I have a Lionel 726RR Berkshire Steam locomotive (2-8-4) that derails when going over 022 turnouts. The stock rails on the turnouts have little grooves cut in them to allow the switch blades to rest flush with the rail. The pilot wheels of the locomotive appear to be following this groove up onto the rail where they then derail to the outside and the axle creates a short. This only occurs if the train is coming from the straight side back onto the main line. I have a left and right turnout and this problem occurs on both. Everything ran fine 3 weeks ago, but when I set it up again a few days ago I can't get past this problem. Any help is appreciated.
The pilot truck derails after the locomotive enters the turnout in the trailing-point direction on the straight path. Is that right?
To which side does the truck derail on, for example, a right-hand turnout? Is the last track section before entering the turnout straight or curved? If curved, in which direction does the locomotive turn before entering, for example, a right-hand turnout?
At the position where the pilot wheel's flange picks the notch in the rail, is the truck axle perpendicular to the rails, or is the truck steered somewhat in the direction toward the notched rail?
Bob Nelson
The pilot truck only derails after the locomotive enters the turnout in the trailing-point direction on the straight path. That is correct.
On a right-hand turnout the truck derails to the right side as seen from the direction the engine is coming. On a left-hand turnout it derails to the left side. The three track pieces before entering the turnout are all straight.
When the wheel picks the notch in the rail the truck starts steering towards the notch. As the wheel rides up the notch, the opposite wheel comes of the other rail.
Thanks for that clear description. I think the problem must be in the locomotive, for it it occur with either-hand turnouts.
But the only thing that comes to my mind is that perhaps the pilot-truck gauge is too narrow. If so, the turnout's guard rails may be consistently steering the pilot truck off-center enough for the flange to catch the notch. If you can move the truck more than a little side-to-side on straight track, maybe pulling the wheels outward to close-up (but not eliminate) the clearance would do the trick.
Also check the pilot truck over. Just recently I had a Postwar Berkshire on my desk that had a badly warped pilot truck frame. Maybe yours is a little warped. Also check the wheel set. Do they turn straight? If the axle is bent, that might cause a derailment at switches. Finally, are either of the wheels damaged?
The axles and wheels are in great condition. Not bent or damaged.
When on straight track the truck moves side to side quite a bit. How would I move the wheels outward? I have space on the axle to do so since there are not side frames.
You really need a wheel puller to do that safely. With drivers, it's often possible to get them off without breaking anything by prying with a screwdriver between the wheel hub and the bearing. You could try that here, keeping in mind that the truck frame is not as substantial as a motor frame.
I would take one wheel completely off so that you can add shims (washers) to keep the wheelset reasonably well centered on the truck. You can easily press the wheel(s) back onto the axle with a bench vise and a couple of short pieces of metal tubing fitted loosely over the axle ends to center the force on the wheel hubs.
I have a piece of scrap metal with a slot that slides behind wheels such as as your pilot truck wheel set. Then I tap the end of the axle with a light hammer. Never had a problem yet. My wheel pullers won't go small enough for a pilot or trailing truck wheel. I suggest comparing the spacing of the pilot truck wheels to the trailing truck wheels before you do anything. Another option would be to leave the original pilot truck alone, and try a reproduction to see if the problem remains.
One thought you might try as a test:
remove the lead truck, and roll it through the switch by hand. Then, you might get a sense if it is a gauge problem, or something else. It could for example be spring tension, or limited vertical travel of the truck
I have the 726rr, and it is a wonderful engine, but mine is prone to derailing the lead truck on a 30 degree crossing. I wrote it off as being a long wheelbase engine. And 2 wheel lead trucks are notorious for jumping in all scales.
I would be interested to know if you can resolve it.
But try to roll the truck through by hand...
With regards to my 726rr:
I discovered that the 30 degree crossing has a significant hump at the frog section. As the Berk passes over the hump, and the front drivers are on the hump, the lead truck lifts off the track. There is not enough vertical pivoting for the lead truck to remain on the track, hence the derailments.
So , you will need to determine if it is a gauge problem ( "picking" the switch), or something else, as in my case.
Thank you all for your help. I was able to use a screwdriver to carefully pry off the wheels and respace them. They must have wiggled themselves in overtime because everything works fine now. I have ran it through both turnouts several times, even at full speed and it hasn't derailed again. Thanks again for the help!
Great news! That's fantastic !
I guess I'll have to go back and take another look at mine !!!
I'm glad to know that it worked. You're welcome!
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