weight

Cars which are too light do not track well.  They wobble and won't couple properly and tip over on curves if they are in long trains and the curves are sharp or on a grade.  In order for performance to be predictable with a variety of equipment mixed somewhat randomly in trains, it works best if the weight is consistant and distributed throughout the train at about the same amount no matter what order the cars are in.  Having cars match NMRA weights provides the consistancy and predicability you need for reliable performance.

Some cars are a challenge to get up to proper weight.  Boxcars and such with lots of interior space can be weighted with anything handy, so long as you use a reliable adhesive to mount the weight (CA and such sometimes gets brittle and the load will come loose; a flexible adhesive like double sided foam tape is often better.)  Flat cars and skeleton flats are often the hardest to weight.  Lead is the cheapest heavy material, though there is a lot of concern about lead poisoning when handling it.  Tungsten is even heavier, but quite a bit more expensive.  Using the heaviest material is useful when you have limited space.  

Some cars, like the Atlas trash flats, have no room for weight which could not be seen when they are empty.  The solution is to weight the loads, though that may not work if you want to run the cars empty.  Railroads often have special instructions limiting empty cars like these to the back of trains for the same reason; they don't track well with a lot of weight behind them in the train.

weight

Ditto on everything Jurgen says. Most RTR stuff you buy now is already properly weighted. Exceptions being open gondolas, hoppers and flatcars. Older enclosed cars can be weighted by gluing weight inside. I use pennies and Walthers Goo. Others use nuts and bolts or old lead tire weights. On open cars, many modelers substitute pieces of sheet lead for the steel weights. I just add a load of some type. I have a few empties for variety and I run them near the back of the train as Jurgen wrote.

willie

weight

Postal Scales

You need to measure accurate ounces and half ounces.  Get a cheap postal scale or kitchen scale, they will provide a reason level needed.

Scales

There are many scales capable of measuring in the weight range for N and HO cars. You will need a scale that measures accurately to 0.1 oz or better. Low cost spring postal scales for very small packages and letters and similar small kitchen scales can be used; however, spring scales have only moderate accuracy and repeatability. The good old laboratory balance scales have great accuracy and repeatability, but these days, unless you find one at a garage sale, are relatively expensive. Electronic scales offer great accuracy and repeatability, and the prices have come down to the $30 -$60 range. Just do an online search for Small Scale and you should find what you need.

For example this is the scale I purchased several years ago for $29: http://www.staples.com/Pelouze-5-lb-General-Purpose-Digital-Scales/product_499322.The US-Brovo Pocket Scale also looks promising at $21.99: http://www.scalesonline.com/p/3680/us-balance-us-bravo-pocket-scale.

I check my scales with standard weights several times a year to verify accuracy.

Weighing Rolling Stock

I use a variety of flat washers, 3/8", 5/16", 1/4", 1/8" and if I have a particularly special car that I want weighted spot on, I dig into my stash of 10-32 and 8-32 washers.

Little electronic scale

This is the one I use from Harbor Freight

I use lead shot that my Dad had for reloading shotgun shells, though lead shot may be hard to come by these days.  Steel shot would work just as well, but it would take more of it to reach the same weight.  Another place to look is your local stained glass supply.  The lead channel used in that craft can be cut up for weights, or cut down to make structural shapes.  Wear gloves and wash your hands after working with lead - no eating or drinking while doing it! (smoking either)

International measuring system

I understand NMRA is an American association and uses imperial units, but I am a Brazilian (alhough I model an american prototype) and here all scales read grams. Is there any table using international measuring units?

grams per ounce

2.2046 pounds per kilogram or 28.35g per oz

Search the web for "kilogram" will come up with conversion formulas, definitions and tables.

Terry

Bem-vindo

You could check for the equivalent norm (NEM) [I think NEM 302] on the European Union of Model Railroads (MOROP) (http://www.morop.eu/en/idf/index.html) or the Associação Portuguesa dos Amigos do Caminho de ferro (APAC) (http://apac.cp.pt/) sites. Otherwise I would just use a spreadsheet program to provide an equivalent table where one ounce is equal to 28.34952 grams. You could also use one of the online converters such as: http://www.metric-conversions.org/weight/ounces-to-grams.htm.

You should probably check my math.

weight

thanks

Thank you very much Ken and Terry. This info will be really useful!

Daniel

Metric

I suppose the chart should suggest number of grams per additional 25mm of car length. People dealing with four-wheel freight cars, instead of the common North and South American eight-wheeled cars might want to take a different approach to weight. 

One past club used a graph with weight on the vertical access and length on the horizontal access. Once a couple data points were arithmetic'd into the chart, it was fairly easy to draw a line and find the needed weight for any given length.

Metal wheels

If your cars are light and have plastic wheels, consider replacing the wheels with metal ones. The metal wheels weigh more and the weight is about as low as you can get (a lower center of gravity is better). As a bonus, metal wheels tend to roll better, track better, and pick up less dirt/dust/crud than plastic wheels.

If the car is still light after adding metal wheels then add weights. They cost slightly more, but lead weights are available (from A-Line iirc) with self sticking foam tape on them in 1oz and 1/2oz sizes. Snip the weights off the strip and stick 'em on. Easy peasy.

Charlie

You can also get those stick

You can also get those stick on weights from places like Harbor Freight and not have to pay to ship them

Tire Shops

I get mine from a tire shop and they won't even let me pay for them.

Roy

Archaic at best.

  I believe the NMRA recommendation is archaic. It was born out in a period where track work was lousy and fiber ties that swelled and shrunk and snap switches were common. Not many hand laid and sectional brass track was the norm. The NMRA figured that stuffing a car with weight would make it stay on the track better and it did. It also gave an excuse to accept bad track work as normal.

  There are many things that we can do to improve rolling and tracking of our freight and passenger cars. Free rolling metal wheels that are in gage and parallel to the truck frames is a biggy. Couplers that swing freely and at the right height and has the trip pin adjusted properly. Trucks that swivel freely and adjusted to a slight 3 point suspension. And track work that is smooth and free flowing.

  I did an experiment at our club one night. I took  an Athearn 40 foot flat and removed the steel weight, added free rolling metal wheels and checked out the car for rolling and tracking. I put this car behind the tender of a 2-10-0 and added 39 hoppers with loads and a cabin. This train took the layout without a derailment or an un coupling. Even the long 2.5 percent grade and helix did not make any difference. Gasps and the unending I can't believe it was all I heard. There are guys in the club who pay little attention to the rolling stock but they add weight to try to keep it on the rails and still have problems. Many love those RTR cars and just plunk them down and expect them to run. After 4 or 5 retrievals they remove them and tell you how much they paid for junk. They always ask why I don't have problems and why my cars are so light? They also ask why my engine can pull 10 to 20 more cars then their engine of the same make and model. I still have the weightless flat car and frequently run it. I have found that the weight that comes with the car kit is more than sufficient.

        Pete

archaic or not

I have found that the overall long term performance, read tracking or derailments, is improved when the cars weigh according to the NMRA standards or a set of standards that have weight specifications according to length.

I happen to use NMRA standards, including weight, gauge and others, to train lengths in excess of 100 cars that have worked fine.

BTW-Master Brugger, you were up way too early today.

Terry

archaic?

Try your experiment again with an 89 foot flatcar or better yet, a tri-level autorack, and then let us know how many pieces it was in when you gathered them from the floor under the helix.  A forty foot flatcar is about the most stable piece of rolling stock you can put on your layout.  The problems increase geometrically when you make cars taller and longer, and move the bolsters farther in from the ends of the car.  And I imagine that you either couple at 30 scale mph or enjoy chasing your cars the length of the yard while trying to make a joint.  It can be hard enough to try to couple to a car weighing 7 ounces without it wanting to move, at 2 ounces it would be virtually impossible.

Bring it on. I'm ready.

Jurgen

   I knew I was going to get a lot of flack for this. I think like the prototype and that weight is a detriment and the less weight I have to pull or push the better. The only things I add weight to is my locomotives. If the car comes with the sheet metal weights than I will use them.  Does your locomotives weight scale up to what the NMRA would recommend? None of us have three or four pound HO scale locomotives. Remember it is not a standard but a recommendation. What I am saying is  we should be paying better attention to our couplers, wheels, track work and trucks and less attention of stuffing weight into a car that does not really need it. Do as you like but do not tell someone to do something that is not really necessary for smooth operation and an excuse to ignore bad track work or out of square truck frames.

   Not my era or prototype but, there are club members who run those empty spine cars with no loads all the time. Either in mixed freights and container trains. You can't get much lighter than those. As for coupling. Our yards employ the old paint brush bristle weed growth along the center and edges. The scale tracks have magnets for the couplers at both ends that keep the cars from rolling and makes weighing a hands off and no skewer needed for uncoupling. My couplers all work properly so I don't need to slam into a car to couple it. On many I have removed the centering springs and shimmed them so they don't sag but swivel freely. With the capture range of the KD there really is no issue except after the magnets move them and I can even couple on curves.

  See question 9 and 10. Steve Hatch agrees with me.   http://www.railwayeng.com/rrhints.htm

          Do as you want.That is the beauty of this hobby.

            Pete

ditto on Postal Scale

A Railroad is basically a big, spread out, Machine.

Therefore it works according to the practical version of the laws of Physics, aka Engineering.

As far as the track and wheels are concerned, a model railroad is the same machine in miniature, and must obey the same laws, but with the disproportionate scaling down of values of the variables, like weight (cubic ratio) and size (linear ratio), but not time or gravity.

Since model cars are disproportionately lighter than the real things, but time isn't faster, hitting a track bump is going to displace a wheel or a car body a whole lot quicker and much further up. Add the fact that model bumps are proportionally a heck of a lot larger than those on the prototype and we have a major maths exercise to work out what actually helps TRUE TO SCALE model cars stay on the track. (Which would have working scale suspension of course).

Using proportionally deeper NMRA standard wheel flanges however IS a deliberate and valid engineering solution for bumpy model track, and it works 100% as is – without anyone narrowing the gauge at the frog on their turnouts, for example. But it can’t completely compensate for doing really wild things that real railroads can’t do either, like running 100 car trains up 3 turn helixes of 180 ft radius

Sure you can do whatever you want on your own model. And you can add all the art and beauty you can muster, but those two factors will only affect the scenery.
 

AMRA variation of weight standards - metric

Here in Australia we have a variation of the weight standards expressed as weight (grams) per millimetre (g/mm). There are a variety of scales listed but for those modeling HO (1:87.1) it is 0.55g/mm +/- 15%. I would call this 0.6g/mm myself!

The standards are published here: http://www.amra.asn.au/massstandard.pdf

Most commonly available digital kitchen scales will provide a 0.1g reading increment.

Something rather different to the NMRA standards is that the Australian standard also lists a separate weight standard for passenger rollingstock (0.4g/mm:HO scale) The rationale is that prototype passenger rollingstock weighs less than a freight wagon of the same length.

Also different to the NMRA is that the Australian standard is lighter than the NMRA standard. This is for similar reasons expressed earlier related to freewheeling wheel sets and properly operating couplers.

Another interesting comparison (for me at least! )  ) is that the topic of "standards" elicits very strong opinions in almost every direction here in Australia as well!

Happy model trains to all!

Dan

Adding weight down low

I haven't done much running--yet--and won't until I move.  But replacing stock trucks with Kadee metal ones definitely helped me on some bad trackwork now and then.  (For now, the only place I've had to run recently is the dining room table with Atlas True-Track with the built in roadbead.)

The Kadees added weight nicely, and I could run without derailments--even though the trackwork was terrible.  Of course, I was running short trains--the most was a 6 or 7 car mixed freight.