gregc peahrens: when the force on the light wheel gets to it's tractive effort limit, by it will start to slip. At that point it's tractive effort will go down (below max) as I understand it because it's slipping coefficient of friction is lower(?). greg: i believe once the wheel/axle slips, the force of the piston is redistributed on the remaining wheels. In your 0-4-0 case, it doubles. the force of the piston has to be balanced by frictional forces.
peahrens: when the force on the light wheel gets to it's tractive effort limit, by it will start to slip. At that point it's tractive effort will go down (below max) as I understand it because it's slipping coefficient of friction is lower(?).
greg: i believe once the wheel/axle slips, the force of the piston is redistributed on the remaining wheels. In your 0-4-0 case, it doubles. the force of the piston has to be balanced by frictional forces.
Thanks, Greg,
I get it now. I was very much overlooking the incoming (piston) force aspect as well as the dynamic cycle aspects of the rods to the wheels. I can see how exceeding the first wheel adhesion force starts it spinning and that the other (0-4-0 case) wheel's max adhesion ability cannot handle the whole incoming force, so it all starts spinning.
And that the balancing therefore is important for a steam loco.
I enjoyed the learning process, thanks to you and others.
Paul
Modeling HO with a transition era UP bent
yes. threads like these are interesting and educational.
greg - Philadelphia & Reading / Reading
doctorwayne Since I won't use traction tires, I solve the problem of insufficient tractive effort by adding more locomotives....works well, even using DC control. Wayne
Wayne
Wayne,
At the risk of generating a potentially major side issue, may I ask why you avoid traction tires? Is it simply one of on-going loco maintence that is a pain in the neck, or something else? And as long as I've just threatened this thread, why not juice it a bit more by asking what would happen if I chucked the tires on my MT-4s? I'll be glad to post the matter as a separate subject if it gets in the way of this one.
John
No major side issue, John, it just seems that traction tires are too artificial for my tastes. I had a steam locomotive some time ago that had traction tires and it was simply a lousy-running locomotive. I realise that such things are much improved, but they simply don't interest me as much as trying to improve the pulling power in other ways. In normal operations, my longest train would likely be 20 cars or less, and many might be much shorter. Most operations, when I get around to that stage of the game, will involve a loco going from town to town, dropping-off or picking-up cars, and perhaps simply re-spotting one or two as needed. Then it's off to the next town.The through trains will run mostly between staging yards, stopping only for water, and they're the ones more likely to be longer and to use more than one locomotive.
As for removing traction tires from your loco, do you have replacement drivers without the grooves? It would be interesting to compare the tractive effort with or without them, but, regardless of the results, I'm unlikely to become a convert.
gmpullmanThere was a controversial issue between labor, management and the ICC regarding older, non-stoker, locomotives having to be retrofitted with stokers based on their weight on drivers.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
https://www.fronz.org.nz/sites/default/files/technical-papers/B31201_Weighing_of_Locomotives.pdf
pg 5, 1(a) notes one purpose for ensuring "weight is correctly distributed" is to "reduce wheelslip".