Benguela Railway 4-8-2 Locomotives in Angola

Class Details by Steve Llanso of Sweat House Media

Class 11th class (Locobase 2604)

Data from Brian Hollingsworth and Arthur Cook, The Great Book of Trains (New York: Portland House, 1987), pp. 188-189; and "South African Class 19D 4-8-2" in Wikipedia at [], last accessed 9 March 2023.. Works numbers were 26959-26964 in 1951.

Intended to haul 500-ton trains up 1.25% grades and around curves of a 300-ft (91.4 m) radius, these engines accomplished that goal on a low axle loading while burning eucalyptus logs as fuel. Tender capacity came to 650 cu ft (18.5 cu m); see Locobase 2860 for Peter Ball's discussion of eucalyptys as a fuel..Wikipedia states that the tenders were Type MX tank wagon types with cylindrical water tanks designed by Dr M M Loubser. Their shape led to their "Torpedo tender" nikname.

The design was based on the South African Railways 19C/19D Mountain (Locobases 2958 and 12790); Locobase data comes from the o designation shown in the Wikipedia table.

The high-pitched boiler was headed by a front end that included a Kyala-Chapelon (Kylchap) blast-pipe as well as spark-arresting gear. Other "luxuries" included power reverse, steam-operated fire doors, compensated springing to balance the load on the drivers and trailing axle. The class worked express mail trains on Atlantic coast runs and on the Silva Porto - Luau section.

Only a civil war could stop these engines from serving out long lives.

Principal Dimensions by Steve Llanso of Sweat House Media

Class11th class
Locobase ID2604
RailroadBenguela Railway
Number in Class6
Road Numbers401-406
Number Built6
BuilderNorth British
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)14.42 / 4.40
Engine Wheelbase (ft / m)32.25 / 9.83
Ratio of driving wheelbase to overall engine wheelbase 0.45
Overall Wheelbase (engine & tender) (ft / m)76.66 / 23.37
Axle Loading (Maximum Weight per Axle) (lbs / kg)31,248 / 14,174
Weight on Drivers (lbs / kg)123,984 / 56,238
Engine Weight (lbs / kg)178,304 / 80,877
Tender Loaded Weight (lbs / kg)164,304 / 74,527
Total Engine and Tender Weight (lbs / kg)342,608 / 155,404
Tender Water Capacity (gals / ML)6000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)650 / 2460.30
Minimum weight of rail (calculated) (lb/yd / kg/m)52 / 26
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)54 / 1372
Boiler Pressure (psi / kPa)204.50 / 14.10
High Pressure Cylinders (dia x stroke) (in / mm)21" x 26" / 533x660
Tractive Effort (lbs / kg)36,909 / 16741.66
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.36
Heating Ability
Tubes (number - dia) (in / mm)76 - 2.25" / 57
Flues (number - dia) (in / mm)24 - 5.5" / 140
Flue/Tube length (ft / m)20.17 / 6.15
Firebox Area (sq ft / m2)139 / 12.91
Grate Area (sq ft / m2)36 / 3.34
Evaporative Heating Surface (sq ft / m2)1839 / 170.85
Superheating Surface (sq ft / m2)390 / 36.23
Combined Heating Surface (sq ft / m2)2229 / 207.08
Evaporative Heating Surface/Cylinder Volume176.44
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7362
Same as above plus superheater percentage8614
Same as above but substitute firebox area for grate area33,258
Power L110,673
Power MT759.13

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