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Switches and Frogs
Alan asks readers:
“I am having frustrating times with my trains derailing – both locomotives and cars. It is the frogs in the switch that is causing the derailments. I have checked and double checked the switch tension to no avail. Can someone guide me to a solution please?”
14 Responses to Switches and Frogs
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Derailing at points is not an easy diagnosis.
Firstly take note of which loco/wagon is derailing. There might be a few, or only a couple.
The problems here might be wheel gauge and back to back. Both are critical. Get an NRMA or other gauge, don’t rely on your eye or callipers. If they are out make adjustments by moving the wheels on the axles – a bit hard if they are one piece castings (plastic). If plastic replace them. You wont have to change over all the wheels on your layout, just the problematical ones. Next check for wheel wobble and concentric-ness (is that a word, I hope so), again if these are an issue, change them over to some that are true.
Only now do I blame the track!
Check the groove between the running rails and the guard rails – use your newly acquired NRMA gauge. Check for loose ballast or other obstructions in these grooves. This process will also alert you to gauge issues – run your gauge right through the point from closure rails to, and through, the frog, adjusting to correctness as you go.
Check for gunge and loose ballast between the running rails and the points themselves – they might not be closing fully and the wheels might be “picking” the point, running up and over it causing a derailment. Make sure that the system holding the point to the running rail has sufficient tension to do the job.
Finally sight down the running rails and ensure the “line” through the frog is straight and true. If not adjust it.
All adjustments rely on the type or brand of point – whether commercial or home made and you might need to talk to the manufacturer.
I hope that helps
First I would start with the switch if you have a national model railroad association rail gauge. Such as this picture. If you are modeling in ho Scale. You can pick one of these up at your local hobby shop. Second I would check all the wheel width on your locomotives and rolling stock. Also check your switch points make sure they are not sharp pointed. If they are the need to be filed down just a little. I hope this helps a little.
Paul W.
Hi Alan. Obviously there is something wrong with the alignment of the frogs or guide tracks can you tell if the flanges of the wheels are to big for the type of track i.e. the depth of the frog may be lifting the wheels and causing your problem or the frog itself the wheels are hitting the edge of the frog as they enter. you do not say what type or if they are second hand or new. Check the track gauge to make sure that it is not to tight.
Hi Alan. What brand and scale are the turnouts?
Bachmann and Atlas. Same problem with both.
I don’t see what scale you are using mentioned here. I have N scale but I think this applies to HO as well. The first thing I would check is are these older locos and cars? We call the older wheel sets cookie cutter (or pizza cutter) wheels. The flange is large and out of scale. This causes them to ride high when crossing a frog and in my experience causes most derailments for me. Get some new wheels with more prototypical flanges and most problems will go away at switches. Locos would be harder to replace wheel sets so new locos might be better. Old vs new flanges are easy to tell the difference if compared side by side.
G’day Alan.
One trick I learnt the hard way, is to make sure you have a straight section of track (only need be 2-3inches) into and out of the points. Never go from one direction bend directly into another.
I do agree with the others, guage everthing – track and rolling stock.
Like the other respondents say check the back to back measurements of your wheels but I find the usual 14.5 mm in OO / HO is too wide and I use 14.2mm, not much of a difference I know but just enough. I dont have straight rails added to my points, on the contrary I saw bits off points to fit them into smaller spaces,
I have found similar problem and isolated it to the rail gauge (55 with 80) this does not work unless there is lead into the gauge heights difference also if there is a short straight prior to the switches this does help to alleviate the derailments…
Check the switch rail is tight (and stays tight) against the side rail in each switch direction before and after the loco passes.
If there is looseness or a slight gap, the car wheels may slip into the gap and derail.
Hi Alan, almost have been said about this problema. Meanwhile verify also if for any reason the turnout is out of gauge. You have told that almost your running wagons and locos derailled in the frog. See carefully what´s happening when a loco or a wagon passes throu frog. Reduces almost you can all your speed and see with attention what´s the behaviour and then try to correct it. As Paul says use a standard gauge, and also see the flanges of all your running cars and locos. I don´t know if this helps or not, but´s waht I can say at this moment. I have had a lot of problems when I begun 40 years ago, but now I build myself the turnouts.
Álvaro
Alan,
Every one that has commented on this so fat is absolutely right. But there are other things to consider too. Your wheel set on your cars, Plastic or metal wheels? are the couplers mounted to the wheel trucks? Is this backing up or running forward through the switch? Generally these things will happen on sharp No. 4 switches and not because the switch is so sharp but also the cars are not capable to handle them without some fixing up or modifications. Even the Kadee Couplers will interfere with the best of the switches if the if the metal coupling wire hangs too low.
As far as the switches themselves, Snap motors like the ones that come on Atlas switches will shift around and you have to take your finger and ensure the switch rail has swung fully into position. I have 2 left on my layout that are due to be replaced with better throws soon but they stay in position when they are pushed to their full position right now.
I am now making my own switches for my main level. I currently have 31 on my staging level (most are atlas) with various throws on them. After the main level is completed I will go back and work the switch motors and throws on them with a few main switches to be replaced with the home made ones. I am currently working on my 4th, 5th and 6th switches and I feel they are better than any store bought so far. But they take time. They are all hand laid. A standard #6 switch from Atlas costs in a range of 17 to 25 dollars not counting a throw. My homemade switch so far the average cost to make is under 9.00 in material. They are worth the time to do. You should watch others build some first as I did. There are companies that have jigs and pre-made stuff for them and you can have 200 bucks wrapped into it before you even get the first one done.
I am totally scratch making mine using various gauges and a filing block. and so far so good. My latest is a triple switch all in one that cuts the space needed for 3 down to 2. But back to the standard switches…. I am backing 40 car trains into a yard with full success and most are Atlas switches.
Look at the cars and the couplers used, Old standard horn couplers are only good to back a few cars through switches at a time. If they are mounted on the wheel trucks it is worse. Even if the horn couplers are body mounted many did not travel well left to right and were spring loaded in one direction, and may not allow enough movement to negotiate Plastic wheels is usually not the main issue but if the wobble in the truck bearing it can be.
Check the gauge of the switch rails to see if they are holding gauge throughout the distance from the other stock rail not just the ends. I had a homemade one I got at a show that held gauge at each end of the through rail but through the rail it had to be re-bent. and top hold it I had to tie it to the other switch rail to hold the correct curve which means some work and a way of insulating the rails from each other it needed. Also as I have found the straight switch rail will generally work ok into the frog but the curved rail sometimes won’t. Even the curved switch rail needs to be straight entering the frog. (a manufactured switch may not be able to adjust) but a manufactured one is usually other issues..
Gauge of wheels, and track have to be right, the rail through the frog has to have the proper clearance from the guide rail beside it the wheel to pass there also needs some clearance of the area under the wheel that helps hold the wheel up during the transition to the frog itself. Check these. If a switch is working right when I build one the guide rails on the outer track should not be needed if the clearance and travel of the wheel tracks right along the rail transitioning to the frog.
I am backing 20 cars of the long 86 foot box and auto racks through my switches and no derailments. and that is store bought Atlas switches. from Newman Atkinson
In addition to all that has been said so far, when checking the points with the track gauge have a look at the check rails to ensure they are holding the wheels to the stock rail. This will prevent the wheel picking up the frog. If the gap between the stock rail and the check rail is too large it can be be shimmed with thin plastruct or similar.
Hope you get the problem fixed soon.
Alan,
I just thought of something that Peter mentioned, While hand making my own switches a friend of mine told me that if the frog rail is properly aligned with the approaching switch rail, it should handle the wheel trucks without having the guide rails installed.without any trouble. So as I build the switch I make sure the car will follow the rail without the guide rail installed. You also need the guide rail spaced properly from the stock rail as previous stated. I am not saying to build it without the guide rail, just that if it is right it should not really need it. But we always do install them.
Newman