OECM 2-8-2 Locomotives in Morocco

Class Details by Steve Llanso of Sweat House Media

Class 141 A1 (Locobase 15602)

Data from "New 2-8-2 Type Locomotives for Moroccan Railways", Railway Gazette (26 August 1932), p. 257. See also Jacques Gandini, "Les locomotives a vapeur", Les Chemins de Fer de Maroc website at [], last accessed 14 November 2013.

The great success of the Etat Mikado design that appeared in 1921 (Locobase 15577). When the Moroccan Railway sought a powerful locomotive, they supplied the Polish builder Chrzanow with plans and asked for duplicates. While keeping the Belpaire firebox, cylinder size, and driver diameters, Chrzanow decreased the number of small tubes and increased the diameter of the flues holding a new superheater design. As can be seen, the larger superheater provided an impressive percentage of total heating surface area.

Piston valve diameters measured 350 mm (13.75 in) and offered a 156 mm (6.17 in) maximum stroke. A Dabeg "feed-heating" pump (probably best thought of as an exhaust injector) added to the boiler's readiness to steam and a Kylchap blast pipe enhanced exhaust performance.

(NB: As per Continental practice, evaporative heating surface was calculated from the fire side (interior diameter). Using the 50 mm/1.97 in tubes and 140 mm/5.51 in diameters, tube and flue heating surface area amounted to 173.3 sq m/1,865 sq ft. With the firebox area, evaporative heating surface area was 188.4 sq m/2,027 sq ft. Locobase uses the external diameter to simplify comparisons with British- and American-influenced locomotives.)

Principal Dimensions by Steve Llanso of Middle Run Media

Class141 A1
Locobase ID15602
Number in Class12
Road Numbers141 A1 a 141 A12
Number Built12
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)11.81 / 3.60
Engine Wheelbase (ft / m)35.83 / 10.92
Ratio of driving wheelbase to overall engine wheelbase 0.33
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)159,835 / 72,500
Engine Weight (lbs / kg)205,030 / 93,000
Tender Loaded Weight (lbs / kg)119,049 / 54,000
Total Engine and Tender Weight (lbs / kg)324,079 / 147,000
Tender Water Capacity (gals / ML)5808 / 22
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 6.60 / 6
Minimum weight of rail (calculated) (lb/yd / kg/m)67 / 33.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)65 / 1650
Boiler Pressure (psi / kPa)174 / 12
High Pressure Cylinders (dia x stroke) (in / mm)24.41" x 27.56" / 620x700
Tractive Effort (lbs / kg)37,365 / 16948.50
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.28
Heating Ability
Tubes (number - dia) (in / mm)123 - 2.165" / 55
Flues (number - dia) (in / mm)24 - 5.827" / 148
Flue/Tube length (ft / m)19.03 / 5.80
Firebox Area (sq ft / m2)162.54 / 15.10
Grate Area (sq ft / m2)40.90 / 3.80
Evaporative Heating Surface (sq ft / m2)2186 / 203.10
Superheating Surface (sq ft / m2)704 / 65.40
Combined Heating Surface (sq ft / m2)2890 / 268.50
Evaporative Heating Surface/Cylinder Volume146.44
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7117
Same as above plus superheater percentage8825
Same as above but substitute firebox area for grate area35,070
Power L111,787
Power MT650.32

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