KATO F40PH derailing on diverging PECO Med Turnout

[OldEastRR]

Loco runs fine over all the ME #6s I have but at the only part of the mainline with a PECO Medium switch the trailing truck derails on the diverging route. Checked clearances and spacing on rails, points, wheel gauging but can't find anything wrong. Anybody else have this problem?
Running down the straight leg of PECO turnouts doesn't bother it. 

[Hansel]

I had a similar problem with a Kato switcher.  Evidently the two halves of the frame were only held together by the plastic fuel tank unlike most other frames where they are held together by screws and nuts at the two ends.  I have Peco C55 track.  After about a week a running the new loco it would derail on my turnouts.  The truck had too much play in its movement and was dropping into the space at the frog.  Since the two frame halves were only held together by the plastic fuel tank, the frames were not holding the trucks tight enough so that the trucks would fall into the frog rather than "holding" the trucks tight enough so that the trucks would be held somewhat horizontal and not completely fall into the gap between the frog.  As in any root cause investigation you should show that you can "turn on" and "turn off" what you believe to be the cause.  I "turned off" the cause by temporarily clamping the two frames together and the trucks did not fall into the frog.  I sent back the new loco for a refund to the retailer.

Not sure if your problem is the same.

[alhoop]

I had  derailment problem on the diverging route of a PECO  medium LH
electrofrog turnout. I had tried metal replacement wheelsets from different
manufacturers and one set had a tread that was narrow enough to allow
the wheel to drop down between the rails and derail. Unfortunately I didn't
keep records of which manufacturer it was but a different set of wheels
cured the problem.
Al

[jdcolombo]

Loco runs fine over all the ME #6s I have but at the only part of the mainline with a PECO Medium switch the trailing truck derails on the diverging route. Checked clearances and spacing on rails, points, wheel gauging but can't find anything wrong. Anybody else have this problem?
Running down the straight leg of PECO turnouts doesn't bother it.

When you say you "checked clearances" did you check the spacing between the guardrail and the frog using the NMRA gauge?

Some Peco switches have guardrails that are about .010 too close to the frog (or put another way, the clearance between the stock rail and the "guardrail" - quotes because it is actually plastic - is .010 too wide).  This allows properly-gauged wheels to slide too far over and pick the point of the frog.

The solution is simple.  Take a strip of .010 x .060 styrene, cut it to the same length as the "guardrail" and glue it to the guardrail with a couple of drops of plastic cement.  Use two round toothpick ends wedged between the stock rail and the shim to hold it in place against the angled part of the guardrail until the glue dries.  Paint brown.  Finished.  If you have some .010 x .060 styrene strip, this fix takes about five minutes.

John C.

[craigolio1]

I did this on a friends HO Peco turn out and it worked like a charm.

Another thing to look for, and I think it was touched in before, is that with newer models having finer flanged wheel sets, and turn outs still having 1980’s huge spaces in the flangways on the frogs, the wheels can sometimes drop down into the space and then on the way out pick the point on the frog and derail. It happens in the straight and diverging directions but derailment is more common on the diverging route.

The solution can be to shim the bottom of the flange way so the wheel can’t drop. This works best when all of the flanges in your fleet are the same size. If you still have some white giant flanged then they will of course ride up and over the shim.

Craig

[OldEastRR]

Already had installed both types of shims. But the idea one axle dips down then picks the point may be what happens -- the truck seems to drop slightly when it hits the frog. But why only this loco when other KATO, LL, Atlas, Atlas-Kato, Bachmann, Athearn Big Boy, and BLI locos (and zero rolling stock) have no problem --huh???? And the Bachmann is a 44T!

[craigolio1]

Check the depth of the flanges. It’s possible you other models have deeper flanges than the F40 so they don’t drop as much, or at all.