Bavarian D XII

The Bavarian Class D XII steam locomotives were manufactured by the firm of Krauss from 1897 for the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn). Ninety six of them were procured for service on the stub lines running from Munich into the mountains, but in reality they were stationed in many large Bavarian locomotive depots (Bahnbetriebswerke or Bw). Two engines were transferred to the Palatinate Railway (Pfalzbahn) in 1916, the remaining 94 later joined the Deutsche Reichsbahn fleet and were incorporated as DRG Class 73.0-1 with operating numbers 73 031–124.

Bavarian D XII, Pt 2/5 N P 2.II (Palatinate) DRG Class 73.0–1
Number(s)	K.Bay.Sts.B. D XII: 2201–2296 Pt 2/5 N: 5205–5210, Pfalzbahn: 88(2nd)…95(2nd), 260–262, 264–284 Saar Railways: 6601–6605 DRG: P2.II: 73 001 – 73 028 D XII: 73 031 – 73 125 Pt 2/5 N: 73 131 – 73 139
Quantity	D XII: 96 P2.II: 31 Pt 2/5 N: 9 AL D33/T7/T5: 37 Total: 174
Manufacturer	Krauss (Munich) Maffei SACM (Grafenstaden)
Year(s) of manufacture	1897–1912
Retired	1948
Wheel arrangement	2-4-4T
Axle arrangement	1′B2′ n2t
Track gauge	1,435 mm (4 ft 8 1⁄2 in)
Length over buffers	11,850 or 11,928 mm (38 ft 10 1⁄2 in or 39 ft 1 1⁄2 in)
Service weight	68.8 or 67.5 t (67.7 or 66.4 long tons; 75.8 or 74.4 short tons)
Adhesive weight	28.8 or 30.0 t (28.3 or 29.5 long tons; 31.7 or 33.1 short tons)
Axle load	14.6 or 15.0 t (14.4 or 14.8 long tons; 16.1 or 16.5 short tons)
Top speed	90 km/h (56 mph)
Driving wheel diameter	1,640 mm (5 ft 4 5⁄8 in)
Leading wheel diameter	1,006 mm (3 ft 3 5⁄8 in)
Trailing wheel diameter	1,006 mm (3 ft 3 5⁄8 in)
No. of cylinders	Two
Cylinder bore	450 mm (17 11⁄16 in)
Piston stroke	560 mm (22 1⁄16 in)
Boiler Overpressure	12 or 13 kgf/cm2 (1,180 or 1,270 kPa; 171 or 185 lbf/in2)
Grate area	1.96 m2 (21.1 sq ft)
Evaporative heating area	104.63 m2 (1,126.2 sq ft)

The Palatinate Railway procured the almost identical Palatine P 2.II class in 31 examples during the years 1900 to 1903. 28 engines were taken over as 73 001–028 by the Deutsche Reichsbahn, the remaining three were handed over to the Saar Railway (Saarbahn).

Between 1903 and 1912, 37 engines went to the Imperial Railways in Alsace-Lorraine (Reichseisenbahnen in Elsaß-Lothringen) and were given the numbers T 5 6601–6637. One of these vehicles was taken over by the Deutsche Reichsbahn under operating number 73 125.

The Bavarian Pt 2/5 H built in 1906 as a one-off, had shown that the use of a superheater brought no clear gains due to the low coupled axle load. As a result, in 1907 nine similar machines with saturated steam operation were built, as the Bavarian Pt 2/5 N class. These engines were incorporated into the Deutsche Reichsbahn as numbers 73 131 to 73 139.

Most of the locomotives were retired by 1925; but several examples were still in the vehicle park until 1948.