# Tractive Effort & Power

#### (of Steam locomotives)

The Tractive Effort of a steam locomotive can be calculated from the formula:-
(Normal locomotives only. Not appliable to compound locomotives.) where:- K = Factor for losses (\$) P = Boiler pressure D = Cylinder bore S = Piston stroke W = Driving wheel diameter C = Number of cylinders

The Power output of a steam locomotive can be calculated from the formula:- where:- K = Factor for losses (\$) P = Boiler pressure (PSI) A = Area of piston (sq.ins) S = Piston stroke (ft) N = No. of power strokes per minute (#) (\$) Loss factor for cutoff, pressure drop in steam pipe, heat losses etc(approx 0.75 at 50% cutoff, 0.80 at 78% cutoff, 0.85 at 90% cutoff) (#) 2 per cylinder (for double acting pistons) x driving wheel RPM

Tractive Effort and Power Calculator
Enter input values in boxes below and click 'Calculate'
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 ↓ English Units ↓ Metric Units Pressure P: PSI kPa Bore D: ins m Stroke S: ins m Wheel dia W: ins m No.of cyl C: Loss factor K: Speed: mph kmph Tractive Effort: 0 lbs 0 kg Wheel RPM: 0 RPM Power output: 0 HP 0 kW Note: Simple formulas using +-*/() may be entered if desired, not just straight plain numbers.
 1kg = 2.2046 Pounds1 HP = 0.7457 kW100 kPa = 14.5038 PSI 1m = 39.370 ins = 3.2808 ft1 km = 0.6214 miles Typically use K=0.80 for saturated engines, K=0.85 for superheated engines. Note the accuracy of these calculations is not necessarily exact, and figures calculated here may vary from results published elswhere. They are calculated here from the formulas above to 3 or 4 significant digits only. Disclaimer: Results to be used at your own risk. Calculator provided for your personal use only.