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  • Topic: Posts on SD70 for coupler have broken off.

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    • June 29, 2020 10:39 PM EDT
      • Seattle, Washington
         
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      Posts on SD70 for coupler have broken off.

      One of my USA Trains SD70 engines has had the posts on the front of the body break off that hold the coupler in place. I can put bigger screws in to hold it, but I can't put longer ones as they would pierce through to the top which is a walkway.  Suggestions on how to go about fixing this? I had the USA Trains coupler on the engine.   I do not have original screws or the posts that broke off.  I do have the part that screwed in though and the coupler itself.   I have attached a second photo showing what it should look like with the posts intact.

      This post was edited by Nicolas Teeuwen at June 29, 2020 10:44 PM EDT
    • June 29, 2020 11:09 PM EDT
      • Sherwood Park, Alberta
         
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      Nicolas,

       

      I just had a look at mine. If you remove the walkway plate that sits over it, you should be able to drill right through, install new rods, and once they are nice and dry, drill holes for screws. It looks like you would need around a 3/16" rod.

       

      Shane

    • June 30, 2020 12:14 AM EDT
      • Seattle, Washington
         
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      Cool.  Thanks Shane.  I just took it apart and was able to take the walkway plate off.   Nice to know i won't accidentally drill through the walk way plate and can cover up my fix later.  Suggestions on where to get plastic for the new rods as well as glue for them?  Is it better to drill through or just drill deep enough that the new rods have a pocket to sit in?  There's not a lot of material to work with in this spot. 

    • June 30, 2020 12:46 AM EDT
      • Sherwood Park, Alberta
         
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      Hi Nicolas,

       

      If it was me, I would drill right through. That way you will get some extra strength. If you have a hobby shop close, they should have a selection of evergreen rods. I was just guessing with the 3/16. You may want to push a drill bit through the hole in the coupler mounting bracket to see the exact size you will need. I've had pretty good results using Plastruct Bondene for attaching styrene to locomotives. You'll have to be careful to drill your hole straight so that you get a nice tight fit with the rod.

       

      Hope this helps.

       

      Shane

      -sorry-fixed typo on Plastruct

       

      This post was edited by Shane Stewart at June 30, 2020 12:59 AM EDT
    • June 30, 2020 10:18 AM EDT
      • Maryland
         
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      Same thing happened to my USAT NW 2.  Post broke off, they seem to be susceptible  to bending moments, or harder then I would like hits while coupling up, and the like

      I epoxied my back and that lasted for a few years, then they broke again.  I just keep doing that but a better solution would be appreciated. Probably a through bolt, painted to match the decking is the right answer for me.

       

      Jerry

    • June 30, 2020 11:40 AM EDT
      • Easton , Massachusetts
         
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      Has any one 3d printed a box that could be epoxied under the decking ...hmm

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    • June 30, 2020 2:23 PM EDT
      • Seattle, Washington
         
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      I am pretty sure mine broke off a few weeks ago when one train hit another when i wasn't looking.   I have given up on the snow plows on the front of my SD70's. They were fragile to begin with, and I widened the coupler swing to support better operation on my tighter 10' curves.  I may actually drill small holes in the front wall and use small zip tie reinforce the coupler housing to prevent it from breaking off.

    • June 30, 2020 4:50 PM EDT
      • Deer Park, Washington
         
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      A few years back, someone produced a 3D Printer file for some USAT locomotives, to solve just this problem.  I installed a pair in my GP9 and SW4, and both are doing fine.  I wish I could remember who...

      This post was edited by Steve Featherkile at July 1, 2020 8:09 PM EDT
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    • June 30, 2020 7:33 PM EDT

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      Nicolas Teeuwen said:

      One of my USA Trains SD70 engines has had the posts on the front of the body break off that hold the coupler in place. I can put bigger screws in to hold it, but I can't put longer ones as they would pierce through to the top which is a walkway.  Suggestions on how to go about fixing this? I had the USA Trains coupler on the engine.   I do not have original screws or the posts that broke off.  I do have the part that screwed in though and the coupler itself.   I have attached a second photo showing what it should look like with the posts intact.

       

      Pretty sure you're RR is a standard with USA couplers which is fine as it suits your RR needs.  I'm pretty much moving over to Kadee's on my end and did a nice SOLID sill mounted Kadee on my one SD70 the other was purchased with ...never mind

    • June 30, 2020 7:34 PM EDT

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      Shane Stewart said:

      Hi Nicolas,

       

      If it was me, I would drill right through. That way you will get some extra strength. If you have a hobby shop close, they should have a selection of evergreen rods. I was just guessing with the 3/16. You may want to push a drill bit through the hole in the coupler mounting bracket to see the exact size you will need. I've had pretty good results using Plastruct Bondene for attaching styrene to locomotives. You'll have to be careful to drill your hole straight so that you get a nice tight fit with the rod.

       

      Hope this helps.

       

      Shane

      -sorry-fixed typo on Plastruct

       

      Evergreen tubing is an option as well.

       

    • June 30, 2020 11:33 PM EDT
      • Vail, Az
         
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      I'd look into a bar across the bottom of the post with an angle to the frame

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    • July 1, 2020 7:09 PM EDT
      • Seattle, Washington
         
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      Solution I went with: 4-40 3/4 inch long flat head screw.
       
      1. Remove top shell, or you can't do step 2.
      2. Remove walkway plate and circuit board
      3. Drill holes that screws went into with a 3/32 bit. Just a bit smaller than the screws.
      4. Purchase 3/4 inch long 4-40 screws, nuts, and #4 washer.
      5. Counter sink the holes on the top side so the screws will sit flush with the frame.
      6. Screw in the 4-40 screws until flush with top.
      7. Put on coupler bracket, Loctite, washers and nuts and screw til tight.

       

      The coupler needs more sheer strength then vertical strength. In order to sheer off the coupler now, the coupler/front of the locomotive would have to be hit with enough force to sheer off the screws, or pull the screws through the frame. At that point it will have likely sustained a lot of damage from the force of the hit and the coupler will be the least of the problems. The only downside of this solution is that to remove the coupler bracket, one has to do steps 1 and 2 which is a lot of disassembly. I used stainless hardware.

      This post was edited by Nicolas Teeuwen at July 1, 2020 7:09 PM EDT
    • July 1, 2020 7:52 PM EDT

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      I would love to see a picture of this

    • July 1, 2020 8:17 PM EDT
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      Sean McGillicuddy said:

      Has any one 3d printed a box that could be epoxied under the decking ...hmm

      I made this one recently for the SD40-2 frame.  It's pretty similar.  I wonder if it will fit.

       

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    • July 1, 2020 8:48 PM EDT
      • Seattle, Washington
         
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      I have the piece that USA Trains installed that would be equivalent to this.  Its the posts that hold it on to the frame that broke. The small ones that would fit in those two holes.
      Dan Gilchrist said:
      Sean McGillicuddy said:

      Has any one 3d printed a box that could be epoxied under the decking ...hmm

      I made this one recently for the SD40-2 frame.  It's pretty similar.  I wonder if it will fit.

       

       

    • July 1, 2020 9:33 PM EDT
      • West Glocester, Rhode Island
         
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      Right.  My design would be best if you were willing to glue it as it makes good solid contact with the pilot.  Isn't the stock mount just a "U" bracket?

      Nicolas Teeuwen said:
      I have the piece that USA Trains installed that would be equivalent to this.  Its the posts that hold it on to the frame that broke. The small ones that would fit in those two holes.
      Dan Gilchrist said:
      Sean McGillicuddy said:

      Has any one 3d printed a box that could be epoxied under the decking ...hmm

      I made this one recently for the SD40-2 frame.  It's pretty similar.  I wonder if it will fit.

       

       

       

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    • July 1, 2020 9:47 PM EDT
      • West Glocester, Rhode Island
         
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      Got me thinking

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    • July 2, 2020 3:18 PM EDT
      • Seattle, Washington
         
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      Here are a few photos showing how I did the install.

       

    • July 2, 2020 6:23 PM EDT

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      Looks great!

       

      Now that you have the tang securely mounted with the 4-40 what about the coupler itself ?

       

      Nice work!!

    • July 3, 2020 4:10 AM EDT
      • Seattle, Washington
         
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      The coupler itself was reattached as normal.  The only damage that happened was that the small posts sheered off and the screws disappeared.  In fact, it wasn't until I tried to pull something from the front of the engine that I even realized there was an issue. The coupler fell down. 

       

      As a side note, I have removed the springs from all my SD70 couplers, and widened the swing by cutting a notch in the frame so the couplers can swing further.  This eliminated issues with the couplers coming undone at certain points on my railroad.  The biggest issue i had was with two SD70's pulling a consist. The front one would often detach and take off leaving the second one to pull everything. I was able to tweak the track geometry in a few places to fix the issues but the connection was unreliable.   My conclusion, if pulling SD70's on 10' diameter curves, you are best to remove the springs and widen the swing of the coupler for better reliability.

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