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Derailing On HO Track
John has several question for experienced model railroaders to answer:
“I have just built my first HO layout in the shape of a 1/2 dogbone with the two outside ends being 40″ wide. This limited me to a radius of approximately 18”. I have two Seaboard passenger locos with 6 wheels on each set of trucks and am experiencing problems with the locos de-railing going around only some of the curves. Am I doomed with these locos? What can I do to make them work? Does this sound like I may have an issue with my track at these locations? How can I make my track curves be more perfect?”
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4 Responses to Derailing On HO Track
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Hi John, sounds like your radius is too tight for your locos. this is especially true on the longer ones such as the steam, big boy, and the, challenger, they can NOT make the sharpe turns. Usually your loco comes with instructions on the MINIMUM radius usable for that loco. If you used flex track and you have a slight kink in it you have a problem, replace it, or too much of a bend (Radius), if you used smaller sections of track and you did NOT maintain the TRUE curve and there is a separation at the joiners or a kink you have a problem. so you need to check all of these to see where the problem is, the flow of the track needs to be smooth. so you may just have to run your longer locos on the larger radius out side tracks only. dont feel bad we have all done this and sometimes still do to get that extra turn in some where and then need to correct it or live with it with smaller loco’s and rolling stock (Cars). By the way once you get it to where you are happy with the operation of your trains solder all of your joints very carefully. If you are not familiar with this get Roberts book or help from a more experienced model RRer. Tony P
John,
Yes, you may be doomed. 18″ radius is pretty tight in HO although most equipment SHOULD be able to operate on it. If the derailments always occur in the same place, you may have a slight kink in the track which is made worse by the fact you’re running 18″ radius curves. Run your finger along the inside of the rail and see if you can feel any rough or uneven spots. If you do, either relay the track OR carefully file at the rough area taking care not to remove too much rail material.
If you end up starting over and relaying the track (which is actually the best way to go), some folks like to ease into curves using a broader radius (like 22″) followed by the 18″ radius track. This way your trains won’t suddenly go from a straight section into a sharp curve (train speed plays a part in this as well) and the space needed for the track isn’t that much different.
Avoid S turns in you track plan unless you put a short straight section between each side of the ‘S’. This straight section acts as a transition or easement piece.
If you are using flex-track instead of prefab sectional track, you can purchase track laying jigs that go in between the rails as you secure the track to the road bed or table top to help you create smoother curves. They come in various radii and straight sections and are relatively inexpensive. Any good HO hobby shop should have them or be able to get them for you.
As far as your locos are concerned, the six wheeled trucks may not have enough play in them to negotiate the curves though this is unlikely. It may be that the trucks are hitting the undercarriage of the engine when in the curves causing them to bind. If this is true, you might get away with filing away some of the upper truck surface(s) or the underside of the loco’s body, which ever is easier. Obviously, this is a last resort and care should be taken not to damage the overall appearance of the models.
If it is the same loco that does the derailing then the problem is obviously equipment and not track related. If this is so, then close examination of the engine as it slowly runs over the trouble area(s) may provide a visual clue as to what is going on. If you see that the wheels are riding up and over the rail head then you may have a rail kink or the axle spacing between the wheels may be a tad off.
If this is so, you may want to purchase an NMRA standards gauge for HO scale which allows you to check wheel & track width, coupler height and building clearance among other things. Sometimes your equipment can get ‘out of whack’ just from simple handling, wear and tear or a even screw up at the factory. The gauge will help determine if everything is in its proper place or setting.
Hope this helps,
Geof
Make sure all your joints are smooth, it’s easy to mis-align a joiner and have a high spot in one of the joints.
Alternately, you might have a spot where the gauge narrows a bit or you might have two curved pieces that aren’t exactly aligned which will cause the radius to decrease at that spot.
If you are constantly derailing at the same spot, check the trackwork.
Otherwise, your 6 axle diesels may just not be happy on the tight curves. You might have to downsize. I have a similar problem with steam engines on my N scale layout, I used the train-set 9 3/4″ curves and my more expensive locos don’t like it at all. Next time around my minimum radius will be 15″.
John; I would first see if the engine truck is binding up against the body of the engine, if this is not the case then the next step is to get a track radius gauge,and reline the track. If your using flex track you may have sharper kinks in it reducing the radius further, this should straighten this problem out. If you completely out of room and nowhere to grow try a more exotic approach wide gauge your track in the curves and avoid NO4 turnouts! Alan C Lompoc, Ca.