Grades and Curves

[Anonymous]

Has anyone done any recent research into what locos (and how many) will draw how many cars up what grades/ round what curves. We rarely use spirals here (UK) but I want to use three levels of staging tracks. I can get about 20' of clear tracks between ladders of switches... I reckon that's approximately 30 50' cars... Anyone know whether two Kato SD 40-2s [for example ] will pull this comfortably up 15' of 1:60 (About 1.5% I think???) curve could be 4' or 5' radius... (don't have a clue what offset that is). May also run 3 GP35s for same load... and similar.

Does anyone have any information on power supply / control?

DCC... I'm old fashioned so far but wonder whether DCC has any differences when putting on loads.

[markpierce]

According to a 1917 textbook on railroad engineering, compensating grades (to allow for the increased resistance experienced) on curves varied between 0.03 percent to 0.05 percent for each degree of curve. The primary factor was the proportion of the train occupying the curve, and of course, the sharpness of the curve. The grade was reduced on the curve based on the appropriate calculation. You will need to convert radius measured in inches to prototype feet and convert this to degree of angle. Of course, it is unlikely the physical forces involved with the prototype match those of models. Has anyone experimented to get a formula applicable to a particular modeling scale?

[Anonymous]

Thanks

I think that the hugely different curves we use will negate those real life figures.

I suspect that it will come down to empirical evidence.

When I get the far I will try to post what I can haul up what with what... but has no-one come up with any evidence.

[Anonymous]

Sounds like you may need to do a mockup of the trck length and curve and try varying grades to develop your own evidence. There are so many variables from the proto type to our scale sizes that do not give you the necessary factors to determine the practical operation of 30 car trains with spectic locomotives. Everyone will be guessing at the actual pulling strength of the engines and the rolling resistance of the cars as affected by the curve and grade variables.
Will

[johncolley]

Try it and see if it can do it! If it can't, you add a helper district for more operational challenges! Another pair of units 2/3 of the way back in the train should do the trick!

[Anonymous]

The gross tractive effort of a locomotive is driven by the friction between the wheels and track, and the weight of the locomotive. Better wheels are smoother, and give less traction. Too many locomotives are too light to pull much.

If you build it, and you can't quite make the grade, you can investigate adding weight to the locomotives. Lead is easier to use, but Tungsten is heavier and costs more.

Build it, test it, modify the equipment, do it again.

Good luck!

Mark in Utah
Proud owner of two AC4400's with 12 ounces of additional weight each. They'll pull anything.

[Anonymous]

Originally posted by David Foster

Has anyone done any recent research into what locos (and how many) will draw how many cars up what grades/ round what curves. We rarely use spirals here (UK) but I want to use three levels of staging tracks.

As this is a modelling query perhaps you should post to the Modellers forums instead of 'Prototype information for the modeler' forum.
You may be better read there.

OTOH, I've seen problems with just 2x SD's pulling/ trying 20 cars along moderate N scale grades
dave[xx(]

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