I recently purchased some Athearn passenger cars. I am experiencing derailments on 23 inch radius curves. No matter what I do just the slightest imperfection in the track is where the derailment occurs. I would like to replace the wheels with wheels with longer flanges but I don’t know where to find the specifications or what to ask for. Could someone please get me started in the right direction. I saw something in an old Walthers catalogue about wheels with RP-25 contours. What is this and where can find the specifications for wheels?
Please help me!!
Larger flanges will only cause additional problems elsewhere. Replacing the wheelsets w/ metal 36" or even switching out the trucks is whats needed. Before doing this, check that the truck/ bolster screw is loose enough to allow some slight side to side movement. Adding additional weight should also be done. This should solve the derailments.
Bob K.
It sounds like the trucks are tightened all the way down. The Athearn flanges are more than deep enough. RP25 flanges are more shallow than what you have. In this case, especially with 23" radii, those wheels and talgo trucks should be more than sufficient. As stated above, the trucks need some play in them.
RP-25 wheel are what you already have. If they are plastic you can replace them with metal, but your problems are elsewhere.
Your trackwork probably has more than “slight inperfections”. Put your head down and ‘eyeball’ it. Trucks that are ‘too tight’ also need to be loosened to follow the tracks.
Can you explain what you have done. Check wheel gauge, check the trucks to be certain they turn easily, one of them is loose enough to allow some side to side rocking, couplers not dragging, etc.
I can’t imagine that the flange depth has anything to do with the derailing problem.
This is an NMRA specification. Athearn wheels are generally RP-25.
Truck geometry is like a three legged stool. Adjust the bolster screws so that one truck is a little snug to keep the car from rocking too much and allow the other truck to rock freely to allow for irregularities in the track and everything should be OK.
Look for obstructions when the trucks are on curves. Sometimes they interfere with the coupler draft gear or steps. You might need to carve some of the underframe with an Exacto knife to allow for clearance.
ED
As someone said earlier tRP-25 is probably what you already have. Just for your information the RP25 is a Recommended Practice of the National Model Railroad Association. They have a web site. The flange is .025" deep to the tread, hence the 25 in RP-25. There are also other specifications to this RP, such as tread width, flange width…etc.
What keeps the trains on the track is not the flanges so much as the shape of the flange and the fillet that transitions from the flat tread of the wheel to the flange. A deeper flanged model truck is usually much more “square” between the tread and flange and they are more likely to derail. Deeper flanges are usually used on models intended for the european market(they have their own NEM standard), and their switches and “crossovers” (crossings) are built to reflect the shape of the wheel.
Hope I made no mistakes in this simplified explination, but if I did I am sure someone will set me straight.
Paul
Dayton and Mad River RR
Hi there,
I ran Athearn cars regularly around tighter than 18" curves… the streamline ones anyway, the Pullmans are a slightly different proposition. Make sure the bolsters are loose to provide flexibility but double check the track gauge where they derail; curves in particular tend to tighten gauge as well. You can use spikes even through flex track sleepers as I do ( some of my flex track is probably 40 years old) to correct gauge. You can contact me off list if need be xdford47@yahoo.com.au
Good Luck
Trevor
Ugh, too many gremlins to drive us crazy!! I would look to your current wheels first, getting an NMRA wheel guage. Too narrow will cause problems with guard rails in switches and cross overs. The gauge being too wide will force the wheel flang to climb the rail and off onto the ties.
Second visually inspect the centering of the wheels on the axles, which can cause the truck to track off center if all wheel sets are off center, or cause the truck to track crooked, with a “Dogie gait”. Either of these conditions can cause the wheels to be “pulled against the offending rail” resulting in derailment.
Third, with the trucks back on the car, check clearances and their ability to swivel without contacting body parts, or binding through their intended travel. There are times when a piece of brake rigging or shoes will contact a step assembly steering the truck to the ties instead of following the rails.
Last retry the car on the layout and mark any places that still result in derailments, even occasional ones. Inspection of the rails may reveal some unrealized narrow guage problems or a slight mismatch of the rail ends that the flanges “pick” sending them to the ground.
And finally welcome to the hobby and the forum. Best of luck with exorcizing the gremlins.
Will
I’d keep an eye out for problems where the cars are derailing. Is it just that spot, or are there others? If it’s just one place, there might be something wrong with the track. Maybe the rails are kinked, maybe the rail is atop the joiner–instead of in it, etc. Take a close look at your track. If all is well, then it might be something with the car. Try pushing a car through the area, and watch the wheels closely.
I had a problem like this bug me. For months, I couldn’t figure it out. I put temporary weights in the cars, made sure the Kadee trip pins were bent up a bit, and installed some metal wheels…all to no avail. Eventually, I traced the problem to the diaphragms. Whenever the cars would go around a curve, a corner on one diaphragm would get caught on its mate…and force the cars off the track. If it wasn’t that, it was that the diaphragms were mounted a hair too low. They’d catch the coupler, and cause the same problems. Removing the diaphragms worked, at least temporarily.
All NMRA Standards (S) and Recommended Practices (RP) are available on the web.
http://www.nmra.org/standards/consist.html#rps
Click on the entry for RP-25 for a reference and a copy of this RP.
But as Will pointed out above, I’d start with the NMRA standards gauge checking the wheels and tracks causing the problems.
http://www.nmra.org/standards/rp2.html
Hi, Welcome.
Also try turning cars around, putting them in different order; looking for same cars derailing in a different place or all cars dereailing in the same spot and running the whole train in opposit direction to see if that changes anyting . See if any changes change how a car reacts or if the problem changes is some way. I believe if you do everything everyone has suggested, you will become the detrail expert and we can all ask you questions.
All kidding aside, I hope you find it, let us know what it was and how you found the problem and whose advice helped the most.
I have to agree with about 99% of the replies above but I think the real problem is that track imperfection mentioned. I’ll bet that the trucks are 3 axle trucks an those passenger cars and if so any track imperfection is going to cause problems. First off the wheel flanges do have a lot to do with keeping wheels on the rails, however, because our model trucks are ridged and the bolster is not in the center of rhe truck, any dip or rise in the rail will cause the wheels further from the bolster to rise above and over the rail. True, the wheel contour tries to keep the wheels “center” on the rails, but even rail railroads have a problem with this on some curves so they install flange greasers to keep rail and wheel flange wear to a minimum. Ken