Atlas/Kato U25B Shell Removal

atsf_arizona Jan 21, 2017

  1. atsf_arizona

    atsf_arizona TrainBoard Supporter

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    Hi, folks,

    Having trouble figuring out how to remove the shell on one of the original Atlas/Kato U25Bs (yes, the circa 1988 issue). Thought maybe some of you here on Trainboard.com's N scale forum could give some advice.

    I'm finding out for this loco, it's not so simple.

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    1) Clearly, the "tap the end of shell on tabletop" technique does not work, as there are shell locking tabs in the shell that lock into corresponding indents in the U25B mechanism (I discovered that when working removing the shell on the Atlas Classic U25B version):

    [​IMG]
    http://www.pbase.com/atsf_arizona/image/164708350.jpg


    2) Railwire / Ron Bearden's tips for this shell removal ..... have been mysterious to me, haven't been able to get his suggestions to work, can't get the rear of the shell to release..... : https://www.therailwire.net/forum/index.php?topic=30702.0

    3) Atlas U25B Atlas/Kato Japan instruction sheet - also similarly "mysterious", I can't figure out what they meant by removing the cab (maybe get to the locking tabs under the cab? But then what about the rear tabs?) : http://www.atlasrr.com/pdf/N GE U25B Loco-Japan.pdf

    4) Spookshow's website: http://www.spookshow.net/loco/atlasu25b.html and the shell removal tips haven't worked for me either, my shell seems to not give way or move when trying his 'screwdriver tip' suggestions. Finally, he Spookshow webpage shows that there is a "lip" on the Atlas/Kato U25B mechanism:

    [​IMG]

    which prevents me from directly getting in there to release the shell locking tabs that I identified in the Atlas Classic U25B picture above.

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    I'm sure there must be many of you out there who, over the past 28 years since this Atlas/Kato U25B was released, that have found the "secret" to safely removing this shell.

    Appreciate any hints / tips / experiences. Thx.

    Sincerely,
     
  2. bremner

    bremner Staff Member

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    I gently pull the handrails out of the cab first, then pull gently on the shell. Sometimes you need to push up near the pilot on the bottom of the walk
     
  3. SecretWeapon

    SecretWeapon TrainBoard Member

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    hey John, I squeeze the long hood separate it from the walkway. Of course like said earlier, pop off the handrails on the cab. Then work the walkway up. It's tight. So go a little at a time. If you're going to change shells, Kato-Atlas, you have to use the walkway of the chassis. The shells are interchangeable.
     
  4. atsf_arizona

    atsf_arizona TrainBoard Supporter

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    Hi, SecretWeapon, bremner, thx.

    OK, I managed to get the shell off. Like Spookshow said at his website: http://www.spookshow.net/loco/atlasu25b.html ... I had to use a screwdriver and (gently but firmly) lever the shell off. It was tight, the shell was bending a lot, I had reached the point where I had to be willing to "break the shell and then repair it" in order to learn and how to get this shell off.

    The first time is always the hardest; now I know what's inside and where. When I get some time soon, I'll take and post some pictures, so that we have documented, what the inside of this shell looks like, where the mounting tabs are, what I had to do to get the (very tight fit) shell off. Give me a few days to get back to that.... thx.
     
  5. mtntrainman

    mtntrainman TrainBoard Supporter

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    File the tabs on the shell down a bit. File the 'nubs' on the frame down a bit. It will make it easier next time...;)
     
    SecretWeapon likes this.
  6. atsf_arizona

    atsf_arizona TrainBoard Supporter

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    mtntrainman, agreed. I'll do that after I take the photos of the 'as-stock', so that we can also see the before and after. :)
     
    mtntrainman likes this.
  7. atsf_arizona

    atsf_arizona TrainBoard Supporter

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    I am finally making progress on documenting removing the Atlas/Kato and Atlas Classic U25B N scale shells. Have taken some pictures and will (eventually) get to posting them here. But in the meantime, here's a few words:

    Basically, this particular locomotive, because of it's original Atlas/Kato heritage and the late 1980s timeframe that it was designed (the Atlas/Kato versions came out in May and November of 1989), have a set of tabs that lock into slots in the split-frame mechanism sides. Other Atlas/Kato designs dating to that era (RS1, RS3, etc) also have this style of locking tabs.

    Starting around the U30C and SD40 Kato designs, and the Atlas/Kato SD7/9 and Atlas/Kato GP30 and GP35... thankfully those shell designs did away with locking tabs, and just relied on the "nubs" on the side of the mechanism to fit into associated depressions in the inside of those shells... works just as well and uber-easy to remove the shells via the "tap" method.

    But now... back to this design of the U25B shell / walkway with tabs, and how to get the shell off:

    [​IMG]
    http://www.pbase.com/atsf_arizona/image/164708350

    ==> I will need to modify the picture above to *remove* the reference to the "toothpick" technique - I found that *didn't* work reliably.... too easy to bend the copper pickups going to the trucks on the Atlas Classic U25B.... sorry..... you can figure out how I know that..... :(

    ---------------------------

    Because of these locking tabs on the walkway, my method that I've worked out and used successfully (using the tips by SecretWeapon above - thx!) is now as follows:

    1) Remove the hood part of the U25B shell first, separate from the walkways
    2) Then, you can much more easily work the U25B walkways off by themselves

    This applies to both the Atlas/Kato U25B's, and the Atlas Classic U25B's.

    Re-installation is the reverse - I put the walkways back on by themselves, then put the hood shell back on.

    Here's a verbal step by step:

    1a) remove the cab hand rails from their slots in the front rear of the cab
    1b) from the rear of the U25B shell , very gently use a small jeweler's screwdriver to separate the hood shell from the walkway. Then lever and push up the hood shell from the rear, leaving the walkway in place.
    1c) working my way forward, keep levering the hood shell upward gently. It will come away from the walkway (the walkway is still locked down due to the retaining tabs in the picture above)
    1d) as you get close to the cab, make sure you already did step 1a, i.e. remove the walkway handrails from the cab slots. If you haven't done that, do that now. Assuming that's done, there are two retaining tabs at the rear of the cab, that lock the cab to the walkway. Gently levering both the shell and cab upwards, you'll be able to release those cab tabs
    1e) once the cab is released, you're almost home free. keep levering the hood shell upwards from the rear until....
    1f) you finally will get to the nose of the hood shell. Gently pry the hood shell upwards, *separate from the walkway*, from the front
    1g) if all goes well, the hood shell will come free.... with the walkway still on the mechanism.
    1h) Now, you can easily see / access the walkway locking tabs on the walkway, shown in the picture above (on the Atlas Classic U25B you couldn't see / access them easily before with the hood on and could too easily bend the copper power pickups going to the trucks... and on the Atlas/Kato models, there's a metal part of the mechanism preventing you from access the tabs from below anyway).
    1i) Now you can gently spread those walkway's tabs apart, and gently start levering the walkway up from the mechanism. I start from the rear again, seems to be easier to access and spread the tabs there first.
    1j) The next tip.... the walkway is a very tight slight interference fit on the *ends* of the mechanism. I need to gently lever the walkways up "level", so that I can "stretch' the walkways just enough to lever them off the ends of the mechanism. Look for interference fits, or MT coupler conversion adapters, that are "hanging up" on the ends of the mechanism. Work carefully here and eventually you'll be able to work the walkways off.

    After 1j), I file down the ends of the mechanism and inside of the walkway ends a bit, so that future removals will not be so tight.

    Installation is the reverse - I put the walkway on first, then replace the hood shell.

    I hope this helps. Pictures coming... eventually. If you have a urgent need to see the pic's because you're right in the middle of a project, post below and I'll try to accelerate my prep of the picture posting.

    Hope this helps. :)
     
    Last edited: Apr 30, 2017
  8. Hardcoaler

    Hardcoaler TrainBoard Member

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    As an older N Scaler, the modern-day puzzle of separating shells from various chassis is unnecessarily complex and frustrating. Why is it so painful for manufacturers to instead use two screws? :mad:
     
  9. Hardcoaler

    Hardcoaler TrainBoard Member

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    Does anyone know if the Atlas U-23B shell will fit on the Atlas (as manufactured by Kato) U-25B Chassis? I think the prototype's coupler facing and truck spacing were the same on the U-23B and U-25B. Both shells attach to the chassis with the four small nubs/bumps. I'd have to chop the Rapido coupler boxes off my old U-25B trucks to fit the Atlas U-23B shell with its built-in Accumate couplers, but that's okay. Thanks.
     
    BNSF FAN likes this.

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