Diagnosing the 2-10-0 stall

[Irbricksceo]

Hello, so I'd like your help diagnosing this. First of all, a video of the problem:

https://www.youtube.com/watch?v=sCZCgfwwues&feature=youtu.be

the problem is that clicking noise and the visible rock. sometimes the loco will actually stall and I have to kinda wiggle it around to get it moving

Now, some testing has revealed:
It only happens going fowards, never in reverse
It only happens going counter-clockwise
it only happens on the outer loop, and only on the section I filmed it on (not on the other side of the loop)
it always happens at the same point on the driver revolution.

Also, just to say, this is the later spectrum release with sound, though I took the sound decoder out because for some reason it kept loosing power.

Any ideas?

[jonathan]

IRBricks,

I watched your video many times.  One clicking sound reminds me of a pick up brush out of position. 

Another thought:  have your checked the drive belt?

Really I'm a bit stumped, but if it's happening only in one area of your layout, that's usually a sign track problems, not the loco.

Sorry I wasn't any help.

Regards,

Jonathan

[Irbricksceo]

No problem. I haven't checked the drive belt because, tbh, I cannot figure out how to disassemble the 2-10-0. I also suspected track issues but no other loco does this. That said, the fact that the problem only happens there means that something about that stretch IS different enough to trigger the issue. all I know is that the back of my table is slightly higher than the front, however that wouldn't explain why it doesn't do it on the inner loop. This is definatly a tough one.

[jonathan]

OK.  Let's assume the loco is leaning ever so slightly to the right as it passes over this section of track.  I have had a loose valve gear problem in the past, when some dangling valve gear parts would bump into each other and/or potentially lock up.  Easy solution was to put a slight bend in one of the rods.  The rivets and screws were fine.

If this is the case for you, the drive mechanism, on the LEFT, could be snagging as the locomotive leans to the RIGHT.

Just a thought.

Regards,

Jonathan

[jonathan]

After watching your video a few more times, the click timing is right for this diagnosis. 

Regards,

Dr. Jonathan

[on30gn15]

I'm of the mind that that sudden reversing won't be doing the drive train any good.

[brokenrail]

Believe that is what caused the problem.The answer to the problem is in the comments.
Johnny

[Trainman203]

Man you are running that engine so fast it's hard to tell if the click is every driver revolution.  I do believe that it is though.

I have 5 decs and every one has had this problem.  The cylinder block is not precisely engineered. Each piston rod is a little too close to the center of the engine.  With that, at each revolution, at least one side rod at the no. 1 or even no. 2 axle would hit the cross head.  In the worst case it would cause a complete bind up.  

In your case it could be that the clearances are ok except that in your special cases, something is edging one driver to one side just enough to slightly clip the cross head.  This could be a very mild example of the problems I had.

The only way to fix it is to bend the cross head guides slight outward toward the rear of the engine to get clearance.  It looks really weird when viewed from under the bottom of the engine but at normal sideways viewing you can't see it.

It took me a long time to find this problem.... I returned a few engines in the process before I figured things out.

This cylinder block piston spacing issue is one I hope gets resolved if the decapod, a most beautiful engine, is ever issued again ..... Along with getting the stock setting cv's set right for smooth operation, they come at terrible settings.  Between those two operationally critical  issues, I can't imagine how many of these otherwise top notch engines were junked either by the owner or by the service department.

[Irbricksceo]

Well everyone, Thank you for your help. I made several adjustments but I think the one that did it was putting a precision screwdriver in and very slightly bending the main rod out. I spent a while just moving it to the stall point, then looking at it for bind spots.  What I believe was happening was that the pin that holds the side rods onto the number 2 axle was colliding with the left-hand main rod. I've had it doing laps for about 15 minutes and no binds yet (some brief power loss once but that's likely my track).

Incidentally, I don't normally run it that fast, but when run at lower speeds it would bind after 1 or 2 clicks so to make the video I sped it up.

And yes, it was once per revolution. Much more accurate than the chuff rate in it's old decoder!

[Trainman203]

That's not surprising.....  clearances of running gear mechanical parts are a generalized problem  with the decapod.  I hope that the decapod gets reissued because I want 5 more at least.  Hopefully the mechanism will be improved.

[brokenrail]

Seems like the guy that commented on your video nailed the diag .

[Irbricksceo]

Seems like the guy that commented on your video nailed the diag .

how so? Unless I am misinterpreting what he said, he suggested the drivers being out of quarter, which they are not.

Edit: Is the poster of that comment one of you? The video was unlisted so I'm a but confused how a comment was made.

[brokenrail]

That deals with the side rods also.If it was not going so fast it would be more obvious to see.Steam kind of makes it easier to diagnose ,since you can see most of the mechanical parts involved,but not at the speed you were going .The comment was talking about taking steps to check things .That is how any diagnosis is done.Process of elimination.You have to know the right place to start to know what to eliminate in a certin order to get the correct answer.Test not guess!
Johnny

[Trainman203]

Well I'm glad you got it fixed Irbrick.    Those engines are very sightly, easy on the eyes.  It's too bad that they are plagued with issues that take time to figure out. 

I'll say again that  I'd like to see these engines come back one day with better mechanisms and with operation related CV's set better.... And , of course, with all the separately applied detailing that the serious modelers have come to love.