Dapol Hall turns right at Peco long crossing!

[abenn]

On my N-gauge layout I have a Peco long crossing which is approached on one side by a right-hand curved section of track, approximately 14" radius with a short transition. My trackwork is all Peco code 55 electrofrog, and all my modern day locos, and my Dapol 0-6-0 tank, negotiate it with no problem.

But my Dapol Hall loco's bogie's leading left-hand wheel flange snags the far-side rail and is deflected to the right, and the whole loco follows it until it trips the power supply when it touches the running rail at the far side of the insulated rail joiner. It seems that the bogie is biased slightly to the right because it hasn't had time to straighten up after the curve, so I'm wondering if a bit of added weight might solve the problem.

Has anyone else encountered this or a similar problem with the Hall, or any similar N-gauge loco?

[Admin4]

i have had something similar in 00, it was caused by the back-to-back of the bogie being out. i got myself something similar to this to fix it. The tool is fantastic and is so useful i would suggest grabbing one anyway.

[End2end]

I'd say the same as Alex. Get yourself a back to back gauge. It's a railway modellers essential tool. I have a DCC Concepts one which I've used even on Hornby wheelsets that often come new out of the packet, out of gauge. It's solved many a derailing problem for me on both new and second hand rolling stock.
Thanks
End2end

[abenn]

Yes, after posting it struck me that it could also be a back-to-back issue. I had a gauge when I was running 00, and found that many of my models needed adjusting.

I'll get an N-gauge version before I try anything else. Thank you.

[Bigmet]

And if the wheelset is perfect to gauge then what?

What happens if you run the loco forward through the junction in the other direction? And backwards through the junction in both directions?

Can you take the bogie off and run it through the trouble spot on its own?

Worth trying all these things, to see if it is direction dependent, and whether it needs the rest of the loco present to make the bogie come off the track at the derailment location.

Probably the commonest derailment cause coming from a bogie mounting is that the bogie is not free move sideways and rise and fall on the track but is being either lifted by the loco or trapped in some way. (Sometimes when the bogie is being trapped one of the wheels will stop turning just as the trouble spot is approached, that's a real giveaway that loco structure is bearing on a bogie wheel somewhere.)

[b308]

Probably the commonest derailment cause coming from a bogie mounting is that the bogie is not free move sideways and rise and fall on the track but is being either lifted by the loco or trapped in some way. (Sometimes when the bogie is being trapped one of the wheels will stop turning just as the trouble spot is approached, that's a real giveaway that loco structure is bearing on a bogie wheel somewhere.)

It could be either, Bigmet.

I'd agree to try the bogie "play" first, though... Does it go through all the other points and crossing OK? If it does then I'd have another look at the point concerned, looking for ballast in the crossing causing the bogie to ride up or undulations in the way it's laid.

If you have a micrometer then you could quickly check the B2B without buying a gauge.

[abenn]

Thanks guys. I've got a gauge on order at the moment so I can check the back-to-back.

The loco in question runs through standard turnouts okay, in either direction, and over this particular crossing on the other road, which has straight approaches either side. What I did do before my original post was observe it very closely at crawling speed, with a torch beam on it, to observe what exactly was happening. All the wheels were still turning at the point where the leading wheel got kicked in the wrong direction, and the crossing is completely clean of all ballast and other dirt.

I'll do some more tests tomorrow, as you suggest, pending arrival of my gauge.

[abenn]

Sorted!

Thank you guys, you're spot-on. My DCC Concepts back-to-back gauge arrived today and it was a bit of a tight fit between the bogie wheels. I removed the bogie and then the wheels, and eased the wheels into the gauge completely, thus spreading them ever so slightly. When I put everything back together the loco ran through the crossing without turning right.

To be honest, it might not have been the back-to-back dimension that caused the problem, for it's only changed by a fraction of a gnat's whisker. So maybe the removal and replacement of the bogie eased some restraint at the connection -- certainly the bogie was very free to swivel, but I think its side-to-side movement was a bit stiff before I took it apart.

[Admin4]

either way is good to hear you have sorted the issue

& the back to back tool will come in handy now you have it so a win win

[abenn]

... & the back to back tool will come in handy now you have it so a win win

I said in my OP that all my other locos negotiated the crossing okay, but I'd forgotten about a Farish class 66 that I'd never run on that route. When I tried it, it snagged! So yesterday my back-to-back gauge was busy sorting out all six axles of that loco, which were even narrower than my Hall had been

[railsquid]

... & the back to back tool will come in handy now you have it so a win win

I said in my OP that all my other locos negotiated the crossing okay, but I'd forgotten about a Farish class 66 that I'd never run on that route. When I tried it, it snagged! So yesterday my back-to-back gauge was busy sorting out all six axles of that loco, which were even narrower than my Hall had been

Did it work better?

[abenn]

Yes thanks railsquid. The class 66 runs fine over the crossing now.

[Bramshot]

I bought a DCC Concepts back to back gauge in n scale when installing contact springs while lighting coaches. I found that all my stock back to back is set closer than the gauge, which makes me wonder about the gauge dimensions. Have everyone but DCC Concepts got it wrong?

[abenn]

I did a quick check on some other of my locos, and they're okay according to the DCC Concepts gauge. The main thing is, the ones that had a problem on my crossing were both narrower than the gauge and, when set by the gauge, they crossed it without problem. So at the moment my money is on DCC Concepts being right.

[railsquid]

Yes thanks railsquid. The class 66 runs fine over the crossing now.

Thanks, this thread finally inspired me to acquire a gauge, as I have a couple of locos which disagree with some points in some directions.