1
$\begingroup$

Freight train is more efficient than truck due to lower rolling resistance. And I wonder which one has lower rolling resistance<>, small diameter or larger one or it doesn't not depend on diameter at all? Both are steel wheel on steel rail.

$\endgroup$
  • 4
    $\begingroup$ Have you tried searching for it? Since wikipedia has a page. $\endgroup$ – fibonatic Jul 10 '13 at 12:00
5
$\begingroup$

If you look at the Wikipeda article on rolling resistance that @fibonatic pointed out, you can find an equation for the coefficient of rolling friction:

$C_{rr}=\sqrt {\frac z d}$

There is another equation after it that is for steel on steel, but that also shows that C is proportional to $d^{-\frac 1 2}$. So from this, you can easily see that a smaller diameter will have a higher C, and thus a higher resistance. A freight train will have a larger diameter than a truck, meaning less resistance, thus being more efficient.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.