About car weight

[Russ Bellinis]

I don't want to go off topic, but I usually run 1930s-'60s, short, 4-wheel, freight cars on my British 00 layout. I find that these cars are more sensitive (especially if they're really light) & prone to derail than their North American equivalents. Trouble-shooting these cars can be quite different from fixing the 2-truck/8-wheel kind. Rob

I think the main reason that your 4 wheel cars are more sensitive is because of the wheel base. On American prototype you have two short wheelbase 4 wheel trucks at each end on a pivot. On the British prototype, you have an axle at each end of the car, and I don't think either of the axles will pivot. That means that the wheel base of that one truck on the British car is much longer than either of the two on the American prototype.

[RobertInOntario]

I don't want to go off topic, but I usually run 1930s-'60s, short, 4-wheel, freight cars on my British 00 layout. I find that these cars are more sensitive (especially if they're really light) & prone to derail than their North American equivalents. Trouble-shooting these cars can be quite different from fixing the 2-truck/8-wheel kind. Rob

I think the main reason that your 4 wheel cars are more sensitive is because of the wheel base. On American prototype you have two short wheelbase 4 wheel trucks at each end on a pivot. On the British prototype, you have an axle at each end of the car, and I don't think either of the axles will pivot. That means that the wheel base of that one truck on the British car is much longer than either of the two on the American prototype.

Hi Russ,

Yes, I think you're right. Also, when you factor in that many of these British freight car models are fairly light to begin with, and you can see how they will easily derail. This often happens when I'm reversing a long freight train through some turnouts or tight curves. Overall, these British freight cars work well but they're nowhere near as stable or reliable as coaching stock.

Rob

[pgandw]

Weight in your cars won't improve track work.

Weight will improve our model car's suspension and track springing - if they have any. That's because it's relatively difficult to get model truck springs to work properly under a wide range of weights. So truck springs tend to be on the stiff side - Kadee sprung trucks being an exception in HO. So part of the NMRA RP weight was to encourage proper spring reactions of our model trucks. When our locomotives and cars have proper springing, the wheels equalize and can track over rougher track than with rigid frames. Which is one of the reasons why the prototype uses springs and equalization.

OTOH, modern production uses rigid frame trucks on cars almost exclusively. They are cheaper to make, and can have finer detail than sprung trucks. Track work is generally to a higher standard than it used to be decades ago, so springing and equalization aren't as necessary. With steel needle point axles turning in plastic or metal rigid frames on car trucks, adding weight increases the wear on the needle point bearing surface in the journals. Observe a Athearn car truck after many hours of running - especially if weight has been added to the car. You will see the the needle point has worn the journal, and the wheel set rides higher in the truck than it once did (you can detect this by observing that your couplers are low for no reason, when they were once on spec). Finally, modern plastic locomotives don't weigh as much as their die cast predecessors do. They can't pull as much. If space has been given over to the speaker and electronics, the locomotive weight is reduced further. So the advice not add weight to modern production cars makes sense, too.

So it really depends on your situation whether adding weight is a good idea. If you are using sprung metal trucks on a switching layout, and maximum length trains are not in the cards, weighting your cars to or beyond the NMRA RP is a good thing. OTOH, if you are running rigid plastic frame trucks on your cars and want to pull long trains with modern plastic engines, I would keep the weight to 3/4 or less than the NMRA RP. Just remember that the track work has to be a little bit better to prevent derailments.

my thoughts, your choices
Fred W

[Puddlejumper]

With steel needle point axles turning in plastic or metal rigid frames on car trucks, adding weight increases the wear on the needle point bearing surface in the journals. Observe a Athearn car truck after many hours of running - especially if weight has been added to the car. You will see the the needle point has worn the journal, and the wheel set rides higher in the truck than it once did (you can detect this by observing that your couplers are low for no reason, when they were once on spec).

Particularly a problem when running "live" loads in open cars such as coal, like I plan to do. My train lengths will be limited to 15 or so cars, but with live loads will require 3 units to pull... and periodic replacement of the trucks.

[jim currie]

no matter what you weight your stock to the important thing is to have them all close to the same weight(I still run some old MDC cars so i weight the rest of my cars to match them ) if you run light cars close to the loco's and heavy ones after them then you will have trouble on the curves (called clothes lining) the heavier cars pulling the lighter cars off to the inside of the curve.no matter how good or bad your track is.
jim