Bengal North 4-4-0 Locomotives in India

Class Details by Steve Llanso of Sweat House Media

Class O (Locobase 10180)

Data from "Locomotives for the Indian Metre Gauge Rys", The Locomotive Magazine, Vol VI (February 1901), p. 50.

The LM author tells us that the O-class passenger engines shown here and the F-class goods engines described in Locobase 10181 were standard metre-gauge locomotives for the Indian State Railways as well as many other private lines. O-class engines were built from 1883 to 1912; this variant thus falls in the middle of the period.

To allow the largest possible grate within the confines of a narrow loading gauge, the plate frames lay outside of the wheels. Such placement in turn required the use of fly cranks to take the connecting rod's (main rod's) thrust and these also acted as the journals within the axle boxes. Boilers could be round-top or Belpaire; the locomotive described in the specs had a Belpaire firebox.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID10180
RailroadBengal North
Number in Class297
Road Numbers
Number Built297
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)6 / 1.83
Engine Wheelbase (ft / m)12.17 / 3.71
Ratio of driving wheelbase to overall engine wheelbase 0.49
Overall Wheelbase (engine & tender) (ft / m)39.37 / 12
Axle Loading (Maximum Weight per Axle) (lbs / kg)18,256 / 8281
Weight on Drivers (lbs / kg)36,428 / 16,523
Engine Weight (lbs / kg)53,592 / 24,309
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)1200 / 4.55
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)30 / 15
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)53 / 1346
Boiler Pressure (psi / kPa)140 / 9.70
High Pressure Cylinders (dia x stroke) (in / mm)14" x 20" / 356x508
Tractive Effort (lbs / kg)8802 / 3992.52
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.14
Heating Ability
Tubes (number - dia) (in / mm)122 - 1.625" / 41
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)56.50 / 5.25
Grate Area (sq ft / m2)10.58 / 0.98
Evaporative Heating Surface (sq ft / m2)753 / 69.98
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)753 / 69.98
Evaporative Heating Surface/Cylinder Volume211.32
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1481
Same as above plus superheater percentage1481
Same as above but substitute firebox area for grate area7910
Power L13594
Power MT435.02

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Wes Barris