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Hello, Back in December I bought a DD40-X model. At the time I only had 18" radius curves and the DD40-X didn't run well on these tight curves. When it was coupled to a train the front truck would spin while the rear truck would not even move. Recently I purchased enought 24" radius track for the out side track of my railroad. The DD40-X runs much better now, except when coupled the the same mixed freight train of about 20 cars it doesn't exactly the same thing. The front truck spind while the rear truck doesn't even move. If I lift the rear of the locomotive up just a little the wheels then begin to spin. The DD40-X has no trouble at all pulling my 12 car RoadRailer train. Does anyone know what may be wrong with my model and what I should do about it?
The problem you are experiencing is caused by two things. The first is the EXTREAM length of the locomotve. The model is almost 12 inches long and therefore needs large radius curvs to operate satisfactorily. The second, is the four axal trucks of the locomotive generate a very large wheel base. Bachmann has included prvisions for some lateral play to compensate, but the trucks are just binding up on the curves of your model railroad when it is under a moderate load, like your 20 car freight. The only way to correct this problem is to use broader curves. After Experiencing the same problem with an Athearn DD35 (listed in their catalog as a DD40 AX) I have found that these engins should not be run on less than a 30" radius Curve, with the optimum curve about 36" radius.
Tip: A way to determin the minimum optimum operating radius of a locomotive or freight car. Measure its length. Then multiply by three. That number is your minimum optimum radius.
Note: you do have a couple inches leeway in the downward direction though. Many engines are also designed to run on a minimum operating radius which is about twice the locomotive length. This is helpful for desinging your layout if you know what equipment you want to run.
Posts: 315 | From: Lander,WY USA | Registered: Jan 2002
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posted
For Optimum Performance Yes. Note However. Most companies design their products so they can run on samller radius track without much difficulty. Definatly would not go under 24" radius on any lengh passenger car though.
James Mitich Mitich Rail Limited mrljames@hrp.every1.net.
Posts: 315 | From: Lander,WY USA | Registered: Jan 2002
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