South African Class 25 4-8-4

South African Class 25 4-8-4
3511 at Hartswater, 24 April 1981
Type and origin
Power typeSteam
DesignerSouth African Railways
(L.C. Grubb)
Henschel & Son
BuilderHenschel & Son
North British Locomotive Company
Serial numberHenschel 28730
NBL 27312-27400
ModelClass 25
Build date1953
Total produced90
RebuilderSouth African Railways
Rebuild date1973-1980
Number rebuilt87 to Class 25NC
Specifications
Configuration:
  Whyte4-8-4
  UIC2′D2′h2
Driver2nd coupled axle
Gauge3 ft 6 in (1,067 mm) Cape gauge
Leading dia.30 in (762 mm)
Coupled dia.60 in (1,524 mm)
Trailing dia.30 in (762 mm)
Tender wheels34 in (864 mm)
Minimum curve275 ft (84 m)
Wheelbase95 ft 1+1116 in (28,999 mm)
  Engine38 ft (11,582 mm)
  Leading6 ft 10 in (2,083 mm)
  Coupled15 ft 9 in (4,801 mm)
  Trailing5 ft 6 in (1,676 mm)
  Tender45 ft 10 in (13,970 mm)
  Tender bogie10 ft (3,048 mm)
Length:
  Over couplers107 ft 6+116 in (32,768 mm)
Height13 ft (3,962 mm)
Frame typeCast
Axle load19 LT 6 cwt (19,610 kg)
  Leading21 LT 1 cwt (21,390 kg)
  1st coupled19 LT 4 cwt (19,510 kg)
  2nd coupled19 LT 5 cwt (19,560 kg)
  3rd coupled19 LT 6 cwt (19,610 kg)
  4th coupled19 LT 3 cwt (19,460 kg)
  Trailing22 LT 10 cwt (22,860 kg)
  Tender bogieBogie 1: 57 LT 4 cwt (58,120 kg)
Bogie 2: 56 LT 14 cwt (57,610 kg)
  Tender axle19 LT 1 cwt 2 qtr (19,380 kg)
Adhesive weight76 LT 18 cwt (78,130 kg)
Loco weight120 LT 9 cwt (122,400 kg)
Tender weight113 LT 18 cwt (115,700 kg)
Total weight234 LT 7 cwt (238,100 kg)
Tender typeCZ (3-axle bogies)
Fuel typeCoal
Fuel capacity19 LT (19.3 t)
Water cap.4,400 imp gal (20,000 L) main tank
600 imp gal (2,730 L) condensate
Firebox:
  TypeRound-top
  Grate area70 sq ft (6.5 m2)
Boiler:
  TypeDomeless
  Pitch9 ft 1+58 in (2,784 mm)
  Diameter6 ft 4+18 in (1,934 mm)
  Tube plates19 ft (5,791 mm)
  Small tubes158: 2+12 in (64 mm)
  Large tubes40: 5+12 in (140 mm)
Boiler pressure225 psi (1,551 kPa)
Safety valveRoss-pop
Heating surface:
  Firebox294 sq ft (27.3 m2)
  Tubes3,059 sq ft (284.2 m2)
  Arch tubes37 sq ft (3.4 m2)
  Total surface3,390 sq ft (315 m2)
Superheater:
  TypeMelesco
  Heating area630 sq ft (59 m2)
CylindersTwo
Cylinder size24 in (610 mm) bore
28 in (711 mm) stroke
Valve gearWalschaerts
Valve typePiston
Valve travel7+38 in (187 mm)
Loco brakeVacuum
CouplersAAR knuckle
Performance figures
Tractive effort45,360 lbf (201.8 kN) @ 75%
Career
OperatorsSouth African Railways
ClassClass 25
Number in class90
Numbers3451-3540
Official nameFrieda (3511)
NicknamesCondenser
Delivered1953-1954
First run1953
PreservedThree preserved, remainder scrapped

The South African Railways Class 25 4-8-4 of 1953 was a condensing steam locomotive.

Between 1953 and 1955, the South African Railways placed ninety Class 25 condensing steam locomotives with a 4-8-4 Northern type wheel arrangement in service. The Class 25NC which was placed in service at the same time was a non-condensing version of the Class 25 condenser.