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2-12-4T

Tank locomotive wheel arrangement

In Whyte notation for the classification of steam locomotives by wheel arrangement, a 2-12-4 is a locomotive with one pair of unpowered leading wheels, followed by six pairs of powered driving wheels, and two pairs of unpowered trailing wheels. While it would be possible to make a tender locomotive of this type, all locomotives of this wheel arrangement were tank engines.

Equivalent classifications

Other equivalent classifications are:

UIC classification: 1′F2′ (also known as German classification and Italian classification)
European classification: 1-6-2
French classification: 162

Bulgaria

There are only 20 standard gauge () engines with this wheel arrangement that were built for and ran in Europe: class 46 of the Bulgarian State Railways (BDŽ). They were ordered by BDŽ and built according to its specification by two different manufacturers: 12 engines by H. Cegielski in Poznań, Poland in 1931, and 8 by Berliner Maschinenbau (Schwarzkopf) in Berlin, Germany in 1943. Although there is a major difference between the two batches—the first 12 engines are type 1′F2′ h2Gt — tank-engine for freight service, two-cylinder system with simple steam expansion (Zwilling) with superheating, while the remaining 8 are 1′F2′ h3Gt — 3-cylinder (Drilling)—all were put into the same class 46 and numbered 46.01 – 46.12 and 46.13 – 46.20.

They were designed to haul heavy coal trains on mountainous lines with gradients of about 2.67% (1 in 35.7) and more, and they coped with this hard task very well. Bulgarian railwaymen gave them nickname "Mother Bear" because they looked fat, clumsy and compact. These engines appear to be the most powerful steam locomotives in Europe. Two of them (46.03 two-cylinder and 46.13 three-cylinder) are preserved. The two-cylinder 46.03 has been restored to working order and ran in steam in May 2015.

Technical specifications

BDZ 46.03, load test on 26th May 2015 (By Ivo Radoev).

BDZ 46.03 at Lakatnik railway station, 24th April 2016.

46.01 – 46.12	46.13 – 46.20
Locomotive No.
Gauge, mm	1,435
Type (UIC)	1′F2′ h2Gt
Type (BDŽ)	Тт 1-6-217
Builder	Cegielski
Year	1931
Steam pressure, kg/cm2	16
Superheater area, m2	83.91
Heating area, m2	224.07
Grate area, m2	4.87
Cylinders no. × dia. × stroke, mm	2 × 700 × 700
Driving wheels diameter, mm	1,340
Axleload, t	17
Adhesive weight, t	101.7
Total weight, t	149.1
Coal, t	10
Water, m3	18
Total length, m	18.205
Total height, m	4.28
Tractive effort, starting, kN	381
Tractive effort @ 20 km/h, kN	307.2
Max speed, km/h	65

References

"2-12-4 Locomotives in Bulgaria".

Info: Wikipedia Source

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