Mecklenburg T 4

The Mecklenburg T 4 was a German steam locomotive built for the Grand Duchy of Mecklenburg Friedrich-Franz Railway as a goods train tank locomotive with a leading axle and three coupled axles (2-6-0T). In 1925 it was incorporated in the renumbering plan of the Deutsche Reichsbahn as DRG Class 91.19.

Mecklenburg T 4 DRG Class 91.19
MFFE 714 in a works photograph.
Number(s)	MFFE: 701–750 DRG 91 1901–1950 DR 91 6401–6404
Quantity	50+6
Manufacturer	Henschel & Sohn Orenstein & Koppel
Year(s) of manufacture	1907–1922
Retired	1935–1970
Wheel arrangement	2-6-0T
Axle arrangement	1′C n2t
Type	Gt 34.11, Gt 34.12
Track gauge	1,435 mm (4 ft 8 1⁄2 in)
Length over buffers	10,375 mm (34 ft 1⁄2 in)
Height	4,150 mm (13 ft 7 3⁄8 in)
Empty weight	35.68–37.40 t (35.12–36.81 long tons; 39.33–41.23 short tons)
Service weight	45.24–46.8 t (44.53–46.06 long tons; 49.87–51.59 short tons)
Adhesive weight	35.6–36.6 t (35.0–36.0 long tons; 39.2–40.3 short tons)
Axle load	11.8–12.2 t (11.6–12.0 long tons; 13.0–13.4 short tons)
Top speed	45–50 km/h (28–31 mph)
Indicated Power	470 PS (346 kW; 464 hp)
Coupled wheel diameter	1,150 or 1,200 mm (3 ft 9 1⁄4 in or 3 ft 11 1⁄4 in)
Leading wheel diameter	800 mm (2 ft 7 1⁄2 in)
Valve gear	Walschaerts (Heusinger)
No. of cylinders	Two
Cylinder bore	410 mm (16 1⁄8 in)
Piston stroke	580 mm (22 13⁄16 in)
Boiler Overpressure	12 kgf/cm2 (1,180 kPa; 171 lbf/in2)
No. of heating tubes	173
Heating tube length	3,700 mm (12 ft 1 3⁄4 in)
Grate area	1.60 m2 (17.2 sq ft)
Radiative heating area	7.41 m2 (79.8 sq ft)
Tube heating area	92.5 m2 (996 sq ft)
Evaporative heating area	99.90 m2 (1,075.3 sq ft)
Water capacity	4.3–5.6 m3 (950–1,230 imp gal; 1,100–1,500 US gal)
Fuel	1,500 kg (3,300 lb) coal

At the beginning of the 20th century much more powerful locomotives were needed for branch line operations, but the tried and trusted Prussian engines could not be used because the T 9 family was already clearly too heavy. As a result, Henschel-Werke was given an order for what became the Mecklenburg T 4, one of the few locomotive classes to be developed by Mecklenburg itself. Contrary to what is often stated in the literature, these engines had a Krauss-Helmholtz bogie (just like the Prussian T 9.3). The Reichsbahn took over all 50 vehicles. Because the Mecklenburg routes were reinforced, the first locomotives became superfluous as early as the 1930s. Of the 38 locomotives left after the Second World War, two were taken over by the PKP in Poland, four came into the hands of the Deutsche Bundesbahn (DB), 15 had to be given up as reparations and two were retired as a result of serious damage, leaving just 13 with the Deutsche Reichsbahn (DR) in East Germany, of which two in the early 1950s ran in Saxony (for example between Niederschlema and Schneeberg, because damage by the uranium mines meant that only very light vehicles could be employed; eventually even that was no longer possible). The DB retired its locomotives by 1950 due to their low numbers, but continued to use them for a long time as industrial locos in repair shops. In 1949, the DR took over four of the six locomotives built in 1919/1920 for private lines by Henschel and gave them the numbers 91 6401–6404. The last of these engines were withdrawn from service in 1970.