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How to use it
Enter the mass of the vehicle and any hauled mass, the speed, the gradient, the curve radius and the rolling resistance. Add the desired acceleration, the mass resting on the driven axles, the adhesion coefficient and the efficiency of the transmission. You get the tractive effort required, the margin against adhesion and the power.
Formulas used
Limits
Rolling resistance is a single input: at high speeds air resistance must be added. At starting the resistance is greater than when running. For hydrostatic transmissions and electric motors the torque curve and the continuous power must then be compared with the line profile.
FAQ
What adhesion should be considered?
On a dry rail values between 0.25 and 0.33 are used; with a wet or dirty rail it drops to 0.10–0.15. The check must be made in the worst condition expected in service.
What is the rotating mass factor?
It accounts for the inertia of wheels, axles, gears and rotors, which must be accelerated together with the vehicle. It is usually between 1.05 and 1.15 and rises with high-ratio gearboxes.