Lastspikemike Yes, thanks, I've actually previously book marked that extensively detailed description. Thanks. The disparity in pulling power for these steam locomotives has me pondering coefficients of friction on nickel silver... However, I noted an extensive thread on locomotive drawbar force as it may relate to the coefficient of friction of steel on steel as well as steel on sanded steel comparing prototype to HO. In light of the significant disagreements evident there I decided not to make my own contribution. The topic seems surprisingly controversial, given that the physics have been well understood for over 100 years. Interestingly, diesel models seem quite predictably uniform in their pulling power and roughly correspond to prototype patterns: bigger and heavier pull proportionately better. This is not the case for steam locomotive models which is frankly a bit weird.
Yes, thanks, I've actually previously book marked that extensively detailed description. Thanks.
The disparity in pulling power for these steam locomotives has me pondering coefficients of friction on nickel silver...
However, I noted an extensive thread on locomotive drawbar force as it may relate to the coefficient of friction of steel on steel as well as steel on sanded steel comparing prototype to HO.
In light of the significant disagreements evident there I decided not to make my own contribution. The topic seems surprisingly controversial, given that the physics have been well understood for over 100 years.
Interestingly, diesel models seem quite predictably uniform in their pulling power and roughly correspond to prototype patterns: bigger and heavier pull proportionately better. This is not the case for steam locomotive models which is frankly a bit weird.
It is not weird at all. Model steam locos, even with spring drivers suffer from a lack of even weight distribution on the drivers, as well as other traction losses on our sharp curves, etc. This problem increases with the number of driven axles.
The physics of the prototype does not scale down.
The flexibility of diesel trucks solves this problem.
Sheldon
Discussion of physics of model pulling power need to be in a properly-titled new thread -- they are only remotely, if at all, on-topic for the thread as titled and what may be a rich discussion will be missed by those not following the already-beaten-to-death nominal topic.
Overmod Discussion of physics of model pulling power need to be in a properly-titled new thread -- they are only remotely, if at all, on-topic for the thread as titled and what may be a rich discussion will be missed by those not following the already-beaten-to-death nominal topic.
I know you and I could write pages and pages, I just want to point out the obvious minimum explanation. I will let Mike explore the details on his own or with your help.
I have 19th Century houses to restore...
Sheldon.