The weight of HO rolling stock??

Model Railroader Prototype information for the modeler
1

I’d like to add weight to my rolling stock. I’ve heard that there is a standard that I should follow, as to how much each car should weigh. If someone could help me with this, I’d thank you very much!!!

Thanks again!!!

Robert

2

Robert, I think that it’s an NMRA “recommended practice” rather than an actual standard. In HO, it calls for car weights of one ounce plus one half ounce for every actual inch of length. So a 40’ boxcar, at approximately 6" length would weigh 1 oz. plus six half ounces, or 4 oz. total. Similarly, a 50’ car would weigh 1 oz. plus seven half ounces, or 4.5 oz.

I’ve found that as long as your wheels and track are within specs, reliable operation is possible with rolling stock at almost any weight, provided that it’s all within a reasonable range. Cars that are markedly heavier or lighter than the majority of the cars in a train are usually the ones that cause trouble. These problems can be minimised by placing the heavier cars up front in the train, with the lighter ones at the rear.

However, if you’re running a train of all over-weight or underweight cars, problems should be few. I generally follow the NMRA weight guidelines, but run a coal train that uses “live” loads. Athearn two-bay hoppers thus loaded weigh 8 oz. while the empties tip the scales at only 1.75 oz., but trains made up of all of either type track well.

By the way, [#welcome] to the Forums.

Wayne

3

http://www.nmra.org/standards/sandrp/rp-20_1.html

Jim

4

I don’t really use a weight standard for my cars. For the most part, I use the weight that comes with the cars or kits. Once in a while I find that the factory weight is not quite enough. I can usually tell by how the car feels in my hand. In that case I will add some weight. I also have an electronic postal scale to check the car weight so I don’t add too much weight to it.

What I find that matters more than the weight is the wheels and couplers. I use an NMRA gauge and check the wheel gauge on EVERY CAR. This is done when I am getting the car ready to go on the layout. I also check the height of the couplers using a Kay-dee coupler height gauge. I also make sure the coupler pins (simulated air hoses) are slightly higher than the gauge calls for.

5

Thank you…all! I’ll go from the info. you have given me!!!

Happy holiday’s all!!

Robert

6

I’ve found that recommended or ideal car weight, like so many things in model railroading, vary with what you are trying to achieve, as well as your personal preferences. My experiences are this relative to the NMRA RP:

  • If you want to run long trains of many cars, the NMRA RP is too heavy - especially in light of the reduced tractive effort of today’s plastic locomotives. 3/4 (or even less) of the NMRA RP is sufficient for running long trains on broad curves - but trackwork does have to be pretty much “very good” to “excellent” to avoid derailments. Long trains on sharp curves don’t work very well with light cars.

  • If you prefer today’s plastic, rigid side frame trucks with metal axles, keeping car weight lighter than NMRA RP will reduce wear on the side frames where the needle points bear.

  • If you are heavily into switching operations, NMRA RP weight or heavier (I know folks that weight their cars to 1.5 times NMRA RP on switching layouts) leads to better coupling and uncoupling. Automatic coupling of very light cars on very free rolling trucks is not always reliable - don’t ask me how I know this. Similarly, uncoupling heavier cars with either magnets or manual picks is easier than their lightweight brethren. The heavier cars don’t derail as easily with the pick action. And they are easier to induce slack or keep slack out.

  • If you prefer metal sideframe, sprung trucks (Kadee, Central Valley, Cliff Line, etc), heavier car weights will allow the springs to work better. The trucks will equalize the way they are supposed to, which allows the wheels to better follow any vertical deflections in the track.

7

I fabricated a board to help out with this. It has a Kadee gauge mounted on one end, and RP weight marked along its length.

!(http://i184.photobucket.com/albums/x218/MFJ_album/Model trains/8-22-09003.jpg)

The board is maybe 18" long, plenty big for most cars.

!(http://i184.photobucket.com/albums/x218/MFJ_album/Model trains/8-22-09004.jpg)

I usually go for the RP weight, or a little heavier. Cars seem to stay on the track better, and not stringline as much. A the club we have a wicked turn at the top of a hill, with some cross-level issues thrown in for good measure.

!(http://i184.photobucket.com/albums/x218/MFJ_album/Model trains/Club stuff/7-19-09010.jpg)

The autoracks are a bit heavier than the RP, and now have body-mount couplers, the Walthers swing arms have been removed.

Properly mounted and functioning Kadee couplers and free-rolling trucks are also important.