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Post by fabforrest on Oct 15, 2019 0:21:10 GMT
My brass hybrid Mikado (beautifully lettered and weathered by Harry Heike) has started to derail, seemingly on switches. It does not happen every time, but about every 3rd or 4th time though. It is always going through the turnout. On the crossover pictured below, the train is traveling right to left and takes the left into the turnout. The derail would result in the drivers (!) leaving the tracks.  It took some doing, but i was able to get video. I accidentally show in slow motion, but I think that is good. You can see that the wheel on the rear truck lifts up, jams and eventually forces the drivers off. I have lubed the post that the truck and tether pivot on. No joy. when I first look at this video, i thought the wheel was riding up on a rail, but I do not think that is the case. It continues to rise above the rail. It happens on other places, so i don't think it is the switch itself. any ideas??? vimeo.com/366372211 |
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Post by fabforrest on Oct 15, 2019 0:30:17 GMT
could not get the video to show up in the thread.
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Post by sdivtim on Oct 15, 2019 1:27:54 GMT
Have you checked the guide rails on that switch to see if it is scale? Can you run another loco with a single axle trailing truck to see? Is the screw loose on the piece that holds it in place?
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Post by Pennsy484 on Oct 15, 2019 5:48:08 GMT
Watched it like 20 times. Idk. Even with the slow mo it's hard to see without being there. But the way the side of the truck nearest the camera behaves makes me think maybe the problem is on the other side, like the wheel is falling in. Or it could be just a combination (close side goes up, ither side fall in causing closer side up even higher. But to lift the rear drivers like that, it seems like the far side is falling in and then getting jammed on something.
I've been through similar stuff many times. I watched it over and over again and eventually found a fix. I hope you are able to do the same.
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Post by josef on Oct 15, 2019 9:26:58 GMT
My thoughts are as Pennsy484 and from seeing same.
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Post by fabforrest on Oct 15, 2019 11:49:42 GMT
“then getting jammed on something.”
I have stopped the engine when the wheel starts to lift and jammed is the right word. Difficult to move.
what is the scale width for the track?
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Post by josef on Oct 15, 2019 12:07:58 GMT
“then getting jammed on something.” I have stopped the engine when the wheel starts to lift and jammed is the right word. Difficult to move. what is the scale width for the track? For me, a K-Line Berkshire that started doing that, it was that somehow the trailing wheel got out of gauge. Taking wheel out and free running on track I saw this and pulling wheels back solved the problem. If its only on one turnout that this happens on, I read were someone had this problem at one turnout only and was suggested that maybe the turnout was fastened to hard down squeezing the rails slightly together and causing especially engine wheels to ride atop. |
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Post by Deleted on Oct 15, 2019 13:01:24 GMT
I would guess the trailing or leading truck is getting stuck and won't swivel correctly
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Post by laz57 on Oct 15, 2019 14:33:20 GMT
Hi FORREST,
This happened to me once with my MTH Reading T1. Drove me nuts. Until I checked the underside of the tender, there was a screw that had loosened up and impeded the movement of the drawbar. So check foe loose screws or if it has the new draw bar system the springs might be not getting the right stretch. Let us know what you found.
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Post by Pennsy484 on Oct 15, 2019 15:00:20 GMT
Hi FORREST,
This happened to me once with my MTH Reading T1. Drove me nuts. Until I checked the underside of the tender, there was a screw that had loosened up and impeded the movement of the drawbar. So check foe loose screws or if it has the new draw bar system the springs might be not getting the right stretch. Let us know what you found. That's a good point. I was looking at the truck wheels, but there could be some interaction between the tender and the locomotive that is pushing the back of the locomotive off the rails. S curves test the boundaries of the tether. What curves do you have there and what is the locomotive rated for. Is is a stock drawbar or a shorter one? That could cause an issue if the draw bar is too short for the curve tightness of the S curve. |
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Post by fabforrest on Oct 15, 2019 16:01:42 GMT
O54 switches. Within loco specs. Stock drawbar.
I ran the engine through without the tender a couple of times (always surprised this works) and it did not derail. Made me suspect the drawbar, but I could find nothing. Sample size may have been too small.
What should wheel gauge be?
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Post by laz57 on Oct 15, 2019 17:21:36 GMT
Hi FORREST,
Another thing to look at is take a measurement of the real truck wheels they might be a smaller width then the front or drivers and that could cause those wheels to ride up on the switch. Also check the switch itself for the width where those wheels are coming up. Hope you find it.
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Post by Deleted on Oct 15, 2019 17:59:10 GMT
Forrest, you may have a classic case of coupler bind. What is happening is that the swinging motion is hung up somehow. Make sure both move freely, and that the crab claw has enough slack in it when coupled. You can file the coupler (the movable latching part) if it is too tight. From the top, it should be two loose "commas" connected.
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Post by fabforrest on Oct 15, 2019 18:39:22 GMT
I think you were close, Volphin. The rear truck and tether share a pivot point. About halfway from that to the rear of the engine is another sprung post assembly that traverses a curved slot in the bottom of the engine. This is binding and it appears to be binding inside the engine. It grinds and occasionally catches hard. That is when the derail happens I suspect. I lubed it some more and worked it by hand in hopes of breaking through whatever it is. Was not successful. Getting at it is more than I am capable of. Gotta find someone to tackle this for me.
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Post by Deleted on Oct 15, 2019 19:53:18 GMT
The slot may need a slight bevel to operate more smoothly because sometimes the casting has rough spots.
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