How does rolling resistance of rail wheel depend on diameter?

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Discussion Overview

The discussion centers on the relationship between the diameter of rail wheels and their rolling resistance, particularly in the context of freight trains compared to trucks. Participants explore whether larger or smaller diameters result in lower rolling resistance and the underlying mechanics involved.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that larger wheels may have lower rolling resistance, questioning if this is influenced by diameter at all.
  • Another participant proposes that larger wheels provide a mechanical advantage due to increased torque, although this claim is later challenged.
  • A different viewpoint indicates that larger wheels may distribute pressure more effectively, leading to less ground deformation and thus lower rolling resistance.
  • Several participants reference external sources, including Wikipedia, to support their claims, but there is confusion regarding the validity of specific notes within those sources.

Areas of Agreement / Disagreement

Participants express differing opinions on the impact of wheel diameter on rolling resistance, with no consensus reached on whether larger or smaller diameters are more efficient.

Contextual Notes

There are references to external sources that may not fully support the claims made, leading to uncertainty about the reliability of the information discussed. The discussion also highlights the complexity of the relationship between wheel diameter and rolling resistance, with various factors potentially influencing the outcome.

lemd
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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.
 
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a larger wheel has a larger torque mechanical advantage to overcome resistance
 
Thanks,

From some source, it seems larger wheel has lower rolling resistance, but explained by larger torque seems to be not really true because torque can be change by gear ratio. I think larger wheel will spread it pressure better and so deform ground less and so on, less rolling resistance.
 
tiny-tim said:
note #33 in that link does not confirm this :confused:

lol good eye, I would have missed that notation,
 

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