| DR Class 99.77–79 |
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99 789 on the Fichtelbergbahn in January 2013 |
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| Specifications |
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Configuration:
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| • Whyte | 2-10-2T |
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| • UIC | 1′E1′ h2t |
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| • German | K 57.9 |
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| Gauge | 750 mm (2 ft 5+1⁄2 in) |
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| Leading dia. | 550 mm (1 ft 9+5⁄8 in) |
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| Driver dia. | 800 mm (2 ft 7+1⁄2 in) |
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| Trailing dia. | 550 mm (1 ft 9+5⁄8 in) |
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| Wheelbase: | |
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• Axle spacing
(Asymmetrical) | - 1,800 mm (5 ft 10+7⁄8 in) +
- 1,000 mm (3 ft 3+3⁄8 in) +
- 1,000 mm (3 ft 3+3⁄8 in) +
- 1,000 mm (3 ft 3+3⁄8 in) +
- 1,000 mm (3 ft 3+3⁄8 in) +
- 1,800 mm (5 ft 10+7⁄8 in) =
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| • Engine | 7,600 mm (24 ft 11+1⁄4 in) |
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Length:
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| • Over couplers | 11,300 mm (37 ft 7⁄8 in) |
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| • Over headstocks | 10,000 mm (32 ft 9+3⁄4 in) |
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| Height | 3,550 mm (11 ft 7+3⁄4 in) |
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| Axle load | 8.6 t (8.5 long tons; 9.5 short tons) |
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| Adhesive weight | 42.8 t (42.1 long tons; 47.2 short tons) |
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| Empty weight | 41.5 t (40.8 long tons; 45.7 short tons) |
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| Service weight | 55.0 t (54.1 long tons; 60.6 short tons) |
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| Fuel type | Coal |
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| Fuel capacity | 3.6 t (3.5 long tons; 4.0 short tons) |
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| Water cap. | 5.8 m3 (1,280 imp gal; 1,530 US gal) |
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| Firebox: | |
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| • Grate area | 2.57 m2 (27.7 sq ft) |
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Boiler:
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| • Pitch | 2,100 mm (6 ft 10+5⁄8 in) |
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| • Tube plates | 3,200 mm (10 ft 6 in) |
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| • Small tubes | 44.5 mm (1+3⁄4 in), 92 off |
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| • Large tubes | 121 mm (4+3⁄4 in), 28 off |
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| Boiler pressure | 14 bar (14.3 kgf/cm2; 203 psi) |
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| Heating surface: | |
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| • Firebox | 8.5 m2 (91 sq ft) |
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| • Tubes | 36.6 m2 (394 sq ft) |
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| • Flues | 31.8 m2 (342 sq ft) |
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| • Total surface | 76.9 m2 (828 sq ft) |
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Superheater:
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| • Heating area | 28.8 m2 (310 sq ft) |
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| Cylinders | Two, outside |
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| Cylinder size | 450 mm × 400 mm (17+11⁄16 in × 15+3⁄4 in) |
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| Valve gear | Heusinger (Walschaerts) |
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| Train brakes | Hardy vacuum brake,
Heberlein brake no longer provided |
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| Performance figures |
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| Maximum speed | 30 km/h (19 mph) |
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| Indicated power | 600 PS (441 kW; 592 hp) |
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| Tractive effort | 83.35 kN (8,500 kp; 18,740 lbf) |
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The steam locomotives of DR Class 99.77–79 were ordered by the Deutsche Reichsbahn in East Germany after the Second World War. They were narrow gauge locomotives with a 750 mm rail gauge and were built for the narrow gauge lines in Saxony. The locomotives were largely identical to the DRG Class 99.73–76 standard locomotives (Einheitslokomotiven) built in the 1930s. To differentiate them from their predecessors they were described as Neubaulokomotiven or newly designed engines.
