North Raleigh Model Railroad Club

Freight Car Standards

This publication was authorized by the Standards Committee on April 19, 1995, and proposed to the general membership. It was ratified by the Club on August 2, 1995

Although the prime emphasis of modelers is usually on locomotive performance, most show problems occur with freight car derailments or break-aways, either truck and/or coupler problems, track problems, or a combination of both. So-called ready-to-run freight cars in N-Scale still need some adjustments to give reliable operation. As our average train length continues to increase, the need to test and adjust each freight car becomes more important. This publication addresses the following topics:

trucks and couplers
weight
general appearance

Painting, weathering and decaling will not be covered in this publication, although cosmetic flaws (not to be confused with legitimate weathering effects) are cause for prohibition from Club layouts at Shows.

Any corrections or suggestions for changes or improvements to this publication should be directed to the Chairman, Standards Committee, North Raleigh Model Railroad Club.

Although the number of rolling stock kits in N-Scale is increasing rapidly, most of our equipment is pre-assembled in convenient plastic storage boxes. Of the major manufacturers, only Model Die Casting (Roundhouse) cars normally require some assembly, mostly with the underframe and trucks. Manufacturers such as Intermountain are now offering very nice and somewhat difficult car kits; the assembly of such kits are beyond the scope of this standard, but everything else included here applies.

Before any new item of rolling stock is first used on the layout, as a minimum, the trucks/couplers should be removed and the underbody separated from the car body. For some cars this may be as simple as an Atlas 90-ton hopper or somewhat complicated as a MicroTrains covered hopper.

First check the gauge of the wheel sets; this is important as any defect in manufacturing will show up at this time. This is also a good time to look for flash and stubs where the plastic item was separated from the sprue. Replace any wheel sets which do not spin freely. This can be easily checked by spinning the wheels in the truck or letting the truck roll down a slight grade. To set a standard, a freight car truck should be able to roll freely down a 30" length of track with a 1/4" grade.

Consider at this time replacing the wheelsets with low profile wheelsets available from MicroTrains and Precision Masters. (Note that some newer trucks from Atlas and Model Die Casting [Roundhouse] are factory equipped with low profile wheels.) These low profile wheelsets meet the NMRA RP-25 Recommended Practice.

Some modelers automatically replace all trucks (or, as a minimum, any trucks with any problems) with MicroTrains trucks and wheelsets.

Next, check the coupler operation. For Micro-Trains couplers, use the Catalog Number 1055 Coupler Height Gauge to ensure proper alignment. Inspect the knuckle for any flash or casting defects. It is always a good idea to take a small needle file to clean up the knuckle so that the coupler does not ride up or down when under a load. A little MicroTrains (Catalog Number 231) Greas’em Dry Lubricant (powdered graphite) in the pocket is a good idea, even for Rapido style couplers. Most problems with the MicroTrains coupler is with the trip pin, which should be carefully adjusted so as not to be too low where it will hit or hang on the track in turnouts (or road crossings); use the MicroTrains (Catalog Number 1056) Trip Pin Height Gauge.

Inspect the trip pin with the trucks mounted to the car pulling slightly, with the Coupler Gauge, to put some pressure on the knuckles. This action should show if the coupler tends to ride up or down. If you suspect a problems then it will probably require that the entire coupler be disassembled and rebuilt.

For Rapido style couplers, there is no height gauge available, so make one by taking an atlas truck and hot gluing or ACC gluing it down to a section of flex track. Inspect the truck coupler for any flash or casting defects. Use a small file to clean up the flat surfaces on the coupler. With the truck attached to the car body, check to see that the coupler rides up (or down) over the gage coupler and drops into a good joint. A slight tug on the coupler will indicate a good connection. If the two couplers tend to ride up and appear to want to separate, then there is a problem which may require complete disassembly and coupler replacement.

Before attaching the truck to the underframe, lightly file the bolster face. This important for all freight cars, even Micro-Trains have problems here. A good way to accurately do this is to glue a piece of #400 grit wet/dry sandpaper to a very flat surface such as an 8" long by 2" wide pine board. Take the car underframe and gently run it back and forth across the sandpaper a few times. Too much sanding is not necessary and may damage the frame beyond repair.

Model Die Casting (Roundhouse) metal underframes require some filing and general clean up, plus painting. The flat section of the frame between the end of the car and the bolster must be filed flat to eliminate the casting marks. This will allow the coupler pocket to swing free under the car. The frame should be painted flat black. After the paint dries, it is again necessary to clean the paint off the bolster face by light sanding.

Apply a little Greas’em Dry Lubricant to the bolster face before attaching the truck to the frame. Use a Phillips screwdriver or the Aztec pin pusher tool to firmly push the pin into the bolster so that the pin shoulder is tight to the frame. When using a MicroTrains truck on a Roundhouse car, it will be necessary to use the spacing washer to keep the wheel sets from rubbing against the frame. The washers must be sanded flat before use and a small amount of Greas’em applied.

With the car assembled, make sure the trucks sit flat on the track; all wheels should rest on the rails. The entire car should be square to the track and not lean to one side. A bent frame or twisted bolster must be corrected if the trucks are not level on the track.

The final check is to take the assembled car to the test grade; the car should freely roll without any resistance. If the car shows any hesitation to freely roll then you can expect problems on the layout. Fix any remaining problems now.

The NMRA Recommended Practice 20.1 "Car Weight" provides guidelines for consistent car weight that contributes to a better running model railroad. Most Atlas, Model Power, and Roco cars are less than the recommended amount; most MicroTrains and Roundhouse cars are about right.

For N scale the recommended weight is an initial weight of 0.5 ounce (14.2 grams) + 0.15 ounces (4.3 grams) per inch of car length. For example, a 40’ box car is 3" long so it should weigh 0.5oz + (3 x 0.15)oz = 0.95oz. Because these end up as odd weights, it is frequently more convenient to work in grams. The following table provides recommended weights for various car lengths:

A postal scale can be used as a weighing device especially if it weighs in the 1/4 ounce range, or in grams. As well, a simple-to-make balance scale can be used. For balance weights you can use lead sinkers (which come in 1/8, 1/4 and 1/2 ounce sizes), or coins (dime – 2 grams, cent – 3 grams, nickel – 5 grams, quarter – 6 grams). Car weights need only approximate the recommended value.

The best way to add weight is by using fishing weights and hot glue or ACC. The location to place the weight varies widely from car to car but it is a good idea to work with several small weights rather than one large weight. It is very important to keep the car balanced and always add the weight as close to the bottom of the car as possible.

A small postal scale for weighing letters is adequate to determine which freight cars may need additional weight.

Although this does not affect the technical performance of freight cars, it is still important to maintain the appearance. Only a few general guidelines here:

1. No broken or missing parts - This includes such items as missing brake wheels, broken ladder stirrups, broken roof walks, etc.

2. Remove Dirt and Dust - Some may consider this 'natural' weathering, but there is a limit. Cars which have sat idle for an extended period of time will collect dust. A soft tooth brush and some soapy water will do wonders to bring back the original appearance.

3. Avoid poor painting and decaling - a poor paint job will stand out and be noticed quicker than any defect. If an experiment doesn't turn out; set that car aside to be stripped and done over. Seek advice from the experts.

4. Be careful not to use excessive glue - There is nothing more disappointing than a 40 ft flat car load that has huge globs of hot glue visible. When gluing ensure that parts fit and are to scale, and parts sit flush and don’t overhang, etc.

5. Eliminate Shimmy - freight cars that appear to vibrate as they roll along in a string of freight cars.

A little bit of time getting things right when a freight car is purchased or built, or when maintenance is performed on a freight car, will pay off in a smoother running railroad.