Well, I decided to dredge this back up to report on my progress with this little problem.
Long story short, I couldn't find the problem. Since the issue was only with one engine on one stretch of Ross O72 track, after measuring everything (all looked fine) and trying to spread the rails a little (with no change) I just threw up my hands and replaced four sections of track, and the problem went away. I've looked at that removed track from every angle under the best light I have, and it seems absolutely fine to me, so......"I dunno." But it's working fine now!
Last night I did some experimenting with the 1225 and identified two specific spots where the wheels climb over the rails -- they are indeed on O72 curves. If the engine's running at speed, it will derail about half the time in those spots, and at a crawl it will climb out every time. I'm going to keep fiddling with it and see if I can find any more specific trouble spots. I need to turn it around and see if the problem happens when going the other direction too. Thanks for the insight.
The reason I asked about the truck wheels is that Lionel tended to get the geometry wrong for 2-wheel trucks. The truck pivot should be about halfway between the truck axle and the middle of the drivers. If it's farther back, the truck understeers, and, if it's farther forward--the usual error--the truck oversteers. This makes it want to climb over the inside rail on a curve, especially if there is any irregularity in the rail that the wheel flange can catch onto.
This may not explain your derailing, because your O72 curves should mitigate this problem. However, if you notice that your derailments tend to be to the inside of curves, that's a clue that oversteering is the culprit.
Bob Nelson
Both locos are Lionels, one is a Pere Marquette 1225 (not sure of the model number) and the other is a Milwaukee 8693, Lionel model # 6-81038. They both have two-wheel pilot trucks.
What locomotive numbers? Two-wheel or four-wheel trucks?
Hi everyone, I'm mostly a lurker here but I need a little advice.
I'm working on a new layout. I am using Ross switches with DZ1000 machines, and Gargraves track. My tightest curves are O72. The overall size is about 35' x 16'.
I'm having trouble with the pilot trucks on steam engines derailing just at random spots. It seems to happen at two or three vague areas on the layout, but I cannot seem to narrow it down or find anything out of whack on the track in these ares. The derailments don't seem to happen on switches, either. What can I look for--- what causes just the pilot truck to jump the rails?
Of course the wheels come off the track but the train moves a few feet before the short-circuit happens, so it's hard to nail down exactly where it's happening... one of my "suspect" locations is inside a tunnel, naturally.
And, I have ONE switch (out of 9) that seems intermittently sluggish -- sometimes it will only move the rails halfway, which then causes a derailment. And it doesn't operate with a "snap" the way the rest of them do. There is another switch right next to this one that works perfectly every time. All the wiring seems fine, but what else could I look for?
Any advice would definitely be appreciated. I'm hoping to put up some pics at some point... I'm photographically challenged, it seems.
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