Class 25/33: Step 14 – Running In & Body Fitting

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  • If you have a multi-meter then use it to check the current of your re-built locomotive. Current draws vary, but anything below 150mA should be acceptable. I personally aim for lower, but don’t be disheartened if it is around that level. Small diesels with a “good” armature can achieve current draws as low as 80-90mA if rebuilt well. Older 3 pole motors tend to have a higher current consumption. If your current draw after a rebuild is much above 150mA then be wary that you might have a faulty motor. Check for heat – indeed always check for heat during running in, as this can be a sign of a short in the motor or excessive friction somewhere in the drive mechanism.
  • If you plan on running in the locomotive then leave the body off for now. Running in should preferable be carried out on track with curves so that you can observe any issues (certain symptoms show up when a locomotive is on a curve). Another option is to use a rolling road, as picture 2 illustrates. I am a big fan of these and they are helpful if you only have an end-to-end piece of track. A worthy note, however; rolling roads will not highlight any cornering symptoms and can also accentuate any lateral “wobbles” which wouldn’t occur on the track. Running in has the benefits of allowing the mechanisms to “bed down” and for the carbon brushes to shape themselves onto the commutator through wear.
  • To fit the body, refer to picture 3 above. Slot the body over the chassis at one end and then push the other end down. This should be a very simple task.

Note: Monitor for heat when running in your locomotive. I suggest a running in period of 30 minutes in each direction, perhaps checking for heat after the first 10 minutes of running in each direction. If there is excessive heat (you cannot avoid all heat) then stop the running in, since this is a symptom of a problem and could lead to further damage if you persist with the running in. Additionally, if you have carried out a current reading before running in and found it to be excessively high, do not proceed with the running in, since heat will most likely be generated.


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