# Calculating Tractive Effort At Speeds

1. Mar 5, 2015

### alphareign

How does one calculate the tractive effort of a locomotive at various speeds? Is there a formula for this?

2. Mar 5, 2015

### jack action

The tractive effort ($F_t$) is simply the power available at the wheels ($P$) divided by the speed of the locomotive ($v$):

$$F_t = \frac{P}{v}$$​

But, no matter how much power there is at the wheels, it cannot exceed the friction force between the wheels and the rails (otherwise the wheels are spinning):

$$F_t = \mu N$$​

Where $\mu$ is the coefficient of friction and $N$ is the normal force acting on the wheels.

3. Mar 5, 2015

### alphareign

Thank you so much.

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