I’d appreciate advice on an issue I’ve discovered. I was testing my newest trackwork and discovered my BLI Mountain 4-8-2 Paragon series with Quantum DCC (booklet dated 2005) derailed going backwards through a joint connecting my 7-1/2 curved turnout with a flextrack curve of about 25"r. I found the joint is VERY slightly kinked, so thought the solution was re-doing the incoming curve, which I plan to address.
With more testing, running the Mountain backwards around the layout, I found the back driver axle can tend to find places in curves where the outer flange climbs up over the rail. It does this in several places, an example being backing through another 7-1/2 turnout, on the broader curve, about 3 ties before encountering the frog where no guardrails are present. A trackguage shows the track is certainly not too narrow there, and the curvature is not that severe.
None of my other rolling stock (e.g., my BLI Mikado), forward or backward, derail at any of these points.
I checked the driver wheels with my NMRA guage and noted that the flange span is not too wide (which would lend towards this). But, the back driver axle is the one with the rubber traction tires, so there’s less flange depth than the other drivers, though it barely passes the guage test.
I don’t feel like trying to attack multiple track areas (will address the slight kink area) if the loco is really too sensitive to derailment and should get some attention. Would switching the axle to the provided non-tired axle (or to the 3rd axle location) likely solve or reduce this problem? Not sure I could do that myself unless someone can advise on the procedure as I don’t want to break the brack assembly details (do they pull out?) that have to be removed to free the axle.
i don’t have any engines with traction tires but, i would bet that anything that interferes with the lateral motion of the leading driver is a recipe for trouble. when backing, the rear drivers are leading.
logic says, if only one piece of equipment is derailing, then, the trackwork is not the culprit. that is not to say that sub-standard trackwork is acceptable, just that you can get away with a few imperfections so long as the combination of bad track and sensitive equipment doesn’t cause problems.
i thought my trackwork was almost a work of art for years until i started trying to run some of my older long wheel base brass steam. was that ever an humbling experience.
Paul I had the same problem with my BLI 2-10-4. I found the cause was a slight dip in the rail on one side on a large sweeping curve. I use this level and slide it slowly along the track looking for small changes in the bubble position. I have pencil marks on the glass.
In the other spot it was also on a curved turnout. I had to video tape the engine rolling over the spot and watch it on the big screen frame by frame. I noticed the track would sink ever so slightly as the engine would roll onto that spot.
In both cases the fix was easy once the problem was diagnosed. So don’t get too frustrated.[:)]
Derailments are very rare for me. At times a guest has been known to place an elbow or heavy object on the layout that can cause an issue. Usually the fix isn’t much more than a couple of minutes work. Caulk makes an excellent leveler.
Brent, I found my little level and see that what you point out is contributing to the issue at the first spot the trouble surfaced. I loosed the track and shimmed it temporarily, which reduced but did not yet eliminate the problem. I’ll keep at it. Thanks for that lead.
Charlie and Brent have good suggestions, and Charlie is dead on when he says that it’s almost certainly the engine. My preference in a situation like that would be to replace the traction-tired driver set. If the engine is then seriously traction-challenged, add more weight over the drivers, or in extremis, apply some Bullfrog Snot (I love that name! [:)]) to one of the two inside driver sets. Be sure to add it to both wheels on the axle.
Many of the BLI engines from the mid-2000’s came with a traction tire installed and a steel one included in the box for convenience/preference. Or, if they had a flangless driver installed, one with flanges was included.
If you are stuck with no swap-out option, then I would place the traction tire in the position of the one other driver set that does not have the main crank and that is not the lead driver when the loco is moving forward.
I believe that this also works for flangless tires as it does on the prototype. The two outer drivers have to have flanges for reasons that should be intuitive, and in the case of our models, the traction tire should be inboard of the two outer driver sets to allow for some sliding of the tire surface along the rail head surface during negotiation of tight turns. Rubber tires will make this most difficult.
The changing of the drivers will be a bit involved, certainly for someone who has no experience at it. First, if other drivers were included, so is/was/ought to have been a nut driver to loosen the nut holding the main rods and side-rods in place on all the cranks. The rod has to come off, the brake rigging my have to be displaced or removed, the gearbox cover removed, and then the drivers will have to be lifted and swapped in the two cases. Keeping crank position in mind (the gearing should help with alignment when you insert the axles into position), reassemble in reverse order.
NOTE! There will likely be at least two sprung axles on the loco. You’ll know if you find one. Be careful of the tiny springs. Seat the axles carefully and give them a tiny bump with a finger-tip to ensure they spring easily. Gently and patiently wiggle everything into place, insert the nuts, tighten, and restore the rigging and nether plates.
Note: You will want to check the nuts after a short p
One other thought I had. I have several curved turnouts on my layout. A few years back I discovered my new BLI was torquing one of the curved T/O’s out of gauge when the heavy loco hit it at speed. I don’t usually caulk my T/O’s down, however this curved one performed flawlessly once it was secured firmly to the cork road bed.
I’m inclined to address the drivers first, then the track (any remaining hiccups). The loco came with the plain spare driver and the nutdriver that Crandell mentioned. Getting the one piece plastic brake assembly off looks to be the mysterious part. It covers the journal cover screws, so I wonder if it is press fit in?? I can’t imagine they would glue it in since it hides the screws. If I can get it out without feeling like it will break, I may give this a try (watching out for flying springs!!).
UPDATE: Started to pry the brake assembly off and some of it did not want to come. Will take it to my (25 miles away) LHS repair guy I think to swap to the plain driver or move the “tired” one to the middle.
One thing, if prototype fidelity matters to you is the position of the drivers. They have replicas of the counter weight cast into the drivers and are deigned to be placed in specific positions.
In running some of my Broadway Limited Steam Locos I have found by adding weight inside the boiler and in the firebox area around the motor I have greatly improved tracking of the models. In the case of 2 2-10-4 J1 Pennsy units I have added about 5 and 1/2 ounces of lead to each and made some adjustments to the spring pressure on the front truck and the loco pulls very well and tracks beautifully, with out traction tires.
With out traction tires I was able to pull 50 cars up a curving 2% grade quite well. I would recommend replacing traction tired drivers with the non traction tire type and adding weight if at all possible.
A great source of lead can be found by A-line in your hobby shop and a much more reasonable source could be found in cast offs from roof vent stacks as the older ones are lead. Shaping the lead is quite easy with a hammer and a solid surface to rest it on while hitting it. Just remember it takes trial and error to make sure you have a good fit.
Bending some of the sheet lead into a U shape that can be temporarily placed on top of your locomotive will allow you to see if adding weight improves the issue you are dealing with. In my case the difference was so noticeable that I weighed the piece of lead and found places to install the weight inside the loco.
Paul, if the springs and brakes are attached the same way they were on my 2-10-4s they can be pried loose after removing a few screws from the bottom of the loco, if I remember correctly the pilot truck needed to come off and then the spring and brake casting could be gently removed from the holes it resides in.
I have several BLI steamers, all Paragons, but none of them are the 4-8-2 Heavy Mountain.
Steamers can be finicky and BLI steamers are no exception. If it is the only locomotive to have difficulty negotiating your track work, it is logical to suspect the locomotive before the track work.
But, in my experience, I have had one steamer derail where no other steamers wouid, but that same derailing steamer would run fine over other parts of the layout where other steamers would derail. I just think that is the nature of HO scale steam engines.
I doubt that the traction tires are the problem.
When you mention running a steam engine in reverse over a curved turnout, I shudder. Running a steamer in reverse is already fraught with danger. Running a steamer in reverse over a curved turnout is really asking for trouble. So, I suspect the curved turnout.
In my experience, a curved turnout is big and flimsy. It needs to be stabilized on the layout. I secure the two curved layouts on my layout to styrene sheet for added stability. The rails must be perfectly level and the turnout cannot be allowed to float. If one rail is slightly higher than the other rail as the engine passes over the turnout, it will surely derail, even more so in reverse.
This morning I ran the Mountain around backwards some more. I identified 8 places where the cab end (leading, in reverse) driver climbs up and derails, all at 7-1/2 curved turnouts. I’ve decided to take a positive approach to this and address each as an improvement opportunity. If I can’t get them all to work well for this loco in reverse (it does fine going forward), I’ll at least improve track that does ok for everything else so far and heighten the trackwork quailty for more sensitive locos. There are a couple of areas I will work hardest to make work for backing this loco, as it (and others) need to be able to back out from a loco shop, etc.
I did lightly secure my turnouts with a bit of caulk, but I did not check any track for “level” as described above, so some shimming and re-securing might be called for, which can likely be done without disconnecting any track.
I’m currently undecided on whether to try the driver swap to non-tired type, or moving forward if feasible. I won’t try that myself. I think I need to progress the trackwork first and then reassess whether the loco might be helped. I wonder if stronger springs on the back axle could help.
One other suggestion, maybe it was already mentioned, but when I have tender issues, one of the first things I do is adjust the drawbar from loco to tender. Sometimes a slight adjustment can keep it from riding up. If everything else runs properly, and you have to assume it’s the loco, this is an easy way to possibly correct the problem.
One point of advice that I might be able to impart. Before investing a lot of time in trackwork or messing with the drivers of the engine, check the spring for the trailing truck. I’ve encountered this problem with BLI steam locos with 2-wheel lead trucks. The spring may need adjustment moreso than anything else.
It could be the drawbar. it could be the spring on the trailing truck. Both are good suggestions, and I have done both of these in the past to correct problems on my BLI steamers.
But I still suspect the curved turnouts. Curved turnouts are notoriously flimsy, and the weight of the loco can easily force one of the rails higher or lower than the other. I recommend stabilizing the entire surface of the curved turnouts.
Flip up the deck plate on the engine and see how it goes. This caused me some grief on a tight curved turnout. Coupling the tender and engine further apart solved the problem.
My N scale Bachmann Heavy Mountain did the same thing, although on 9-3/4" curves. I removed the traction tire and replaced with a Kato driver, and everything works well now.
Remove the traction tire and try to see if that works. If that doesn’t, tinker with the lateral play of the last driver. That could be the culprit.
