Tractive Effort Calculation for 4 Cylinder Compound 'Argentina'

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Note: The figures presented below have been rounded to 3 decimal points to simplify presentation so may not give the precise answers shown when checking the figures. However these answers are valid when working to a higher number of decimal places.

The following lines of calculation as based on the formulæ given in 1936 by E.A.Phillipson in the book "Steam Locomotive Design: Data and Formulæ."

The formula used, which applies ONLY to 4 cylinder compound steam locomotives states:

Tractive Effort = 2(DxD)Sp / (R+1)W

Where:

D = Low Pressure Cylinder Diameter.
S= Low Pressure Cylinder Stroke.
p = Receiver Pressure.*
R = Area of High Pressure Piston / Area of Low Pressure Piston.
W = Diameter of Driven Wheels.

*In addition it is stated that p shall be calculated thus:

p = P / (R+1)

Where:

P: Boiler Pressure multiplied by 0.8

Therefore in the case of 'Argentina' the figures, calculated in Imperial measures, are:

D = 22.835"
S = 22.047"

DxD = 521.418"
High Pressure Cylinder Area squared = 200.879

R = 521.418 / 200.879
   = 0.385

p = (285x0.8) / (0.385+1)
   = 228 / 1.385
   = 164.590psi

TE = (2x521.418x22.047x164.590) / 1.385x50
     = 3784199.078 / 69.262
     = 54635.384lbs

Conversion from Imperial to Metric:

1lbs force = 0.004 kN

54635.384x0.004 = 243kN

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