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Home > Rolling Stock > Rolling Stock Maintenance

Rolling Stock Maintenance

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coupler gaugeThere are a few basic tips and topics to keep your freight cars running smoothly. I have compiled this pages with information from many talented hobbyists, articles and my own experiences. This is not an exhaustive resource on freight car maintenance but this is what I do to keep my cars running reliably. 

Cars that do not stay on the track can lead to a very frustrating time.  Taking an interest in maintaining your cars will result in better operating.  Better operating cars leads to more fun running trains for everyone.

The Model - GTW Box Car

Grand Trunk Box Car

Freight Car Maintenance:

Tools Recommended
Maintenance Procedure
Coupler Basics
Coupler Maintenance
Car Weight

Car Assembly and Repair Tools Recommended

The basic tools are needed for general modeling, not just trains. The NMRA gauge is the exception but it is well worth the cost. You can generally find the tools at your local hobby shop or hardware store. I have provided a basic list to keep your initial costs down.

Xuron Cutters (SHEAR-2175)
Small Flat File
Small Screwdriver
Hobby knife with #11 Blades
1 Pair of Tweezers
1 Pair of Needle Nose Pliers
1 NMRA Mark IV Gauge (HO or your preferred scale)

Maintenance Procedure

Trucks - The wheels and trucks on your rolling stock should move freely from side to side.  Any stiff movement could cause your train to not follow the track properly. 

Wheels - Wheels should spin freely and in proper gauge.  Use the NMRA Mark IV to check the gauge of your wheels.  Make sure you check multiple points on each axle (two preferred) as wheels can be in gauge on one side but out of gauge when you check 180 degrees on the other side. You may want to improve your car by removing plastic wheels and replacing them with higher quality metal wheel sets.

Parts - Check to ensure that grab irons, ladders and other parts are secured to the model.  Take the time to fix the parts during regular maintenance to minimize lost parts and broken models.  Parts that fall of models can cause derailments.

Cleanliness - Make sure your wheels are clean.  Dirty wheels cause engines to run poorly on the track.  Metal wheels stay cleaner much longer than plastic wheels and they improve the performance of your rolling stock.

Coupler Basics

Freight cars and locomotives are held together by couplers. There is a standard coupler that is called a horn hook or X25 style coupler. When you buy a train set or low cost train cars they generally have the horn hook style coupler installed.

Horn hook couplers work fine when you run a train around in a circle. The down side of the horn hook coupler is that it does not look like a real coupler. The other down side is that once cars are coupled together it is difficult to get them apart without removing one car from the track.

The model industry has focused on more realistic couplers based on a universal coupler made by a company called Kadee®. Kadee® was the first company to offer a realistic looking coupler that operates reliably and easily uncouples without removing one train car from the track. As a rule I replace all my horn hook couplers with Kadee® couplers for the better looks and working characteristics. I feel this is a worthwhile expense and all my freight cars and engines have a Kadee® style coupler installed.

Kadee® couplers have been around for a long time and other manufacturers like Accumate® and McHenry™ make Kadee® compatible couplers. Some car kits now arrive with Kadee® compatible couplers so you don't have to replace the standard horn hook coupler with a Kadee® coupler before running the car in your train.

Coupler Installation and Maintenance

The following tools are needed when working with the Kadee® style couplers on your models. Good coupler maintenance will greatly enhance your experience when running trains. Trains that stay together make model railroading much more fun!


Kadee® Coupler Height Gauge
Kadee® #235 Spring Pic
Kadee® #237 Coupler Trip Pin Pliers
12" to 24" Piece of scale track
Swivel Head Pin Vise
#50 Drill Bit
2-56 Tap


Tube of Dry Powder Graphite
2-56 Screws 1/4" Long
2-56 Screws 1/8" Long
Kadee® #208 Red Insulating Washers 0.015 (Thick)
Kadee® #209 Gray Insulating Washers 0.010 (Thin)
Kadee® Coupler Height Gauge - This is used to make sure your couplers are the correct height from the ground. All the couplers on your train have to be the same height so they stay connected as the locomotive pulls them around the layout.

Kadee® Spring Pic - This item is used to insert springs on a Kadee® coupler. The spring holds the coupler knuckle closed to prevent the cars from disconnecting. This tool works in all scales for the Kadee® coupler line. If you have a steady hand you can use an X-Acto #11 blade to do the same thing. However, eventually you will want to buy one of these. It is very handy.

Coupler Trip Pin Pliers - This tool is used to bend the air hose on the Kadee® coupler. The hose may need to be adjusted to avoid snagging on switches and grade crossings on your model railroad.

Piece of Scale Track - Place the Kadee® Coupler Height Gauge on this piece of track to check your freight car coupler height. You can use a track on your train layout but be careful , the height gauge is all metal and will short out your power pack. If you are really good you can get two Kadee® Coupler Height Gauges and mount one at each end of your test track. This lets you check both couplers without having flip your car around on the test track.

Swivel Head Pin Vise - This is essentially a small hand held device used to hold a drill bit. Using a pin vise you can drill very small holes in your models with exact control. The pin vise is used in with the drill bits and taps listed below.

# 50 Drill Bit and 2-56 Tap - These items are used in the pin vise to drill and tap a hole. This will allow you to mount a coupler box directly to the body of a freight car.

Screw Size
Tap Drill
Clearance Drill
 0-80 55
 1-72 53 48
 2-56 50 43

2-56 Screws 1/4" and 1/8" Long - These are used to attach our couplers to the freight cars. After some use the coupler boxes on Athearn® brand cars may loosen and fall apart. A 2-56 screw can be used to secure the coupler box and add strength to the freight car.

Kadee® Insulating Washers - Washers are used to raise the height of your freight car so your couplers match the correct height on the Kadee® Coupler Height Gauge.

Coupler Maintenance Procedure

I am assuming that you will use a Kadee® #5 universal style coupler on your freight car. The basic strategy when installing couplers is to ensure that all contact surfaces are smooth. This will allow a coupler to travel freely from side to side inside the coupler pocket. If you use a different coupler the basic strategy is the same, reduce friction to increase reliability.

  • Burnish the shank of the coupler with the smooth end of a drill bit. The shank may be irregular due to the casting process used to manufacturer the coupler.
  • Lightly file the edge of the coupler centering spring with a small file. This removes any lip that may be on the edge of the metal spring as a result of the stamping process.
  • Lightly file the top and bottom edges of the coupler pocket and pocket cover. This removes any burnishes on the plastic pocket edge.
  • Insert spring and coupler into coupler pocket.
  • Attach pocket cover to model with 2-56 screw or snap on (Athearn) pocket cover.
  • Check with your finger that the coupler can swing freely from side to side on the car. If not you can loosen the coupler screw to reduce friction and add powdered graphite into the pocket until the coupler swings freely.

  • Check coupler height against the coupler height gauge on your test track. If the coupler is too low, use the washers to raise the car to the proper height. If the car is too high use an offset shank coupler to lower the coupler to the proper height.
low coupler
 perfect coupler
  • After the coupler height is set correctly make sure the trip pin (air hose) does not sag below the rail. This can be checked on the coupler height gauge. If the trip pin is too low you can adjust it with the trip pin pliers.
Car Weight

Cars manufactured today vary in weight and this can have an impact on how well your trains run. The NMRA has done the research to determine the best weight for your model freight cars. I have added weight to my models and noticed a marked improvement in performance.

The following tools and supplies will be needed to properly weigh your cars.

Postal Scale - You can purchase a cheap postal scale for US mail at an office supply store. When you get the scale make sure you balance it with a 1 oz weight to verify the scale is accurate. You can use better digital scales for more accuracy if you like, I have found the postal scale to work fine on my fleet of rolling stock.

Self / Stick Lead Weights - A-Line™ offers a set of self stick lead weights to add to your freight cars. The weights are available in 1/4 oz and 1/2 oz denominations. You can use lead as a weight as long as you secure the weight in the freight car with some sort of adhesive such as Walthers Goo™.

Walthers Goo™ - This is an adhesive that is useful for securing weights in freight cars. When the glue dries it is still a bit flexible and it can glue different surfaces together such as metal to plastic or wood. This glue can be used in conjunction to the self sticking weights in situations where the weights do not remain secure.

 Car Weighing Procedure

Take freight car out of the box and with a ruler measure the length of your model. Use the following guideline to determine the desired weight of your model.

 Additional Weight
for each Inch of Body Length
 HO 1 oz

 1/2 oz

We basically want to start off with one ounce of weight for HO scale. After measuring the freight car we add 1/2 oz for every inch in length. A HO scale freight car that is 4 inches long will need a total of three ounces. This is based on the NMRA Recommended practice 20.1

Before you assemble your freight car place all the parts (not the box) on the scale and take a reading. If the reading is lower than our recommended weight we calculated above put a few weights on the scale. Keep adding weight until you reach the recommended weight for the kit.

model sitting on a scale

During kit assembly you may want to add the weight inside the car so it is hidden. You may have to be creative when assembling a flat car. In that case you could add a flat car load to increase the weight of your model.

© All manufacturers retain full copyright and trademark rights to referenced products on this page. Athearn, Kadee, Accumate, McHenry, A-Line, Walthers Goo, are trademarks to their respective companies all rights reserved.


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