Lionel 726 RR locomotive

Steam locomotive pilot truck wheels of are very light with no weight on them, so they derail easily. Diesels have all their weight on the wheels, so they are more difficult to derail. Try swapping the switch with another one if you can, to isolate the switch. Make sure the track is level and not twisted. Make sure the truck swivels freely underneath the locomotive. If the curve comes right after the switch, try swapping out that curved track with another one. Add a straight track before the curve to see if that helps. Check the gauging of the wheels also; if they are slightly out of gauge, that may cause a problem. Since this happens only after exiting a switch, check the transition between the switch and track to be smooth, and not have a bump, due to distorted rail ends.

Larry

Check the pilot truck for any bends or warping.

I recently had a similar problem with a turbine.

I know the trucks are completely different, but if a turbine pilot truck could warp, why not a 726 front truck?

Check the pressure of the spring holding the pilot trucks on the track, and also the spring holding the rear trailing trucks to the track. Possibly they both need more pressure on the trucks. Also, when the front pilot trucks go into the curve part of the switch, is there any guard rail holding the trucks in place? Just ideas..

Check the distance of the wheels on the pilot truck and gauge out the track as well. I have had a few where pilots in manufacture are too wide. Always fails on switches.

I had the spring break on an old loco's pilot truck, it just snapped into two pieces in the middle - no idea how or why and it is difficult to explain how it would happen.  But it did and started acting up just like yours - the pilot would derail at switches..  

Some of the things that I did to try to fix the problem:  Changed the curve track after the switch--this did not solve the problem.  Then I put a tiny piece of foam on the inside corner of the switch where the frog meets the inside rail in a straight position-still derailed.  I cleaned the switch of any and all grease or oil--it worked!  Took off the foam and it derailed again.  So I guess the tiny foam keeping the frog a small space out from the inner rail of the switch was necessary. I ran the engine around the loop and now it derailed on the next switch.  Cleaned that switch as well.  Then derailed on the very next switch.  There are a total of six switches on this platform, but the engine seems hung up on the three consecutive ones at the end of the platform.  As I mentioned, the one that gave me the trouble initially has been corrected; now, it's the next two.  I tried two different pilot trucks with the same result.

The pilot trucks you tried, are they new production or reproduction? the reason is the new trucks have a shorter rivet that hold the spring for downward pressure. The original one has a longer rivet. The shorter rivet version won't have enough downward pressure from the cylinder casting it rides on. Be sure to lube the rivet head so the pilot truck slides smoothly back and forth. Oil the axle in the casting also.

Using the diagram of the switch here, it sounds like you are talking about the swivel rail and not the frog. Note the frog is called the auxiliary rail in the diagram. If in fact your problem is with the swivel rail, is the rail loose and can it be moved by hand a little, or does it rock from side to side? You should not have to keep the swivel rail away from the long curved rail to get your locomotive not to derail.

Larry

OK, here's what's happening with this engine.  I purchased a repo pilot truck when this problem developed with the original one.  It made no difference regardless of which truck I installed.  Today, I tried running the engine again.  I thought I'd beat the problem with the original problem switch.  Alas, it derailed again despite my prior efforts.  I decided to place the engine on an entirely different loop, transferring it from "0" to "027."  This loop also had a switch but it was manual without any power to it other than from the track.  As the engine went around, it derailed at the switch just like on the other loop.  When I investigated the original problem switch 022, I carefully pushed the engine across the switch.  Where the swivel section meets the inner rail when in a straight position, at that point where the transition occurs the right truck comes off the rail.  When I push it backwards, surprisingly, it returns right on the rail again.  That is why I placed just a tiny piece of foam at the spot, to keep the slider rail slightly apart from the junction with the inner rail of the switch.  Once the engine clears the three problematical switches on one side of the layout, it seems to have no problem going on the other three switches on the other side.  I suspected an electrical abnormality but my experience with the manual switch on the other loop seems to negate that.  Anyway the old engine chugs along until it hits one of the three problem switches.  The flashing spark tells me that it has derailed again on one of those three.  Keep in mind that this has never happened before.

It seems that the wheels on the front truck may be slightly out of gauge. Carefully measure the dimensions between the backs of the front truck wheels and do the same thing for the wheels on the rear truck. Compare the dimensions. Try running the locomotive backwards without the tender and see if the rear truck derails. A clear, close up picture taken at track level of the front truck just as it derails would help. Also, since the problem seemingly occurs only on one side of your layout, is the layout completely level? Try turning the layout 180 degrees and see what happens.

Larry

I had extensive derailing problems with my front pilot on the 726 and the 2026.  For me it was the longitudinal gauge of the pilot wheels.  I had to very carefully tweet the inside dimension from flange to flange to get the right distance.  Both now run without derailing on any switch.  You will spend considerable time tweeking this because it is a very small adjustment needed.  To wide no good too narrow no good.... 

Don't give up, it will work. 

I was just wondering whether anything electrical might be a contributing factor.  Today I was showing my layout to some visitors.  Of course, the 726 was off the table and in its place was a diesel switcher.  The diesel negotiated the problem switches just fine except when I switched one of them to go around a curve rather than straight.  Somehow, the diesel kept on going straight and derailed

I see quite a few tips all centered around the specs of the pilot wheels and gauging of the switch parts including a very good one related to adding weight and how to do it.

Maybe I missed something but I don't see that you have validated these recommendations on you layout.

How about it?

Are you using track power or external power for your switches? If using track power and running your trains slow, the switches may not operate consistently. It sounds like the swivel rail did not throw completely that derailed the diesel. Suggest strongly to power switches with external power to assure best performance.

Larry

As far as the specs for the pilot wheels, unfortunately, in the process of doing that I bent the axle which I have to replace.  This engine seems to have the problem in just the same area of my layout regardless of what pilot truck I install--it doesn't happen elsewhere.  I suspect maybe weight distribution has something to do with it, but this oldtimer had the same weight distribution for years and didn't derail before.

All my switches run on constant voltage.  I did try to run the problem switch on track power by removing the plug from the switch.  I was thinking that maybe the entire train has to pass the preceding switch before I can change the one I want to switch or at least be off the preceding one at the time I switch because of the automatic non-derailing feature of constant voltage application.  My thought was that some electrical glitch was causing this.  When I stopped the engine, then did the switching, and started it up again, there seemed to be no problem.  In the past, I've noticed under certain unknown circumstances, a switch will automatically flip in an incomplete fashion as the engine rides over it, causing a derailment.

First, put a level on the layout and see if it is completely level, especially in the problem area. Next, turn the layout 180 degrees around if you can and see if the problem follows the switches, or stays in the same physical location. If a switch throws while a train is passing over it, it sounds like the non-derail feature is being activated. Make sure the insulating pins are in the proper rails, and disconnect the controller to the problem switch to see if this clears up the problem. Also check that the swivel rails are tight and cannot be moved at all by hand. Swap out a problem switch with another one to see if the problem follows the switch or not. These suggestions need to be done to narrow down the problem, or it may never be diagnosed.

Larry

O.K., I think I have the problem solved (at least for now).  I spread apart the wheels on the pilot truck axle a bit.  Then engine rode over the rails for 20 minutes without a derailment.  Thanks to all for your suggestions!  Mission Accomplished....

Yeah!, bout time!

It's amazing that if you approach a problem systematically and try the simplest solutions first how easy these trains are to fix.

jackson