Is it the track or the trucks?

[E-L man tom]

I have a pair of Athearn SD45's, in the Ready to Roll series. I wanted to test them out on my little switching layout, as I have recently completed the track work. So, with some tight curves and some No. 4 turnouts, I figured, if the track will be trouble free with 6 axle locos, the 4 axle ones, which I will primarily use here, should work fine. So I ran the SD45's, one at a time. The first one derailed on some turnouts, even No 6. and, on some of the turnouts that it didn't derail on, it went through them roughly. The second one I ran went through all turnouts smoothly - - trouble free. I have an Athearn Blue Box SD9 that I tested on the track and it too went through all the turnouts with no problems. The only 4 axle loco that I've tested so far that incurred any problems was my Athearn Blue Box SW7 (I call it an SW9); I have a host of other problems with it though, like getting decent contact with the track, so I know that I have some trouble shooting to do on that one.

So my question is:  Is it the trucks on the locomotive(s) or the track/turnouts? 

Any help would be appreciated. Thanks.

[BRAKIE]

E-L man tom

So my question is: Is it the trucks on the locomotive(s) or the track/turnouts?

Tom,I would check the trucks on the SD40-2 that is derailing..Off hand I suspect the wheels may be out of guage.

[Medina1128]

When I first got into the hobby in the 80s, I realized that unless you're running short wheelbase locomotives that the tightest turnout I'd ever use were #6s. I think 6 axle locomotives are a little too big for #4s. And, with the overhang, they just look funny.

[Lone Wolf and Santa Fe]

6 axle diesels should work fine on #4 or larger turnouts.
Things to check when trouble shooting:

Are all of the wheels in gauge compared to NMRA gauge? That can be a real problem as out of gauge wheels tend to derail on turnouts.

Is the turnout locked in place with a ground throw or switch machine? Or does it move when the locomotive goes over it? Usually if this is the case the rear trucks derail.

Does the turnout produce an S curve? That is a common design flaw of placing a turnout directly after a curve.

[riogrande5761]

6 axle diesels should work fine on #4 or larger turnouts.

I'm with Marlon.

I'll just say as a teenager I had an Athearn blue box SD45 and it didn't like the #4 turnouts I had, and derailed.  Due those memories, I decided to make #6 turnouts (at that time #5 turnouts were not common) my standard yard turnouts and my current crop of SD45 seem pretty happy with those. 

Personally, I wouldn't go less than a #5, but thats me.  I tend to be conservative, risk averse prefer to stack the deck in my favor.

 

[selector]

If the turnout is flat....dead flat....with no high spots or sags near the frog........

If the points rails sit tight and very sharp against their stock rails....................

If the guard rails have an NMRA compliant path for the flanges on the wheels...

If the wheels are in gauge..........................................................................

If the wheels are equidistant to the pointed ends of their axles........................

If the axles are properly seated...................................................................

If the trucks can pivot the same in azimuth...both left and right, and have some up and down movement that doesn't have them running up against details or something................................................................................................

.................then I have no idea.  Sorry.

[ATSFGuy]

Everytime on of my trains derails on the club layout, I blame the module owner for not providing adequate track maintence.

It's easier to blame the track than the train. 

[E-L man tom]

Well, I did some checking of the track with my NMRA guage (I haven't checked the wheels yet) and found that in the most common trouble spots, that the track is out of guage (too wide). The question is:  how do you correct that? I'm using Atlas code 100 flex track.

One other thing, I have two Life Like P2K SD7's that also derail, not on turnouts, but on one of the spots that the SD45 derailed on; it is coming out of a superelevated turn. The track is out of guage in this spot (again, too wide), but it also comes out of the superelevated track while still in the turn. Just wondering if that has anything to do with the problem.  

[Graham Line]

I'd take a serious look at extending the transition zone from super-elevated to level track. Double or triple the transition distance and I'll bet that trouble goes away.

You don't say where you found the wide gauge segment. My guess with Atlas is that it's somewhere in a switch and you can correct it by shimming the flageways into speck with shim brass or .005 or .010" styrene, depending on your contact needs.

[selector]

How out of gauge is "out of gauge?" 0.5 mm?  0.8mm?  1mm? None of those is likely to cause a derailment, even on a curve unless it's about 1mm too tight...or more.  If too wide in gauge, the typical HO scale wheel with its wide tread is not likely to derail.  Instead, I have found that derailments on curves, especially those super-elevated, tend to be due to uneven rail heights across from each other relative to the axis of movement.  A dip in an outside rail on a super-elevated curve is lethal in our hobby. Even a fraction of a mm can make a big difference, as I have learned harshly several times.

[E-L man tom]

selector

How out of gauge is "out of gauge?" 0.5 mm?  0.8mm?  1mm? None of those is likely to cause a derailment, even on a curve unless it's about 1mm too tight...or more.  If too wide in gauge, the typical HO scale wheel with its wide tread is not likely to derail.  Instead, I have found that derailments on curves, especially those super-elevated, tend to be due to uneven rail heights across from each other relative to the axis of movement.  A dip in an outside rail on a super-elevated curve is lethal in our hobby. Even a fraction of a mm can make a big difference, as I have learned harshly several times.

 

Selector, I believe you are right. The derailment on the SD45 actually happens before the No. 6 turnout, as it rides off the rails a scale approximately 30 ft. before it actually enters the turnout, making it appear that it is picking the switch. But, when I rerail the locomotive before the turnout it goes through the turnout smoothly. I think I need to shim the track at that point so that the superevelation goes completely through the turn, so that's what I'll do. Thanks!

Also, I have 2 Life Like P2K's that derail in the same place. I believe I've identified the problem. The P2K's are also six axle (SD7's)

I'll let you all know if that works.

Thaks also to Graham Line for pointing that out.

[dinwitty]

Any derailing issues you check both. as noted the 6 axle was pre-derailing before hitting the switch where it all fell out. longer stiff wheelbases do not like track irregulaities especially around curves. But I might run my BLI Y6b over your track and have no problems. Prototype trucks flex with springs. I look for truck flexibility. Your axles should also slide left/right to get around curves. When you run into these problems, run the engine slowly around the trouble area and watch the trucks. My modules have lumpy areas on the track and those lumps are good spots to find truck problems with flexing or whatever, or if cars have interfering details which I remove/grind/whatever to fix operationality. My BLI 4-4-4-4 had issues on curves and found the lead truck hitting the shell, a dremel tool carved some inner shell out and made truck room, runs great. Only took a nib of cutting. Walther's Hiawatha Cars had a lot of interference details, so my horde of Hiawatha cars got some hacking around, Walthers Bi-Level cars had issues, fixing done there then I compared them to the KAT equivelents, Kato cars ran flawless, no mods/fixing. All about design.

[rrinker]

selector

How out of gauge is "out of gauge?" 0.5 mm?  0.8mm?  1mm? None of those is likely to cause a derailment, even on a curve unless it's about 1mm too tight...or more.  If too wide in gauge, the typical HO scale wheel with its wide tread is not likely to derail.  Instead, I have found that derailments on curves, especially those super-elevated, tend to be due to uneven rail heights across from each other relative to the axis of movement.  A dip in an outside rail on a super-elevated curve is lethal in our hobby. Even a fraction of a mm can make a big difference, as I have learned harshly several times.

 

 You'd be surprised. Yes, there is a lot of 'slop' built in to the track and wheel standards, which is fine if the combined difference of the track and wheels is within that tolerance, but if the track is on the narrow side and the wheels are on the wide side, or vice-versa, it will be a problem. The NMRA gauge just measures go/no go within that tolerance band, you need to do some careful measurement with accurate calipers to get exact numbers and see how things really are. 

 I say a 'lot' of slop because I once worked in a precision machine shop where parts had to be kept to the nearest 10 thousandth of an inch - .0001", .00254mm. By those standards, .5mm is rather sloppy. The NMRA standards were designed to be fairly lenient so that the average home hobbyist could actually build things that worked without resorting to expensive precision tools - and to help keep manufactuering costs down as well. These days we could wasily mass produce things to tighter tolerances, but the cost would skyrocket. The machines needed to maintain .0001 tolerances cost a lot more to buy, maintain, and operate than ones that do .01. Not to mention differences in manufacturering techniques.

 So while you can often get away with things - if you run that way, eventually it will bite you, when you use say one turnout from a different brand that tends towards the opposite side of the allowable range. Suddenly equipment that runs perfectly fine everywhere else now derails at this one spot. The track is quick to take the blame, but it's more likely to be the wheels.

                                    --Randy

 

[E-L man tom]

rrinker

So while you can often get away with things - if you run that way, eventually it will bite you, when you use say one turnout from a different brand that tends towards the opposite side of the allowable range. Suddenly equipment that runs perfectly fine everywhere else now derails at this one spot. The track is quick to take the blame, but it's more likely to be the wheels.                                     --Randy

Point well taken Randy. I haven't looked into the wheel/truck item yet, but I believe that there is also, to some degree, trouble with the track, especially with superelevated track and at some turnouts, which I don't believe are level. I have now identified some very consistent trouble spots and will fix them when I have tested all or most of my locos, mainly the 6 axle ones as well as the ones that I will use the most on the layout. I'm taking note of each trouble loco, writing down what and where the trouble is.

To your point, I have an Athearn BB SW7/SW9 that has all kinds of issues (I bought it years ago used, at a train show and it is now painted in my freelanced road livery). The issues range from derailment on some turnouts to poor track contact, causing stalling. I don't know if I can fix these issues and I may just give up on it. I recently acquired a LL P2K SW9/1200 which will also be painted into the same livery. It has no issues at all and is a great runner. I will almost exclusively use 4 axle equipment on this layout, but with as many locomotives as I have (35-40), I'm bound to rotate some 6 axle power in from time to time.