Power output (Loco)

Oct 22, 2004 2 Replies

Hi I am building a 5 gauge steam loco Just wondering how can you work the power output in BHP??? that the engine will deliver.


Someone should be able to post a formula for the tractive effort supplied by a steam engine, for a given piston diameter, boiler pressure, and wheel diameter. Then you've got to decide what speed you can maintain that effort up to.

But that assumes you don't get wheel slip. I believe there's a rule of thumb that maximum traction is 25% of the weight on the driven wheels.

Or read this article relating output to the capacity of the boiler to burn fuel:

formatting link
Once you've got your engine, you can do practical measurements. You could measure the drawbar pull with a spring balance in the coupling and time yourself over a measured distance? If necessary, apply brakes to the train to maintain a steady load. (Use a backup chain for safety)

Looking at the performance of battery locos with 1HP motors, you may be surprised how little power is required.

Wilfrid Underwood

Try this:

formatting link
Wilfrid Underwood

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required