Kato AC4400 finicky prone to derail????????

[da_kraut]

Hello,

I was running some freight trains on my layout when I noticed that from all of the Kato engines the AC4400's are very prone to derail.  Just by turning the engine 180 degrees while remaining in the same location in the consist and running in the same direction can solve the derailments from a particular locomotive.  

Has anyone else had the same experience and how did you overcome the problem?  Does something have to ge filed away for more movement or play for the axles?  I would appreciate any suggestions and by no means is this topic put on here to bash Kato.

Thank you

Frank 

[Medina1128]

If a particular unit is prone to derailing, I always check:

1. Make sure the wheels are in gauge. You DO have an NMRA gauge, don't you?
2. Make sure the trucks swing freely, and have some, not much, vertical play.
3. If checking the above does not fix the problem, I'm inclined to think that you're issue is with the track.

[CSXDixieLine]

Not sure what scale you are talking about, but I have many (too many according to the wife) N-scale Kato AC4400 and SD70M/MAC models. Also I have lots of various Atlas (GP38, B23-7, etc.) models. On my layout, which is an oval plus passing track arrangement, I have one spot where ALL of the Kato SD70MAC's derail 100% of the time while none of the other Kato/Atlas models (including the Kato SD70M's) ever derail. It is at a soldered flextrack rail joint and I suspect my trackwork here needs a redo, although it is funny that the one model derails always and the others never do. I am really just using this layout for experimentation, so I have yet to research this problem very far. Jamie

[trainfan1221]

I have the model in N scale and have no problems with derailing.  On my layout that's pretty good since I don't have very large curves, just 22".

[locoworks]

i'm wondering if it is in a consist whether the couplers used on the loco or what it's coupled to allow enough side deflection to allow the loco to stay on the rails? ( i'm in N gauge by the way )  the only loco i had trouble with at a track join on a curve was the PA1 from kato as it has such a long wheelbase on the bogies themselves.   although many loco's give 10/12 inch minimum radius, i now try and keep above 15 with 18 being the desired minimum.  if the loco derails on its own, i would check back to backs and also the side swing of the bogie, there could be a moulding pip or bit of flash somewhere causing the grief.

[selector]

If it tracks one way and not the other, I would suspect that one of the axles, probably the lead, in the direction of travel on the offending truck, is not true.  While the wheels may be spaced properly, and thus in gauge, they are both offset on the axle so that it forces one of the wheels to ride up, or pop out, and then take the rest of the truck with it.  It may be any or the axles, I suppose, but I am guessing it's the lead truck?

[da_kraut]

Hi

Thank you for all of the replies, certainly got me thinking a lot.  The scale is HO, the swithes are the large radius peco switches and the units are usually the second or third from the front while pulling a 30+ freight train on 36 inch radius curves.  Checked the switches with the NMRA gauge and they are fine.  

The trouble is that the layout is modular and when the modules were build there was no real testing and everything was ballasted in right away.  So this will be a messy rip, tear and rebuild event but first the locomotives will be inspected for the axles being in gauge and lateral truck movement.

Thank you for all the great suggestions

Frank 

[Don Gibson]

Herr K:

I suspect couplers (if it isn't wheel gauge or track).  "22 inch radius" would be close to 44" in 'N'. Plenty wide - even for 85' passenger.

WHAT happens if you run those offending  engines separately (uncoupled)?

TAKE each offending engine (and car) separately over the derailing spot, eyeball it, and report back.

It could be wheel flanges picking the frog as David B. thinks. I dont know if N scale products use NMRA wheel contours or recommended weights. I DO know Peco uses 'curved' frogs (and metric). Have you tried a Kato turnout?

OBVIOUSLY your wheels are not following the track.

[da_kraut]

Hello everybody,

Thank you for all the thoughtful replies.  They have been of great help.  Just spend another two hours fiddling with the track and peco switches.  As mentioned the NMRA track gauge came in very handy.  Finally got the AC4400's to run without incident.  It took a lot of tweaking but everything is fine for now.  The frustrating part is that the Kato GP35, SD40's, old run of SD40-2's, new run of SD40-2's, SD45, SD70's, SD90/43's, 44-9, P2K's, IHC Steamer, Athearn Blue Box, Athearn RTR and Atlas engines all run without incident.  Just the Kato AC4400's from which there seem to be two that are more prone to derail out of the four.   So I figure it is time for some surgery with a file on the offending engines themselves.  

Again thank you for the info, the next layout will be build on a rock solid frame work and the main line will be flat except for the helix that connects the two or three levels.  Figure that will eliminate all the problems.

Frank 

[trainfan1221]

AS an update to my previous post, I was running this engine last night.  No derailment problems but it has a front wheel that appears to be skipping as though there is a gear malfunction.  I have had this problem with Atlas and Kato.

[da_kraut]

Hi,

the current plans are to take the locomotive that runs without issues in both directions and measure it with a set of calipers.  These values will then be compared with those of the three offending units.  If any modifications need to be made then so be it.  Also the NMRA track gauge will be called upon to again check the axles.  The hope is that this will reveal the source of the problems.  David B, if you have any thoughts on what else might work aside from the mentioned suggestions please let me know.

If anybody has had similar experiences it would be great to hear from them.   Any input is valued information.  One thing is for certain the next layout will be build a bit different.

Frank 

[jeffrey-wimberly]

I had a similar problem with a Proto 2000 PA1. It was prone to derailing on ALL left hand turns. A careful examination revealed that the front of the front truck was lifting slightly going into the curve, only on left hand curves, never on right hand curves. The problem turned out to be one of the wires on the lead truck was too short and was pulling the front of the truck up. Putting in a longer wire solved the problem.

[railroadnut675]

Does it have a history of derailing?

[locoi1sa]

  Da-***

 The flangeways on the Pecos would be the culprit. I also have several mods and had to shim most of the right hand and a few left hand flangeways. Just a .010 styrene shim glued to the guard rail will cure your problem. The long wheel base 3 axle trucks are very prone to pick the frog. I could run anything else thru the turnouts even 2-10-4 steamers and artics without a prob but any 3 axle diesel will pick the frog at random.

      Pete