6 axles & 18/22 inch radius curves

[Anonymous]

I have a couple of 6 axle diesels some can handle 18 & 22 curves ( I would like larger curves but space is an issue) and other by the same manufacturer derail. How can I ensure that 6 axle road units don't derail?

A second question. I replaced Athearn 42 wheel sets with NSWL wheel sets in one unit and as the trucks roll down the rail it feels like the wheels are bouncing up and down. When I look at them on the diesel they also seem to have too much play from side to side. How would I fix this? Thanks for any help or suggestions.[:I]

[Don Gibson]

QUOTE: Originally posted by mclare

I have a couple of 6 axle diesels some can handle 18 & 22 curves ( I would like larger curves but space is an issue) and other by the same manufacturer derail. How can I ensure that 6 axle road units don't derail?

22" RADIUS seem's to be the dividing line. Some do some don't. Insurance?
You want assurance?? Run 4 axle diesels on the 18"r portion. That's what real railroad's do - or relay their track with wider curves. (Work's for them).

QUOTE: A second question. I replaced Athearn 42 wheel sets with NSWL wheel sets in one unit and as the trucks roll down the rail it feels like the wheels are bouncing up and down. When I look at them on the diesel they also seem to have too much play from side to side. .[:I]

The SIDEPLAY is how they get your engine to take 18" curves. 'Lateral' play does not translate into 'vertical' play. I suspect something else is at play. Wheel alignment (wobble)? Bumpy track? Loose fit?

QUOTE: How would I fix this? Thanks for any help or suggestions.

I'd start with an NMRA guage on your wheels.

[Anonymous]

Most all manufacturers say that 6 axle units need at LEAST 22" curves to run correctly. There are very few 6 axle units out there that can work on an 18". My curves are all 22" and I have no problem with my big 6 axle units on them. If you have a unit that derails on 22", then you may need even bigger curves (maybe 26" or bigger) if you want to use that unit.

[selector]

Flange height may be a factor in your hopping axles, or if they are to standard, perhaps something is causing them to bump up..flangeways that are not deep enough in turnouts, ballasting material too high where the flanges run, gaps too large in turnouts and crossings, or even binding inside the journals.

Seeting your wheels inside gauge by about 10-15 thousandths of an inch on those six-axle trucks may buy you smoother running around 18" curves, but getting them there will be a chore, and may cause other systemic problems that are not currently there.

[grandeman]

Most 6 axles units have a longer wheelbase than compareable 4 axle units (obviously). I'd stick to the shortest 6 axles locos for best running on tight track. Better yet, go to 4 axle units and be done with it.

[bobwrght]

I have several 6 axel units running on 18in radius with only one problem. The Athearn SD40-2 use to derail and slow down some in the curve. My Proto, Bachmann, and BLI loco's run just fine. I think the Athearn is shy in weight and the axels are loose with lots of slop.
If they tend to derail in the same area of track , check the track gauge, level of track and for any side to side dips in the rail. You may have to shim up one side.
I wish i had room for wider curves.

Bob

[Anonymous]

Check for possible obstructions to the trucks swiveling sufficiently to take the radius. Is there a step that the truck hangs up on, enough clearance between the gear tower and the frame, or could the truck be fouling the coupler pocket? Some 6 axle units simply will not track on tighter radius, 4 axles may be your only choice.
Will

[BRVRR]

I have Athearn BB SD40-2s, an FP-45 and Alco PAs running on 18' radius track and snap-switches without major problems. Yes, they look a little funny, but room is at a premium. They do run and look better on the 22.5-in. mainline, but they run.
The slowing in the curves is probably binding. Make sure the wheels are in gage and the the trucks swing freely. Sometimes a break cylinder or ladder may interfere. I had a piece of flex-track out of gage once too.
The 'hopping" may be due to any of the suggestions above, or to a bad wheel-set. I had a couple of new LL wheel-sets where the axles were off- center.
If you are using snap-track, ensure that it is laid properly. Sometimes the radius is actually smaller than the intended 18".
Good luck! I'm sure the problem can be solved.

[trainboyH16-44]

My suggestion, atlas makes C-424s and P2K makes GP38s[:D]
Trainboy

[bbrant]

QUOTE: Originally posted by mclare

I have a couple of 6 axle diesels some can handle 18 & 22 curves ( I would like larger curves but space is an issue) and other by the same manufacturer derail. How can I ensure that 6 axle road units don't derail?

What I've found is to make sure the track is layed perferctly for reliable operation on any radius. I, too, have limited space - my layout is a 4x8 with a 2x8 extension for switching.

The 4x8 has min. 18" radius curves. Even though I run 4 axel units on them (for the most part) I made sure when laying the track that it was good enough so 6 axel units could take the curves without derailing. So far, so good.

Good luck to you.

Brian

[ac4400fan]

Is The derailment happening when its going around a curve? if this is the case i had a simaler problem ,it might be that the outside rail on the curve is lower then the inside rail .this can cause a problem especialy with 6 wheel axle trucks,,put somthing at that point of derailment under the outside track to elevate the outside rail ..see if that helps ...

Good Luck!

Carl..

[nedthomas]

Do the units derail when running alone or with cars coupled? The draft gear may be limiting coupler swing but I would expect the cars to detrail and not the engine due to the greater weight. Real diesels have smaller turnning radius when running light due to draft gear limits.

[willy6]

Last year on this forum I reported a 6 axle locomotive problem derailing especially on #4 turnouts. And a forum member,( i think it was Don Gibson) told me what to check for. I used all atlas track and turnouts. Come to find out, my problem had a simple solution. I got an NMRA gauge. It was the wheels on the locomotives They were not in alignment. Have not had problems since.

[Dr. John]

Transition curves can help. Derailments often occur at sudden angle changes in the track. Simply offset the straightaway section by about one half inch from the curved portion then curve the straightaway gradually to meet the fixed radius. This works best with flex track or handlaid, obviously. With sectional track, you can get a similar transition using 22" curves leading into 18" curves, assuming you need such a tight radius. Be very sure that rail joints are smooth - some work with a needle file can handle that.

Generally, six axle units have more difficulties with sharp turnouts (Atlas Snap-switches) and some No. 4s. If possible, use No. 6 or greater turnouts.

[Anonymous]

I run SD50s, SD60s and SD70s on 22" curves without problems. I also have an Athearn BB FP45 that can take 18"s. I still usually stick to 4 axle power on the 18"s though.

[palallin]

Find or create replacement axles for the center of each truck that use blind (flangeless) wheels. Behind the truck sideframes, you will not see that the flanges are missing.