cylinders; the low-pressure cylinders were mounted on the front, pivoting frame. Both the high pressure and low-pressure cylinders were equipped with Heusinger out-board mounted valve gear. The rear wheel sets in each group served at driving axles. At first these locomotives were equipped with a Hardy vacuum brake system, which was later replaced by a Westinghouse compressed air brake system. (www.minitrix.de)
Locomotive 98 727 can be seen at the "Railway Museum" in Darmstadt-Kranichstein, Germany.
Specifications:
Axle configuration: B’B n4v
Wheel diameter: 1006 mm
Overall length: 10010 mm
Wheelbase: 5200 mm
High pressure cylinder diameter: 310 mm
Low pressure cylinder diameter: 490 mm
Piston stroke: 530 mm
Grating area: 1.4 m2
Heating surface: 5.7 m2
Top speed: 45 km/h
Fully laden weight: 41.6 tons (2501-2525),
41.8 tons (2526-2531)
Water Supply: 4.3 m3
Coal supply: 1.5 tons
MINITRIX 12834
Bavarian Tank Locomotive Class BB II,
0-4-4-0T Mallet design.
Built in 1901, by Maffei.
Road number 2525
Manufacture period: 1990-1996
Overall length: 64 mm
