Quote from: Doneldon on June 20, 2011, 10:47:01 PM--D, yes I have horn hook couplers on my freight cars; most are hooked to the trucks; any suggestions on changing them to kd couplers? Thanks for all the info. as a new railroader, I need all the help I can get. I wanted a hobby that my 9 year old daughter and I could do together. We both love the trains! bk
bk-
You are inquiring about one of the most common problems with HO trains. The reason is that backing a train manages to bring all of the common tracking problems together at one time. These include faulty track work, coupler problems, truck problems, incorrectly weighted cars, and injudicious speed. I assume from your post that you haven't noted a pattern to your problems, e.g., a particular car which derails or a specific turnout (switch). Let's look at each of the possible culprits in turn. But remember, backing through turnouts can allow marginal problems to work together to create an issue though they might not be a problem by themselves under less challenging circumstances. So check each possible problem even if you find a given problem before checking all of them.
Faulty track work: There are several things to check, including the gauge of all parts of the turnout and the track the train will move on to after the turnout. You need to look carefully at gauge and make sure that all rails are in gauge. An NMRA standards plate will be very useful for this. Sometimes the gauge is wide which allows the wheels to fall off of the rails. Or, they can be too close so they squeeze the wheels up and off of the rails. So check the gauge at several points, including at the rail joiners which connect to the adjacent rails. Make sure that they are correctly on both pieces of rail so there isn't a bump at the transition point. Next, check any guard rails in your turnout. These are the short, bent rails which serve to guide the wheel flanges. Depending on what kind of turnout you have, these might be separate pieces of rail which are incorrectly placed or are loose and getting in the way. Then look at the turnout's points. These are the two pices of rail which move back and forth. They should move from contact with one rail to contact with the other. The top of the rails which move should taper to a fairly sharp point and nestle into the rail they are moved to. And they should stay where they are put. The frog is the wedge shaped piece of rail where the two tracks diverge. This should be lined up perfectly with the rails which lead into it. Last, and your problem is likely to be either here or with the points, make certain that your turnout is level. Non-level turnouts can cause binding or misalignment which can be deadly, especially when backing up.
Couplers: I don't know what kind of couplers you use. Many set trains come with the so-called NMRA, X2f or horn-hook couplers. These are all names for the same cruddy coupler which really doesn't look much like a coupler. If you have couplers which don't look like the real thing, you probably have these. They look from the top like an egret with a very long top knot on the back of its head. Lose them. Their odd appearance is their best feature; their function is even worse. There are several brands of knuckle couplers out there. All are at least pretty good and all will work together pretty well except when trying to couple on a curve. The Kadee brand is the oldest and the best. But even knuckle couplers can have problems. The first thing to check is that the couplers are mounted on the car bodies, not on the trucks (wheels). Then check to ensure that the couplers themselves are at the proper height and that the curved wire hanging below the coupler just barely clears the railheads. The NMRA gauge will help with this, too. Then make sure that the couplers center themselves but are able to move back and forth as needed.
Trucks: It's not the trucks themselves which may be a problem. Rather, it could be that the couplers are mounted on them or that the wheels on the trucks are out of gauge. I already mentioned the coupler-on-truck matter (these are called Talgo trucks). You can use the NMRA gauge to check the spacing (gauge) of the wheels. This is very important. If the wheels are out of gauge, you can almost always correct the problem by twisting the wheels while exerting some force to push them closer together or farther apart. The odds are that your wheels aren't crazy out of scale but, if they are, try to keep the wheels an equal distance from each end of the axle. You probably don't have to worry about that but you don't want the situation where the wheels on one axle are closer to one end and the wheels on the other axle are closer to the other end of their axle. That can cause the truck to twist and get off of the rails. The last things to check with your trucks are that the wheels spin smoothly and easily, and that the trucks themselves pivot easily around their mounting screws. Most model railroaders find that one truck which turns readily but doesn't rock much and a second truck which both pivots and rocks works best. Tighten both trucks until they only pivot easily and then back one screw out a quarter to half a turn.
Weight: Cars which are incorrectly weighted can have trouble staying on the rails. It's far more likely that your cars are light rather than heavy. Heavy cars at the leading end of a backing train can increase the chances of a derailment but, again, you are much more likely to have underweighted cars. The NMRA standards say that HO rolling stock should weigh one ounce plus one-half ounce for every inch of length. For a 40-foot boxcar (pretty much the rule until recent years when cars began to grow longer and longer) that means about 3.5 to 4.0 ounces. Cars which are too light can be pushed up and off of the rails, especially if there is resistance to a train which is backing. Look closely at the way your trains' wheels meet the rails. You'll see that the wheel faces are not flat and completely on the rails. Rather, they are tapered just a little. That's great for reducing rolling resistance, but that taper can work to increase derailments when the car is being backed against a resistance, like the tail end of a train.
Overweight cars can cause problems, too. Specifically, they can push down on the rails hard enough that they don't want to move easily. If they are behind a string of underweight cars on a curve there is a good chance that the underweight cars will "clothesline," i.e., be pulled off of the rails to the inside of the curve. Similarly, overweight cars at the end of a backing train can cause increased resistance to motion, causing light cars to bunch up and jump off of the rails. So check your cars' weights. Let us know if you need to add weight and somebody or several people will tell you how to do that.
Speed: Most model railroaders learn quickly that "seeing how fast it will go" pretty much guaranties a derailment. This is really true when backing. Speeding backwards through a turnout is the single best way I can think of to have a train wreck. While that can occassionally be fun, it's awfully hard on the models so we don't speed with our trains, at least not very often. Please note: I'm not accusing you of running your trains too fast; I'm just pointing out the potential problem.
Well, I've written way too much but I have covered the possible problem areas. Hopefully, this will correct your derailment problem, or at least help you diagnose it. Don't hesitate to seek more information here if you need more help. Good luck, and have fun with your trains.
-- D
