Crandell, I was re-reading your post, and I agree that sometimes the slightest flaw is trackwork can be inconsequential until all of a sudden a car or loco shows up that has no tolerance for the slightest track error.
And, yes, I too have ripped up supposedly good track work to fix that slight error in order to get that one problematic car or loco running without derailment. Sort of like the shepard who momentarily abandons his flock to find that one missing sheep.
The problem with my current issue though is that the derailments have not been occurring on a single stretch of track. The derailments are more widespread occurring on several stretches of track. And, even if the fault was with the track and I rip it all up to find and fix the flaw, what happens the next time around when a new car or loco experiences derailments?
Now that I have pretty much isolated the offending truck, if derailments persist, I will just have to replace the truck.
My new Rapido CPR Budd mid dome car derailed repeatedly when coupled to a Proto 2000 GP38-2. Turned out the coupler travel on these locomotives is very limited by the slot in the pilot. The locomotive simply hauled the front of the car off the track at the same spot each time. Hauled by a Proto 2000 S3 the car tracked fine through the same spot.
One other thought about the effect of swapping trucks is to take a close look at the truck mounting boss and the riding surfaces. It is just possible a particular truck is a tighter fit on one underframe than on another (or conceivably too loose?) and performs inconsistently.
Derailments that appear to occur randomly have a bit of a voodoo aspect which can be frustrating to identify let alone correct. Track induced derailments tend to be more consistent than rolling stock issues. Even for track induced derailments it can be very difficult to diagnose and correct unless multiple rolling stock derail fairly consistently at the same spot. Often you relay the track or file down a frog and the problem magically solves itself leaving you uncertain what the problem actually was.
One example we had was a grade transition too close to a turnout. Only long wheelbase equipment derailed occasionally at that spot. Finally we had a short wheelbase steam locomotive trip over its pilot at that spot revealing the very slight error we had made. I now insist on turnouts being installed in a long enough section of the same grade in all connecting tracks to avoid this issue, preferably flat grade. Peco turnouts are most prone to this issue due to the short approach and departure track ends.
The more posts about solving derailments the better.
Rich, I had the same dread in mind when I fiddled with each section of track that seemed not to want to play nice with whatever it was that was derailing. Fortunately, that reality never occured, not once. It seemed, thank the fates, that whatever I was doing was always an improvement, if just a smidge. I never seemed to undo something that had been working right.
I think you have figured it ou; the truck must be the problem, maybe also a bit of stringlining tension or something that is making the last couple of cars want to get jerked out of the guage a bit…not sure if that’s what’s at play here. Sometimes just swapping ends, or positions in the consist, can make a huge improvement. I learned that lesson with Spectrum heavyweight passenger cars and their horrible coupling system.
Rich, I am on a few Canadian MRR sites and this topic has come up with the Super Continental Line often. Some of the guys have bought the new and improved trucks from Rapido when all else has failed and that solved the problem.
As much as I love Rapido and the trucks are not an expensive item, it grates me to have to spend money for new trucks from the same company to have a fix, however, if I cannot get the last two offenders rolling right I will order the new trucks.
“One other thought about the effect of swapping trucks is to take a close look at the truck mounting boss and the riding surfaces. It is just possible a particular truck is a tighter fit on one underframe than on another (or conceivably too loose?) and performs inconsistently.”
Be aware that ‘best performance’ will be with one truck laterally supported, and the other free to tilt laterally while supporting the end of the car at ride/coupler height.
Absent any equalization built into the trucks (or approximated by conical-end axle action) this implies that if you start to tip the car on straight track, both wheels of the ‘lateral support’ truck high side will start to come off the rail at the same point, with the other truck keeping all its wheels on the track until the angle of heel grows much larger…
This sounds eerily similar to the problem I was having with my Walthers Budd passenger cars which I wrote about in this thread:
Passenger truck recommendations - Model Railroader Magazine - Model Railroading, Model Trains, Reviews, Track Plans, and Forums
If you go to my last response, you’ll see that what has worked for me was to go with the longer Walthers trucks that I believe were intended for the lightweight Pullman cars. I’m not sure why they worked better but I suspect the added length of these trucks was the main reason they work better. I don’t know how that applies to your Rapido cars and whether the trucks are interchangeable with Walthers but if they are, you might give it a try.
I’m unfamiliar with the Rapido cars but I’m guessing there is a screw that holds the truck to the body. If that is the case, I would try adjusting the tightness of the screw. Maybe they are too tight. Maybe they are too loose. Compare them with the cars that aren’t derailing to see if there is a difference.
Yes, that was my feelings about buying new Walthers trucks for my Walthers Budd passenger cars. Ed was generous enough to donate to me a few he had on hand but I had to order a few more to get all the trucks replaced. It had to be done and once I was able to determine that the longer trucks solved the problem, it made the pill a little easier to swallow.
It’s probably a good idea to check the wheel gauge but I have to say that in all my years of checking wheels with the NMRA gauge, I’ve never once found any that were out of gauge. I’m wondering if that was a problem from decades past that has now been eliminated through better quality control.
This is from the Rapido product support page I posted earlier. I suspect the longer trucks would snag all the underneath detail and would be an issue. Note it says “some cars are equipped”. Does this mean it was a crap shoot as to what trucks the car ended up with during manufacturing? Pfzir or Moderna.[(-D]
41-N-11 Inside Swinghanger Trucks
Some cars are equipped with 41-N-11 trucks, also known as Inside Swinghanger trucks. These trucks have a longer wheelbase than the Outside Swinghanger trucks (type 41-BNO-11) that we also fit underneath our Super Continental Line Passenger Cars. Because of this, these trucks may need to have their ends snipped off in order to operate on curves between 22" and 28" radius. They will not operate on curves tighter than 22" radius without more major modifications to your car. It is best to test the car on your tightest curve, and cut off the ends if they bind on the underframe. Use a small pair of nippers or flush cutters, and snip off the ends at the grooves. You will need to remove the trucks from the cars before attempting this.
I had never heard this solution before but it makes sense. Does it matter if the laterally supported truck is on front or the rear? I’m going to guess that it needs to be the same on all cars.