Left Turn Issue, MTH Mikado

GRJ, RoyBoy may have a point.  Something wrong with the front truck could be lifting the right side.

Have you precisely measured the front drivers to make sure they are precisely the distance apart as the rear drivers, and are you sure the right front driver is directly in line with the rear driver?

I have run it without the front truck, that didn't change anything.  I'm going to give it a try on the Atlas track on our modular layout next.  Maybe I'll bring it down to Pat's place on Friday and see if it runs there.

I'm sifting through all the suggestions, but I don't know that I'll get to this until after the TCA Convention at this point.

John, Add some weight to the front and you will solve the problem.

As I mentioned, that's easier said then done.  Also, since others have the exact same locomotive without this issue, I don't think this is as simple as not having enough weight in front, even though that might hide the issue.

A couple years back when it was difficult to get traction tires from MTH I recall getting a few that seemed a little off, in that the thickness wasn't uniform all the way around. The difference wasn't obvious and I probably wouldn't have noticed without my glasses on. I never used them and believe they're still stashed away in a scrap box somewhere so I don't know if that could be an issue.

When I run it on my roller blocks, it's as smooth as butter, I took particular care in checking if there was any bobbing and weaving while it was running.  Inspection of the tires also didn't reveal anything.

I had a similar problem years back and it turned out to be the track itself, there was just the slightest dip in the railhead, almost unnoticeable.  I had never thought of the track as I had no problems with other engines, upon laying a straight edge on the rail head there was a dip just going into the curve and once I tweaked that the engine never derailed again...such a weird experience.

Since it derails on every left turn, I did discount that, but I'll check anyway.

This may be a long shot, but could the quartering be slightly off on that pair of drivers?

Anything's possible Nicole, I'm trying to go through all the possibilities.  Obviously, something is wrong.

Good afternoon John

Can you get an overhead aerial look ? Operate the locomotive on a straight track and look down to see if it is dog tracking one way or the other. I had a Mikado with this problem but not as severe as yours. One rubber tire was thicker than the other. Didn't like 11 degree crossing.

Clem

I like Pat's idea, but I would add that if it works on Pat's layout then bring his engine over to your house to see if it acts the same way.

I know it's a long way to go but I personally never saw this particular problem before. I have seen obscure track issue effect one engine and not another and when I finally found the cause I was always amazed that I failed to see it immediately.

(1.)  Sprung drivers. Reverse left/right springs, one may be weaker than the other. Possible broken spring.

(2.)  Bent frame ??? Slight twist with less pressure left to right.  It may have been dropped.

(3.)  Loosen shell screws from the frame.  Torque-ing the shell to frame screws may be causing a twist. 

(4.)  Axle movement left to right. 

(5.)  Check the inside of each flange.  I had a chuff magnet that was not flush on the inside of a driver that would lift on guide rails, switches, and crosses. 

(6.)  Quartering needs to be checked, has been mentioned. 

(7.)  Tender tether problems, has been mentioned.  

(8.)  Trailing truck on the loco.  As the loco body swings out it may be catching causing the derail.

(9.)  Check the swing spring tension on the trailing truck.

(10.)  Front pilot, has been mentioned.

(11.) Check the tender trucks for free operation. 

John,

Have you changed the drawbar yet? Longer drawbar solved derail with my Imperial 4-8-4 turbine.

S

Also check the drawbar spring at the engine side. Sometimes they get misaligned and do not flex.

As it turns out, Harry Henning III solved the mystery.  The locomotive is the switchable 2/3 rail, and the drivers have a different profile than the straight hi-rail wheels.  It runs perfectly on Atlas track, and he said he's seen this with a number of the newer MTH locomotives and Fastrack.  They run fine on flat profile track like Atlas or Gargraves, but not so good on Fastrack or tubular track.  I ran it around for about 20 minutes at all speeds, never an issue at any time in the run.

Mystery solved, but I'm not sure what I do now about running it here!

Had a similar problem with the trailing truck on my Mikado. The problem was the elongated swivel hole. I put small slivers of rubber tubing on the sides to act as a centering spring to keep the pivot centered. You might be experiencing something similar with the front truck since it also has an elongated pivot hole.

The problem is when it gets off-center, the flange edge scrapes the inside of the rail and climbs over.

"The locomotive is the switchable 2/3 rail, and the drivers have a different profile than the straight hi-rail wheels.  It runs perfectly on Atlas track, and he said he's seen this with a number of the newer MTH locomotives and Fastrack.  They run fine on flat profile track like Atlas or Gargraves, but not so good on Fastrack or tubular track.  I ran it around for about 20 minutes at all speeds, never an issue at any time in the run."

I had thought that having a -1 at the end of an item number that the model would be able to negotiate tubular track.  I thought that only models that have a -2 have scale wheel profiles.

So does this mean that all switchable 2/3 model have these scale wheel profiles and will not negotiate tubular track?  Is there a disclaimer on these models to this effect?

Steve

The problem is, this happens even if I remove the front pilot wheels totally.

All I know is this make it around a rather large layout with Atlas track without missing a beat, with or without a load of cars behind it.  Harry told me that this isn't the first time he's seen the same issue with newer MTH stuff.  The wheels don't look that different, but obviously there is something to it, as it's only the Fastrack it doesn't like.

I'm planning on digging out some tubular track and making an oval to test it, just out of curiosity.

It could be weight, though the drawbar is free and the spring doesn't seem to exert any undue influence on the rear of the locomotive.  I suspect if there was room, adding weight to the front of the boiler would be a good thing, there's not much room in there.  I may try to add a few ounces of weight to it right at the boiler door and see if that helps.  The headlight is kinda' dim, so I have to get in there anyway and I think it'll get an LED headlight.

The flanges are slightly smaller than the older strictly 3-rail stuff, but I didn't think that would be that big a factor.  I was obviously wrong.

Good morning

John could you post a photo of the two different 3 rail wheel flange sizes ? Im curious, does it make the locomotive look better?

Clem

It's pretty subtle, I believe it's just enough for it to run on 2-rail track.  The hi-rail flanges bottom out on switches.

No, 2R or 3r is not the issue.  It is scale wheel issue versus high rail wheels.  G

John,

I decided to remove the traction tires from the rear set of drivers on my Premier Angus to see if it stopped the derailing when I went thru the O72 curves in reverse. Guess what, it did. The drivers seem to want to shift a little bit as they enter the curve. I think the tires were not allowing the drivers to move and the engine was riding up the rail. At any rate it worked. You might want to try this on your Mike if you are still having trouble. 

Ken

The problem is the wheels.  I did actually try removing the traction tires.  It didn't derail, but it also couldn't pull five passenger cars on level track very well.

It runs great on the Atlas track on our modular layout, so I suspect this is a club locomotive.