HO scale Hallmark AT&SF M-190 question

Skyraider Jan 19, 2023

  1. Skyraider

    Skyraider TrainBoard Member

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    The brass M-190 that was imported by Hallmark has a pretty poor reputation in regards to running quality. Have any of you had one? Were you able to make it run well?

    Thanks in advance.
     
  2. Mr. Trainiac

    Mr. Trainiac TrainBoard Member

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    There are some youtube videos of this model, and they seem to be relatively smooth. You can hear some gear noise, a lot more than a modern plastic model, but they look to run decently well. Other than the standard brass modifications and upgrades, I would attempt to replace the drive with a Proto 1000 RDC as a last resort if you can't get yours to work.

    The Proto 1000 RDC is outside-bearing, so swapping the sideframes is pretty involved. I wouldn't attempt it unless you had a 3D printer or are confident in scratchbuilding trucks. The brass pickup strip is load bearing in a similar manner to Athearn Genesis HTCR trucks. It mounts to the sideframe, which then mounts to the gearbox.
     
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  3. Skyraider

    Skyraider TrainBoard Member

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    Thanks for the great info. Being a Santa Fe fan and living in West Central Texas, it would be fun to have one. There are a couple for sale I know of but both say "does not run." A friend who has worked on brass locomotives for decades told me once that he had seen quite a few that didn't run well. Considering your input, I may steer clear of them. Scratch-building structures is one thing, but truck sideframes is a completely different ball of wax. Do the proto 1000 trucks have the same broken gear issue that proto 2000 locomotives tended to have? I've changed quite a few of those.

    Tenshodo used to make a free standing power unit that might work as a replacement, but they're pretty hard to fine.

    Again, thanks for the input.
     
  4. Mr. Trainiac

    Mr. Trainiac TrainBoard Member

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    My RDC does not have any split axles. The Proto RDC looks like it copies a Kato mechanism, rather than the Athearn clone other locomotives used. In theory, the axles could split since they are still metal half-axles on a plastic shaft, but I haven't seen it mentioned prevalently online.

    Stanton drives from NWSL may be another option. I don't know the wheelbase or wheel diameter of the power truck on M-190 though.

    Here's an M-190 in custom paint: Sounds a bit loud, but looks like it runs smooth enough. This is probably a realistic expectation for your model. Swapping the open frame for a modern can motor, shimming any play in the worm shaft with washers, and replacing the rubber tube with a universal joint would probably go a long way to making them run better. If the price is right, those non-running models could be a fun project.
     
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  5. Skyraider

    Skyraider TrainBoard Member

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    Thanks, again, for the info. By the way, the reason most gears split is that the gear is made of a material called acetal resin (delrin is an example). Delrin, and others like it, have what's called a half life--they shrink over time. The amount of shrinkage is halved each year. If the hole in the gear is too tight on the shaft, after some shrinkage it will split. Some other plastics don't do that. If the delrin is annealed, it will be less likely to change shape, shrink, crack, etc.
     

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