DR Class 99.23-24

The engines of DR Class 99.23 are metre gauge steam locomotives, that were procured by the Deutsche Reichsbahn (DR) in East Germany from 1954 to 1956. When they entered service they had operating numbers 99 231–99 247. Today they are numbered 99 7231–99 7247.

DR Class 99.23-24
99 7243
Number(s)99 231 – 99 247
from 1970: 99 7231 – 99 7247
Quantity17
ManufacturerVEB Lokomotivbau "Karl Marx" Babelsberg
Year(s) of manufacture1954–1956
Wheel arrangement2-10-2T
Axle arrangement1′E1′ h2t
TypeK 57.10
Track gauge1,000 mm (3 ft 3 3⁄8 in) metre gauge
Length over buffers12,500 mm (41 ft 1⁄4 in)
Height3,650 mm (11 ft 11 11⁄16 in)
Width2,645 mm (8 ft 8 1⁄8 in)
Wheelbase4,800 mm (15 ft 9 in)
Overall wheelbase8,700 mm (342 1⁄2 in)
Empty weight47.5 tonnes (46.7 long tons; 52.4 short tons)
Service weight60.5 tonnes (59.5 long tons; 66.7 short tons)
Adhesive weight47.5 tonnes (46.7 long tons; 52.4 short tons)
Axle load9.5 tonnes (9.3 long tons; 10.5 short tons)
Top speed40 km/h (25 mph)
Indicated Power515 kW (700 PS; 691 hp)
Starting tractive effort102.9 kN (23,100 lbf)
Driving wheel diameter1,000 mm (3 ft 3 3⁄8 in)
Carrying wheel diameter550 mm (1 ft 9 5⁄8 in)
Valve gearHeusinger with Kuhn slides
No. of cylinders2
Cylinder bore500 mm (19.69 in)
Piston stroke500 mm (19.69 in)
Boiler Overpressure14 bar (1.40 MPa; 203 psi)}
No. of heating tubes114
No. of smoke tubes32
Grate area2.8 m2 (30 sq ft)
Radiative heating area10.4 m2 (112 sq ft)
Superheater area30 m2 (320 sq ft)
Evaporative heating area95.5 m2 (1,028 sq ft)
Water capacity8 m3 (280 cu ft) or 8,000 litres (1,800 imp gal; 2,100 US gal)
FuelCoal: 4 tonnes (3.9 long tons; 4.4 short tons)
BrakesKe G-P mZ
Locomotive brakesHardy vacuum-controlled compressed air brake with Knorr auxiliary brake, converted to direct-release compressed air brake with KNORR EMV10 control valve and auxiliary brake
Train brakesHardy vacuum brake, converted to Knorr compressed air brake
CouplersEqualising lever couplers (de:Balancierhebelkupplung); in Eisfeld: Janney

History

Between 1954 and 1956 a total of 17 locomotives were bought by the DR for the railways of the Harzquerbahn and Brockenbahn and for the line from Eisfeld to Schönbrunn. They replaced much of the very old fleet. The first seven units (99 231 to 99 237) were originally equipped with two Krauss-Helmholtz bogies. Due to problems with curve running the engines in the second series were given Beugniot levers between the first and second coupled axles in addition to the Krauss-Helmholtz bogies.[1] (according to other sources also a Schwartzkopff-Eckhardt II bogie [2][3][4][5]). The locomotives of the first series were subsequently modified with Beugniot levers, some in the early 1960s, others in 1973/74 (on the Harz lines). The thinner wheel flanges of the driving wheels were completely removed later in order to achieve better curve running. Certainly the engines in the second series did not have a rigid wheelbase.[2]

The drive was applied to the third coupled axle, the locomotives had Heusinger valve gear with unsprung Müller balanced slide valves and, later, Trofimoff valves.

These Neubaulokomotiven were a fully welded evolutionary development of the standard locomotives (Einheitsloks) of the DRG Class 99.22. In contrast to those, the 99.23-24s had mixer-preheaters and plate frames. However, the latter caused maintenance difficulties from the outset due to cracks and distortion. To date five locomotives (the present-day 99 7232, 7240, 7245, 7239, 7236) were equipped from 2004 onwards with a new, redesigned plate frames and new, welded, steam cylinders. More should follow. All the engines still exist and are based in the Harz; some however are no longer working.

The engines were converted between 1977 and 1983 to primary oil-firing and are the most powerful German narrow gauge steam locomotives ever to have been built. They are primarily used on the line up to the Brocken from Wernigerode.

Their operating numbers changed from 99 231 et seq to 99 7231 et seq on the introduction of computerised numbers in 1970 and then again to 99 0231 et seq on conversion to oil-firing. The computer numbers are still valid, because the HSB retains those allocated in the 1970 DR renumbering scheme.

The vehicles can carry 4.0 tonnes of coal and 8.0 m3 of water.

Locomotives
  • 99 7231: out of service
  • 99 7232: working, new frame
  • 99 7233: out of service
  • 99 7234: working
  • 99 7235: working
  • 99 7236: working, new frame
  • 99 7237: working
  • 99 7238: out of service
  • 99 7239: working, new frame
  • 99 7240: working, new frame
  • 99 7241: working
  • 99 7242: working
  • 99 7243: working
  • 99 7244: out of service
  • 99 7245: working, new frame
  • 99 7246: out of service
  • 99 7247: working
  • 99 7232
  • 99 7234
  • 99 7237

Sources and references
  1. Weisbrod/Wiegard/Müller/Petznik: Deutsches Lok-Archiv: Dampflokomtiven 4. Baureihe 99, Transpress Berlin 1995, ISBN 3-344-70903-8
  2. EK-Themen 18, Brockenlok 99.22, Eisenbahn-Kurier, Freiburg 1995
  3. Obermayer: Taschenbuch Deutsche Schmalspur-Dampflokomotiven. Franckh'sche Verlagshandlung, Stuttgart 1971, ISBN 3-440-03818-1
  4. Kühne. Alles über DDR-Dampfloks, Transpress, Stuttgart 2008, ISBN 978-3-613-71335-2
  5. Website of the Freundeskreises Selketalbahn (see below)

Literature
  • Weisbrod, Manfred; Wiegard, Hans; Müller, Hans; Petznick, Wolfgang. Deutsches Lok-Archiv: Dampflokomotiven 4 (Baureihe 99), Transpress, Berlin,ISBN 3-344-70903-8, 1995, pp 53–57.
  • Vetter, Klaus J. Das große Handbuch deutscher Lokomotiven, Bruckmann, München, ISBN 3-7654-3764-6, 2001, pp 191–192.
  • Obermayer, Horst J. Taschenbuch Deutsche Schmalspur-Dampflokomotiven, Franckh'sche Verlagshandlung, Stuttgart, ISBN 3-440-03818-1, 1971, pp. 60–61.

See also
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