Bavarian AA I

Bavarian AA I later P 2/4 DRG Class 36.8
Number(s)	1400 DRG 36 861
Quantity	1
Manufacturer	Krauss
Year(s) of manufacture	1896
Retired	1933
Wheel arrangement	4-2-2-2, later 4-4-0
Axle arrangement	2'aA1 n2v, later 2'B h2
Track gauge	1,435 mm (4 ft 8 1⁄2 in)
Length over buffers	16,570 mm
Service weight	51.7 t
Adhesive weight	29.8 t
Axle load	14.9 t
Top speed	90 km/h
Driving wheel diameter	1,870 mm
Leading wheel diameter	1,006 mm
No. of cylinders	2
Cylinder bore	490 mm
Piston stroke	610 mm
Boiler Overpressure	13 bar
Grate area	2.26 m2
Superheater area	26.85 m2
Evaporative heating area	94.60 m2
Tender	Bavarian 3 T 14.5
Water capacity	14.5 m3

The only AA I steam locomotive of the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn) was built by the firm of Krauss in 1896. It had been designed by chief mechanical engineer, Richard von Helmholtz, as a 4-2-2-2 tender locomotive. The engine was largely based on the Bavarian B XI, but the driving and running gear was modified. The second coupled axle was replaced by a fixed carrying axle, and a dolly axle (Vorspannachse) added between the bogie and driving axle. This could be lowered by a pressure cylinder and was driven by an auxiliary engine with two cylinders. Despite her high maintenance requirement, she was economical to run due to her low steam consumption. In 1907 she was rebuilt after an accident into a 2'B h2 locomotive and redesignated as a Class P 2/4. She was taken over by the Deutsche Reichsbahn and run under operating number 36 861. She was the last Bavarian 4-4-0 locomotive to be retired in 1933.

The engine was equipped with a Bavarian 3 T 14.5 tender.

See also

• Royal Bavarian State Railways
• List of Bavarian locomotives and railbuses

Literature

• Horst J. Obermayer (1990), "Dampflokomotiven" (in German), Deutsche Eisenbahnen (Stuttgart: Franckh-Kosmos Verlag): pp. 87, ISBN 3-89350-819-8 

Classes of Bavarian locomotive and railcars
Early locomotives	Adler Jupiter and Juno Vesta and Venus Vulkan and Mars Merkur and Diana A I A II A III A IV A V B I B II B III B IV B V B V (artic) C I C II
Passenger and express train locomotives	B VI B VII B VIII B IX (old) B IX B X B XI Zw B XI Vbd C V AA I S 2/5 (Vauclain) S 2/5 S 2/6 S 3/5 N S 3/5 H S 3/6 P 2/4 P 3/5 N P 3/5 H
Goods train locomotives	C II C III C IV Zw C IV Vbd C VI E I E I (Vauclain) BB I G 3/4 N G 3/4 H G 4/5 N G 4/5 H G 5/5
Tank locomotives	D I D II D II (old) D III D IV D V D IX D XII Pt 2/3 Pt 2/4 N Pt 2/4 H Pt 2/5 N Pt 2/5H Pt 3/6 Gt 2x4/4 R 3/3 R 4/4
Branch line locomotives	D VI D VII D VIII D X D XI BB II PtL 2/2 (Maffei) PtL 2/2 (Krauss) PtL 3/3 PtL 3/4 PtzL 3/4 GtL 4/4 (GtL 4/5 - DRG 98.10) (GtL 4/5 - DRG 98.11)
Narrow gauge locomotives	LE Pts 3/4 Gts 4/4 Gts 2x3/3
Electric locomotives	ES 1 EP 1 EP 2 EP 3 EP 4 EP 5 EG 1 EG 2 EG 3 (EG 4) (EG 5)
Railbuses	Krauss railmotor MCi MBCi MCCi MBCL MPL D4ieIT (D4ieIT variant - DRG ET 85)
Bavarian Ostbahn locomotives	A 1 – A 12 A 13 – A 24 A 1 – A 2 B 1 – B 66 B 67 – B 78 B 79 – B 90 B 91 – B 96 B 97 – B 109 C 1 – C 12 C 13 – C 64 D 1 – D 12 C 13 – C 14
Royal Bavarian State Railways