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Brass hallmark sd-7 shorting out on curves

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  • Member since
    October 2007
  • From: ohio
  • 1,371 posts
Brass hallmark sd-7 shorting out on curves
Posted by rs2mike on Saturday, October 18, 2008 4:23 PM

Ok I just got a steal on a hallmark brass sd-7($40.00)  Looks great and after a complete tear down and cleaning of the running gear and relube it runs awesome. 

Ran it all around the track with just the frame and motor and it ran flawlessly.  Trouble arose however when I fitted the body back on the frame.  When it comes to a curve it shorts out.  here is the assembly

Now the long hood is opposite the round air tanks and I noticed that when together the long hood truck seems to catch on something.  So I took it apart once more and fitted the body without the walkways and railings and this is what I found.
See where the pencil is pointing it is raised.  It can rock back and forth over some pivot point I cannot find.  This is what it looks like on backwards.  So any conclusions on what gives????

Thanks for the help

alco's forever!!!!! Majoring in HO scale Minorig in O scale:)

  • Member since
    May 2004
  • From: Conway SC
  • 222 posts
Posted by wmshay06 on Saturday, October 18, 2008 5:14 PM

While this is some what in the way of conjecture, it sounds like one one of both of the truck gear towers may be rubbing against the inside of the body shell when they round a curve.  I'd look for bits of wire/castings,etc on the inside that may need to be smoothed down.  Also rotating the trucks by hand after re-assembly might reveal something as well.

 

Charles

  • Member since
    February 2008
  • 8,877 posts
Posted by maxman on Saturday, October 18, 2008 5:46 PM

What does the assembly look like with the walkway/step assembly sitting on the bottom frame?  Put the walkway part on the frame and rotate the trucks by hand as was suggested above.  Check and see if the outer corners of the truck sideframes are hitting the inboard corners of the stepwells.

  • Member since
    October 2007
  • From: ohio
  • 1,371 posts
Posted by rs2mike on Saturday, October 18, 2008 5:50 PM

It does seem to catch but what is weird is when on backwards it does not catch on anything.  The truck towers are the same so I do not know what is going on.

 

alco's forever!!!!! Majoring in HO scale Minorig in O scale:)

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Saturday, October 18, 2008 5:50 PM

 Hands down it's the truck tower touching either the body or the cutout in the chassis. On less tight curves it probably would never touch.

              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    October 2007
  • From: ohio
  • 1,371 posts
Posted by rs2mike on Saturday, October 18, 2008 5:52 PM

I will try the walkway and rotate.  but it seems it is more in the cab than in the walkway

alco's forever!!!!! Majoring in HO scale Minorig in O scale:)

  • Member since
    October 2007
  • From: ohio
  • 1,371 posts
Posted by rs2mike on Saturday, October 18, 2008 5:53 PM

It barely makes it into the turn before it shorts out.  I could see halfway into a 20 in curve that that would be the case

 

alco's forever!!!!! Majoring in HO scale Minorig in O scale:)

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Saturday, October 18, 2008 5:58 PM

 The 'not fitting' part of the hood is probably a protusion from the fans catching on the top of the motor. When you put the hood the other way there's nothing on the shell at that location so it sits down where it's supposed to.

 You're right, it shoudl only short out if BOTH trucks are turned, since each truck only picks up from one rail, and each truck is suppsoed to be insualted from the middle part of the chassis - see those red washers? There should be some underneath too - if one of those has deteriorated it would allow the chassis to be 'grounded' to the truck with the bad insulator.

               --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    October 2007
  • From: ohio
  • 1,371 posts
Posted by rs2mike on Saturday, October 18, 2008 7:37 PM

Ok well when I had it apart the red washers on top and the white plastic inserts were in good shape.  like I said it runs great with the shell off so I guess I need to dig around a little more to see what is catching.

I don't think the walkway raises it up enough to take care of the gap problem or not.  i will have to dig further

 

alco's forever!!!!! Majoring in HO scale Minorig in O scale:)

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