6 axle athearn sd-40-2 keeps on derailing

Discussion in 'HO Scale Model Trains' started by mikebalcos, Aug 27, 2006.

  1. mikebalcos

    mikebalcos Member

    i have an athearn sd40-2, but the front axle keeps on derailing at 18" curves. :( my guess is that my tracks are a little misshaped already (and that because i do not nail my tracks on my layout; i want the layout to be still modifiable since it is still pretty simple). are 18" curves the minimum for my 6 axle sd40-2? my 4 axles do not have a problem.

    oh btw, just to confess, my other 4 axles include 2 F7As and an athearn rdc. so i was preferring 1960 era engines. but my dad got me this sd40-2, and i'm not strict on the eras. i would love to see this sd40-2 running along the track. :)
  2. Jim Krause

    Jim Krause Active Member

    Have you tried running the SD40 with the B end forward to see if it does the same thing? (The B end is the end opposite the cab). If the same thing happens, it may be the track. If not it could be wheel spacing on your front truck. Do you hace a wheel gauge?
  3. mikebalcos

    mikebalcos Member

    thanks for the tip jim. i never thought of that. :) i'll try it now. btw, thanks for explaining the b end. i didn't know that either. i guess i'm pretty dumb about these things. hehe. ;) i'm still a beginner about these things.
  4. mikebalcos

    mikebalcos Member

    i've just tried running it with the b end forward. and yes, the leading axle also derailed. i guess it is the tracks. :(
  5. AndyWS

    AndyWS Member

    I too have an Athearn SD40-2, Chicago & Northwestern #6935. It absolutely LOATHES 18" curves. When it goes into a curve it makes a loud grinding noise that sounds as if the mechanism is binding up, which goes away once the track straightens out again. In fact, out of my six locomotives with 3-axle trucks (C-C or A1A-A1A) only my Athearn Fairbanks-Morse H24-66 Trainmaster seems to have no difficulty with 18" curves.

    I wasn't a member during the "Diesel of the Week" thread featuring these locomotives, so I'll post its picture here. It is unfortunately permanently relegated to the roundhouse until such time as the layout is expanded and the curves eased.

  6. mikebalcos

    mikebalcos Member

    nice picture. mine is with the union pacific colors. i'm a bit shy to show mine, since the horn is already missing. :(

    would these muscle bodies fare well on 22" radius tracks? i guess that's the most liberal curve track from atlas (from which i prefer getting tracks).
  7. alexander

    alexander Member

    Yes, i'm pretty certain that they would handle 22" curves well. Heck, i reckon you could put them on 20" curves
  8. mikebalcos

    mikebalcos Member

    thanks for the info, alexander. :) will a full 22" curve fit in an 8x4? i think it would, but i'm not sure. my collection only has 18" curves and straight tracks, but i think i will buy 12 22" tracks so that i could build an oval for the athearn sd40-2. :)
  9. alexander

    alexander Member

    A 22" curve will fit on a 4x8, but it would easily fall off, you would have alomst no clearence to the edge. I would reccomend having a barrier of some sort to block trains from falling to the floor
  10. yellowlynn

    yellowlynn Member

    One other reason your 6 axle loco is derailing is that the trucks may not turn enough to follow the tracks. That could be the same on either end. Just check how much the trucks can turn.

  11. cidchase

    cidchase Active Member

    If the trucks rotate enough to acommodate the turn, what about removing the flange from the center wheels?
    I know some steamers (models) are built this way because of the wheelbase. I think it
    would hardly be noticeable on a six axle diesel.
  12. alexander

    alexander Member

    The SD40 can go aroud a 18" curve

    Another thing to check out is wether your Trackwork is as good as it can be

    I'll close by saying that on my layout, whch had bad trackwork, my SW1500, Athearn wouldnt even get out of the spur, yet my (well it was on loan from a club) SD40-2 almost made it around the whole layout

  13. LongIslandTom

    LongIslandTom Member

    I have four Athearn blue-box SD40-2s... Had them since 1988. I don't run them much though, because I don't have much room and am restricted to using 18" curves. I found that having a bit of bank (superelevation) on the curves do help keep them on the tracks. They do stay on the rails with the bank, but the pilot overhang do tend to exert a lot of lateral force through the couplers and can derail cars being pulled by the engines.

    For that reason my 4-axle Geep fleet is far larger-- 22 of them, all Athearn BB's. :D
  14. alexander

    alexander Member

    Yeah, its pretty much accepted that if your going to run 6 axle motive power, it will have overhang and ont look pretty

    BTW, if you really want big power, the Atlas SD24 handles 18" easily, it doesnt look that bad on them
  15. brakie

    brakie Active Member

    Long wheel base 6 axle units and 18" curves are not the best combination.Best to use larger curves for these types of 6 axle units.You see that SD40-2 is a scale 68 ft 10 in.On the other hand a SD24 is 60 foot 8 inches and that scale 8 foot 2 inches can make a difference in the size of curves these units will take.
  16. alexander

    alexander Member

    Yes, your right there, ths SD40-2 is longer than my SD24, but the SD24 Looks like a big unit, compared to a GP7.

    It seems that the more modern time periods have longer locos, while pre 1980 is a lot shorter, save for the E Units, etc
  17. brakie

    brakie Active Member

    And just think you can hide that SD24 behind a 60 foot boxcar! sign1 And that SD24 was a long unit in its day.Btw..You can hide a E8 behind a 73 foot center beam..:eek:
  18. alexander

    alexander Member

    I knew E Units were long, but i never thought that long

    BTW, not to rain on your parade, but the SD24 is 8 inches too long. lol
  19. brakie

    brakie Active Member

    A E8 was 70'-3"..A long handsome lady if you ask me that could zip along at 85mph...:D
  20. alexander

    alexander Member

    hmmmm, 85 MPH. A respectable speed, yes, but i've seen faster

    How did these specs compare to other E units, F units and GP/SD series locos, if you know?

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