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How To Stop Bogies Derailing on a Turnout
Julian asks readers:
“I have a seemingly intractable problem. The front bogies on my new OO Hornby West Country jump off on the turnout when having to turn. The first of the outside bogies seems to fall out through the gap in the outside curve where the crossing is and before the check rail on the inside has a chance to hold the flange of the inside front bogey. I have tried widening the bogies but what little extra there is before the wheels come off does not help. I have put a piece of foam under the bogies and while that damps the jumping it does not cure it. Help please!”
5 Responses to How To Stop Bogies Derailing on a Turnout
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Julian, I am going to suppose that you have very sharp switches (maybe number 4’s) The switch rails have to stay in gauge all the way through the switch. If the rail gets too far away from the stock rail or too close it will squeeze the wheels off the track. Some switches have big gaps near the frog and the wheel misses the rail and after the frog. Check your gauge first. If you have the tight turning switches then I would also look at replacing them with a shallower switch such as a No 6 switch. a number 6 is where measured at the frog of one unit of measure such as a cenemeter So you will have 6 units from the tip of the frog out 6 measurements Then at that point the nfrog rails should have spread to 1 of the same unit. So 6 units from the point of the frog and at that point there should be only one unit of spread of the rails (measure to theinside of the rails where your wheel flange runs.
You should also have your guide rails travel from before the frog to after the frog. When I build my homemade switches the guide rail also needs to make sure the guide rails and the stock rail needs to have the clearance for a truck and all of it’s wheels be able to flex through the whole guide rail;. A friend of mine that taught me how to hand lay my rails said that the wheels should track through the whole switch without the guide rails being there. If you do that then the guide rails will protect a set of wheels from derailing if they are a set that are not in gauge correctly.
from Newman Atkinson
I had the same problem, different make of loco. I found if there is a traction tire on a leading wheel of a 2 axle bogie it jumped. Turning the engine around and running it so the traction tires are in the trailing bogie fixed it. Of course you have to adjust the CV29 so all driving is normal again. Hope it helps
You say that the leading wheel of your new loco falls through the gap in the outside curved rail which indicates to me that the wheel is going the wrong side of the turnout crossing’s pointed Vee nose. You widened the Back-to-Back distance between the wheels which probably made things worse. I suggest that you reduce the Back-to-Back distance to a little less than it was originally. This will allow the check rail to do the job it is there to do.
Some point (switch) blades are quite flimsy and can get out of gauge. Gentle bending of the blade inwards could fix your problem.
I had a problem where wheel flanges were too tall for the frog. I cut the frogs deeper with a Dremel. Then I filed the few wheels that continued to fail.