2-12-4

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.

Other equivalent classifications are:

Bulgaria

There are only 20 standard gauge (1,435 mm (4 ft 8 1⁄2 in)) engines with this wheel arrangement that were built for and ran in Europe - class 46 of Bulgarian State Railways (BDZ). They were ordered by BDZ and built according to its specification by two different manufacturers: 12 engines by Cegielski in Poznań (Poland) in 1931, and 8 by 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, 2-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 28‰ (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 of Zwillings and 46.13 of Drillings) are preserved.

Technical specifications:

Locomotive No. 46.01 - 46.12 46.13 - 46.20
Gauge, mm 1435 1435
Type (UIC) 1'F2'h2Gt 1'F2'h3Gt
Type (BDZ) TT1-6-217 TT1-6-218
Builder Cegielski Schwarzkopf
Year 1931 1943
Steam pressure, kg/cm2 16 16
Superheater area, m2 83.91 80
Heating area, m2 224.07 223.6
Grate area, m2 4.87 4.87
Cylinders no. x dia. x stroke, mm 2 x 700 x 700 3 x 550 x 650
Driving wheels diameter, mm 1340 1340
Axleload, t 17 18
Adhesive weight, t 101.7 108
Total weight, t 149.1 155.8
Coal, t 10 10
Water, m3 18 18
Total length, mm 18205 18155
Total height, mm 4280 4345
Tractive effort, starting, kN 381 360
Tractive effort @ 20 km/h, kN 307.2 264.1
Max speed, km/h 65 65
Single engine types
0-2-2 • 0-2-4 • 2-2-0 • 2-2-2 • 2-2-4 • 4-2-0 • 4-2-2 • 4-2-4 • 6-2-0
0-3-0
0-4-0 • 0-4-2 • 0-4-4 • 2-4-0 • 2-4-2 • 2-4-4 • 2-4-6 • 4-4-0 • 4-4-2 • 4-4-4 • 4-4-6
0-6-0 • 0-6-2 • 0-6-4 • 2-6-0 • 2-6-2 • 2-6-4 • 2-6-6 • 4-6-0 • 4-6-2 • 4-6-4
0-8-0 • 0-8-2 • 0-8-4 • 2-8-0 • 2-8-2 • 2-8-4 • 2-8-6 • 4-8-0 • 4-8-2 • 4-8-4 • 4-8-6 • 6-8-6
0-10-0 • 0-10-2 • 2-10-0 • 2-10-2 • 2-10-4 • 4-10-0 • 4-10-2
0-12-0 • 2-12-0 • 2-12-2 • 2-12-4 • 4-12-2 •
4-14-4
Divided drive and
Duplex engine types
2-(2-2)-0 • 2-(2-2)-2 • 2-2-(4-0) • 4-2-2-0 •
2-4-6-2 • 4-4-4-4 • 6-4-4-6 • 4-4-6-4 •
4-6-4-4
Articulated locomotives
Garratt and Meyer types
Articulated locomotives
Fairlie and Mallet types
(includes Triplex types).
0-4-4-0 • 0-4-4-2 • 2-4-4-0 • 2-4-4-2
0-6-6-0 • 2-6-6-0 • 2-6-6-2 • 2-6-6-4 • 2-6-6-6 • 2-6-8-0 • 4-6-6-2 • 4-6-6-4
0-8-6-0 • 0-8-8-0 • 2-8-8-0 • 2-8-8-2 • 2-8-8-4 • 4-8-8-2 • 4-8-8-4
2-10-10-2 • 2-8-8-8-2 • 2-8-8-8-4
Articulated locomotives
Engerth types
0-4-4 • 0-4-6
2-6-2 • 0-6-4 • 0-6-4-0
0-8-4 • 0-8-6