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.)

Tractive effort equation
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:-

Power equation
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 either English or Metric values
below to calculate TE and Power.
[If both English and Metric values are entered for the
same parameter, only the English value will be used.]
  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 Pounds
1 HP = 0.7457 kW
100 kPa = 14.5038 PSI		 1m = 39.370 ins = 3.2808 ft
1 km = 0.6214 miles
Tyically 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. Results to be used at you own risk.
Calculator provided for your personal use only.



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