Can't run Aerotrain Cars in reverse - derail

Stur-it,

Thanks to your posting of your Aerotrain passengers, it reminded me that you have the train.

Can you back your train up?? Around 42" and/or 54" curves in particular.

If you haven't tried, could you and then let me know?

thanks - walt

Is it the observation car? I have a set of RailKing streamline passerger cars, and when backing into a spur that has 036 curves the rear coupler, not being attached to another car and thus not pulled into the curve, would move out and into the skirting and thus not allow the truck to turn enough for the curve, resulting in a derailure every time. I removed the coupler to solve the problem.

Hi Walt Not going to be much of a help with this I never back up my trains They are always going forward. Hope someone out there can give you some ideas on what could be the cause of this.

stur-it: thanks for the reply but could you try?

Jeff, no it's not the observation car, if that's what it's called in the Aerotrani. BTW: the trailing car only has one coupler and can't be turned around.

There are 2 cars making for only 8 way to combine them. I've tried all 8 and none stops the derailing.

- walt

Is the derail caused by leading (when in reverse) outside flange climbing the rail?

If so, after making sure that the truck swivels as freely as it can, check to see if there is any burring of the flange or even a too sharp (not rounded) edge.

If the derail is on one of the trucks that is coupled to another car, I'd bet that coupler shank is interfering with the truck.

--Joe

Joe,

The Aerotrain cars don't have trucks. They have single fixed axles, like a bobber caboose has.

The train hasn't caused me any issues running forward, probably because of the direction of the pressure on the car, or in the case of running foward, the lack of pressure on the car.

Since my layout is now down, if I can't resolve it before York, I will take it to York and show it to whomever at MTH who might be able to comment and help. I might also show it to the vendor (who is a LHS proprietor) that I bought it from and see if he can determine the cause or replace the car.

Thanks for trying to help out!

- walt

Sorry, I'm unfamiliar with Aerotrain. I didn't even think to check online.

So, which axle derails (going in reverse)? Lead, trailing first car, or second car lead? Was it climbing the outside rail?

Is there any fore-aft play in whatever anchors the axles? Are these needle point, fast angle wheelsets? Lastly is it possible that the axle is not perpendicular to the car axis?

I can see why you're looking for someone else's first hand exprience.

--Joe

Joe,

The axle that derails depends on which way the car is oriented. The INSIDE wheel seems to lift up off of the rail and then when it settles it's inside the rail and derails.

Like I mentioned, I held the car up, wheel to wheel, with the other 2 cars and the wheel flanges match up.

Unless the car was constructed wrongly I don't see how the axle could not be perpendicular to the axis of the car. I may disasseble the car and see if I can remove the axle to see if I notice anything.

Hey, thanks for trying to help!!! I appreciate that.

- walt

Just an idea. Put a straight edge on the inside of the flanges front wheel to back wheel. If a wheel is toed-in it would probably roll OK in one direction, but not the other.

Just a thought.

I have a loop on our Christmas display at the store with Fastrack 036/048/060 curves. While it really wasn't too happy on the 036 (pinching the wide diaphrams), as far as wheels go, it was able to make the entire loop in reverse without derailment. Also, do you have the wide or narrow diaphrams on your cars?

Gilly

Walt

Put the offending coach on a dead level surface (like a glass table top) and see if all four flanges touch the ground. If they don't then unscrew the offending truck block, look for any burrs or flashing, remove them and put the truck block back.

Also, make sure the pickup roller is not raising the truck off the glass. Again, put it on the glass, and compare with the other coaches

John

Thanks for the suggestions Gilly and John. I will try both.

Gilly, thanks for confirming that yours runs fine in reverse. Now I know that it can, and on curves sharper than what I ran mine on.

thanks again - walt

Walt, tried mine on my smallest radi (Atlas nickel 36") no problems in reverse and that is with an 8 car consist, however, I don't use turnouts anywhere on my layout. Did you test the offender going in reverse without involving a turnout?

Stack

Stack,

Thanks for trying and giving me the low-down! Yes, I tried it on 42" AND 54" curves where no switch was involved.

thanks - walt

John: did your test: the 4 wheels all touch the table top. BTW: since the car doesn't have trucks, the roller isn't involved. But I did make sure that the roller isn't preventing either axle, front or back, from settling correctly. it's not a factor.

Gilly: did the straight edge test and as best as I can see the front and rear wheels line up perfectly - on both sides of the axle.

Maybe I just have to resign myself to never backing up this train - which hurts in designing things for my Christmas layouts since it always involves dead-end staging.

- walt

You might try adding some weight to the car(s). Also, check the depth of the flanges. The flanges ride the ramp and support the car/wheel as the wheel moves over the gap in frog. That's the cast metal piece where the short rails cross in the turnout. Also, with only one pair of wheels instead of two the axle ends may have too much front-back motion which might let the wheel derail in the frog. Also check the clearance between the rail and the guard rails.

Jan

Thanks for the suggestions Jan.

The problem, though, is NOT on the switch. The derailment occurs on regular curves even where the is no switch. It hasn't yet derailed on the 42" switch itself.

thanks - walt

quote:

John: did your test: the 4 wheels all touch the table top. BTW: since the car doesn't have trucks, the roller isn't involved. But I did make sure that the roller isn't preventing either axle, front or back, from settling correctly. it's not a factor.

Walt,

Thanks for reporting back. That was the most likely culprit. By the way, I am aware the Aerotrain does not have trucks per se, which is why I refered to them as "truck blocks."

The problem with the Aerotrain coaches is they are basically a rigid box sitting on four unsprung wheels. There is no suspension or flexibility at all. So modest changes in rail height from one side to the other, or an abrupt height transition from one section of track to the next, or even a slight change in gauge of either track or wheels, can throw the thing off.

So here is where I would go next

1) Double check that this does this on all your curves, particularly those with track joints. Your gentle push method works fine. If its OK on some, and not others, then supsect your track work. Also, don't discount the third rail. Even a jolt to the roller can push it off

2) Double check the width between wheels. I know you said you did, but make sure.

3) Spin the wheels to make sure they run true. And they easily slide from side to side

4) Repeat my "sitting on glass" test with a piece of track. Make sure the coach does not rock in any way, and all four wheels sit squarely on the track.

5) Make sure the coach does it by itself, not coupled to anything (I asssume this is how you are testing this, but just to be sure.) If there is a car in front, suspect something preventing the coupler from swinging freely.

At this point, things get a bit more complicated

6) Remove the roller from the offending truck block (its a simple screw). Replace that screw with a washer underneath to prevent the connecting boss from falling into the truck block. See if that solves the problem. If it does, find another roller.

7) If it's not the roller does not, swap the entire truck block with another. You have to remove the shell. If you are uncomfortable doing that I can send you step by step instructions

8) If none of the above work, you are welcome to send me the coach, and I'll take a look at it. You will also have to send me some sections of your track. I am fairly familar with the Aerotrain and might be able to fix it

John

John,

WOW, way more than expected in terms of help!!! Thanks for taking the time.

I can't recreate the exact situation since my Christmas layout is now torn down. But as I think back as to what happened, and WHERE I do recall it derailing in the same exact 2 spots every time. One was on a stage track on a 42" curve and the other was on the main using 54" curves.

Because I knew it had problems backing up I only had these 2 places to test on. The other places, if the train derailed, would have been problematic to get to so I didn't back it up in those spots.

But the derailment was always at the same exact spots so maybe 2 pieces of curved track weren't perfectly "flat", as you list as a possible cause.

I got out some 42" and 54" curves last night and did the "gentle push" test a bunch of times. Some times I pushed just the one car, sometimes I coupled it up, I changed the orientation, etc. It never derailed. So maybe the track was the culprit.

Funny though: it was always the same car. The engine never derailed, nor the other 2 cars. Always the same car. You would think that if the track was the culprit that one or more of the other cars should have derailed too. But no.

BTW: I also ran another train on that trackage when my layout was up - it was a freight train using all MTH cars. It had NO problems backing up thru those same curves.

Taking all of the above, that's why I suspected something with the car itself.

Now that I can't re-create it I guess I'll have to hope and remember to test again when I set up the layout again. The track configuration will be different but that shouldn't matter.

John, I will keep your thoughts and offer in mind when I set up again after York October. I will make it one of the very first things that I do - test the train. For now I am going to forgo dismantling the car. If it happens again when I set up I will do it then.

thanks - walt

Walt,

Maybe it took a combination of things of two or three things to cause the car to derail. For example, the track gauge being too narrow and the wheel gauge being too wide. Or the other way around.

Jan

I have an Aerotrain and when I first got it I would derail on one particular curve almost every time, a curve that everything else ran through flawlessly. After careful study I discovered the outside rail was slightly lower than the inside rail. The obvious solution was to shim the outside rail slightly (Super elevate). Problem solved.
Remember, cars and locomotives with a rigid wheel base have a tendency to clime over the outside rail

Richard: what you described

quote:

cars and locomotives with a rigid wheel base have a tendency to clime over the outside rail

is what my car was doing. The inside wheel would rise up and move "inward" in a certain spot. When the inside wheel descended back down it would still be inside the rail, thus the derailment.

I wish, in a way, that my layout was still up so I could test out some of these things!!!!!!!!!

I still am struggling though with why only the one car had an issue. Everything that I've checked on that car (based on suggestions here) checked out OK, including the gauge of the wheels.

I can't wait to set up again and test this all out. I will print this thread and refer to it in November.

thanks - walt

John and/or Richard:

I was in the process of doing a cut-and-paste of comments posted here into a document that I already had created dealing with Aerotrain comments from when I first got the train in 2010.

I saw this comment in my document:

quote:

Walt, the engine has plenty of power but the cars didn’t roll easily. I had to fiddle with and lubricate the axles to get them to roll well. Because the cars have only 4 wheels they tend to derail anyplace you have mediocre track. The thing to watch for is a front wheel climbing over the outside rail on curves . You may find yourself with a track improvement program. I have a 5% grade on my layout and the Arotrain runs up the hill with 5 cars without any problems

(emphasis mine)
I wonder if it was made by one of you two? I should read my notes more often

- walt