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BLI 4-6-2 Derailing issue

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  • Member since
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  • From: Lancaster, NH
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BLI 4-6-2 Derailing issue
Posted by B Rutherford on Monday, June 13, 2022 6:38 PM

I have a BLI 4-6-2 that gives me almost constant derailing issues backing over turnouts.  The back set of drivers (so the first to reach the turnout) derail at least 50% of the time. This happens on various turnouts even when I am crawling over them.

Turnouts are all Peco code 83, track is Atlas code 83 flex.

These same turnouts don't give any trouble with cars. They also don't give any trouble with a Bachman 2-8-0 that I have, regardless of the speed I back over the turnout - including ridiculously fast.

I notice the BLI has traction tires on the set of drivers in question.  I am wondering if removing them would help?

I have two other steam locomotives due back from Tony's tomorrow (decoder install) so I plan to test with them as well.

What else should I be looking for?

Thanks!

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

  • Member since
    September 2004
  • From: Dearborn Station
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Posted by richhotrain on Monday, June 13, 2022 8:57 PM

Bill, I have a layout similar to yours. I use Atlas Code 83 flextrack and Peco Code 83 Insulfrogs. I use my finger to throw the spring loaded point rails on the turnouts. Among my steam locos, I have a BLI 4-6-2, and I have no problems backing up that loco over the turnouts.

From my experience with almost a dozen BLI steamers, when the driver wheels derail on turnouts, the rear truck on the engine is the problem. When backing up, of course, the rear truck on the engine reaches the turnout before the driver wheels. To avoid derailing, that rear truck needs to stay down on the rails to guide the approaching driver wheels. But, on a couple of my BLI steamers, tighter springs were needed to apply sufficient pressure. BLI fixed those issues for me. This could likely be the reason for your derailments when backing up the loco.

Rich

Alton Junction

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Posted by wrench567 on Tuesday, June 14, 2022 7:16 AM

  Hi Bill.

  Are you using the outermost hole on the drawbar? Is the harness from tender to locomotive dragging and catching the frog point when backing? Is it all or any turnout or just one?

 To be honest, I'm a max weight on drivers guy and remove the lead and trailing truck springs. After that if there is a problem with the lead and trailing trucks derailing, I add weight to the truck only. I also like to add weight to the locomotive too. But that is for pulling power.

     Pete.

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  • From: Vancouver Island, BC
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Posted by selector on Tuesday, June 14, 2022 12:23 PM

The two trucks on a steamer, if it has two, provide no guidance to the rest of the frame and superstructure. On the prototype, of course, but not on our models.  If anything, they're an impediment to good running on our scale locomotives.

I would be inspecting the traction tire to look at its condition. If it's worn beyond flush, or bunched, or twisted, or fractured due to aging of the material, chances are excellent that it hinders the passage of that axle around substantially curved tracks.

It could be that this one engine needs better care in how the turnout is engineered/made/laid. God knows how many times I have introduced a new steamer, and it also happens with new diesels (for me, anyway...) to my tracks and it won't get past a certain point.  All other locos I own run over that area without complaint.  So, I have to experiment and finally I get it work.  It's a sunken turnout center, or its humped....just enough that a flange skips or lifts and the rest we know. It could be as simple as one axle out of gauge. Or something is preventing that one axle from slipping sufficiently sideways to negotiate the curvature (it's called 'lateral motion'). It might be too curved, or some object or substance wound around the axle at the bearing is preventing slide in one direction.

Drawbars with too much friction or tension on them at the pin will cause the next driver set to also be running hard against the inner flange face of the outside rail. It can cause derailments.  Tethers has been mentioned.  Even a uncoupling hook on a coupler could be too low and snagging, although that won't be the case for a backing steamer, unless it's the preceding car that is the problem.

Also, it might not be attributable to just one of these.  Two or more might gang up on you and make the difference when their effect, in contribution, are summed.

  • Member since
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  • From: Lancaster, NH
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Posted by B Rutherford on Tuesday, June 14, 2022 2:25 PM

Rich,

Thank you - I hadn't considered reaching out to BLI for help but it is definitely something I will explore!

Pete,

It is multiple turnouts that are causing the issue.  I am using the outermost hole on the draw bar and the harness does not appear to be dragging.  Everything seems fine and next thing the back most driver is slighlty off the rail, always in the same direction (ie rear of train slips to the right)

Selector,

The traction tires definitely do not appear to be new!  Not sure how much wear is "acceptable" but these do look worn to me.  I have never dismantled a steamer at all, let alone enough to change traction tires.  Maybe this is something BLI could help with as well.  I have used various straight edges to check one of the turnouts in question and I don't find a hump or a dip.  The turnout is immediately after a curve and while I was careful to make sure the track isn't kinked I can't help but wonder if the curve has something to do with it.

I am anxious to get the other two steamers that are out for decoder install back so I have more to test with.

 

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

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    May 2014
  • From: Pennsylvania
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Posted by Trainman440 on Tuesday, June 14, 2022 2:32 PM

Hi, does the engine derail at slow speeds? What radius curve is the track right before the switch? What switch type is it? (#4, #6, 18" snap switch, etc)

The trailing truck spring might be too strong and lift up the rear section of the train enough to the point where there is less weight on the rear driver and therefore causing it be become more sensetive to track. Try removing the trailing truck spring (all you need are some screwdrivers) and see if the engine still derails. 
Make sure the wire harness isnt preventing the engine from turning properly. The wires BLI uses is rather stiff and sometimes might prevent the engine from turning. make sure no excess wires are in the way between the engine and tender. 

Does your engine come with a spare traction tireless wheel? If so it should come with a tool to remove the screws off the side of the wheels which hold the rods in place. If so, we can assist you in replacing the traction tire wheel with a traction tireless wheel and see if it still derails. Personally my guess is that the traction tires dont influence whether or not the engine will derail, but who knows. 

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the Santa Fe & Pennsylvania in HO

Youtube Channel: https://www.youtube.com/channel/UCLb3FRqukolAtnD1khrb6lQ

Instagram (where I share projects!): https://www.instagram.com/trainman440

  • Member since
    August 2010
  • From: Lancaster, NH
  • 96 posts
Posted by B Rutherford on Tuesday, June 14, 2022 6:09 PM

Charles,

It is a 30" radius into a peco #6 turnout.

Yes, it derails at slow speeds - sometimes a crawl last night but now tonight it required higher speeds to get it to derail - faster then I would normally run in reverse.

By hand the trailing truck seems to float easily, I can't imagine the spring is lifting the weight of the engine.

I will double check the wiring harness - no extra wires.

I bought the engine used with no spare parts in the box :(

I just did some more experimenting, the only time the issue shows is the diverging route. The engine gives ever the tinest hop along with an audbile click - again very slight as the back driver rides over the points.  I can't see anything that should be causing it - wondering if I should file the points a little to try to smooth it?  I should mention the switch is driven by a tortoise and appears to be making solid contact with the stock rail.

Also keep in mind this happens on other switches on the layout, just focusing on this one particular spot right now.

Thanks!!

 

 

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

  • Member since
    September 2004
  • From: Dearborn Station
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Posted by richhotrain on Tuesday, June 14, 2022 6:18 PM

B Rutherford

By hand the trailing truck seems to float easily, I can't imagine the spring is lifting the weight of the engine.

Nor can I, but my question is whether the spring is putting enough downward pressure on the rear truck to keep it solidly on the rails.

B Rutherford

 

I just did some more experimenting, the only time the issue shows is the diverging route. The engine gives ever the tinest hop along with an audbile click - again very slight as the back driver rides over the points.  I can't see anything that should be causing it - wondering if I should file the points a little to try to smooth it?  I should mention the switch is driven by a tortoise and appears to be making solid contact with the stock rail.

Also keep in mind this happens on other switches on the layout, just focusing on this one particular spot right now.

This doesn't sound like a turnout problem. I would not file the points. I am still fixated on the rear truck. What happens if you remove the rear truck?

Rich

Alton Junction

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Posted by selector on Tuesday, June 14, 2022 6:24 PM

Despite the lack of trouble with your other steamers, it doesn't follow that something is slighly 'wide' in variance from the NMRA specs for the matter, such as flange path clearances, rail gauge for the scale, etc.  Have you physically determined that you don't have a wobbly axle that is out of gauge when at bottom dead center?  Or have you checked that the gauge of the point-to-stock rail is correct all the way to the frog?  Sometimes a turnout's diverging rail, that would normally be slightly curved on the real thing and on hand-laid turnouts, is actually pretty much tangent rail.  This makes a difference partway along the way to the closure rail. While your other steamers seem to be indifferent, your problem is with this one Pacific. Somehow, with a nicely laid and well-supported turnout, one axle is climbing up and out of the gauge.  

Also, does the curve leading into the points run the other way, or do the points continue the same curve?  IOW, are we really dealing with an S-curve here?

  • Member since
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  • From: Lancaster, NH
  • 96 posts
Posted by B Rutherford on Tuesday, June 14, 2022 6:41 PM

Rich,

Charles had suggested maybe the spring was to strong, thus my last response.

I took the trailing truck off all together and still had the same issue.

I put the trailing truck back on and now the locomotive derails much more consistently.  I don't get it LOL  It now derails 8 out of 10 times but I cant for the life of me see why :)

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

  • Member since
    August 2010
  • From: Lancaster, NH
  • 96 posts
Posted by B Rutherford on Tuesday, June 14, 2022 6:47 PM

Wheels and points are both in gauge, just double checked.

Yes the points continue the curve.

I should point out that it is only the one driver that derails eventually dragging the next driver off with it. Trailing truck doesn't derail 99% of the time

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

  • Member since
    August 2010
  • From: Lancaster, NH
  • 96 posts
Posted by B Rutherford on Tuesday, June 14, 2022 6:57 PM

Selector,

What would be the best way to check for a wobbly axle?

Thanks!

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

  • Member since
    May 2014
  • From: Pennsylvania
  • 1,123 posts
Posted by Trainman440 on Tuesday, June 14, 2022 8:14 PM

richhotrain
B Rutherford

By hand the trailing truck seems to float easily, I can't imagine the spring is lifting the weight of the engine.

Nor can I, but my question is whether the spring is putting enough downward pressure on the rear truck to keep it solidly on the rails.

Rich

Yea that's what I meant.

-------

Okay so this is something really minor...but it COULD be a possibility. 

All BLI engines have fully sprung wheels. If the springs on the wheels are sprung unevenly, it would cause the first and last wheels to derail more easily. 

Imagine this: if the springs on the center driver were stiffer than the rest, and the springs on the first and last wheels were very soft, then the engine could have a see-saw effect of sorts, where either the front or rear driver has less pressure on the rails than the other. 

Say if this engine was front heavy, then the rear wheel would have less pressure placed onto the rail and cause it to lift easier.

Now we know BLI uses the same springs for all their drivers...BUT (i think) the center wheel is the one driven by the motor, and therefore has a gearbox. I do believe that wheel might be more rigid than the rest due to the gears resisting up and down motion.

Or even something as simple as the traction tires being thin and as a result making the wheel be just a smidge smaller than the others...idk all this could be reasons, however unlikely. 

Try placing something heavy (like a small bag of pennys, or just use your fingers) over the rear of the engine and see if it still derails. If it doesnt then it might confirm this to be the issue. 

This is of course assuming that your track work isnt the issue, and everything above was attempted and failed. 

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the Santa Fe & Pennsylvania in HO

Youtube Channel: https://www.youtube.com/channel/UCLb3FRqukolAtnD1khrb6lQ

Instagram (where I share projects!): https://www.instagram.com/trainman440

  • Member since
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  • From: Dearborn Station
  • 23,056 posts
Posted by richhotrain on Tuesday, June 14, 2022 10:41 PM

B Rutherford

I took the trailing truck off all together and still had the same issue.

I put the trailing truck back on and now the locomotive derails much more consistently.  I don't get it LOL  It now derails 8 out of 10 times but I cant for the life of me see why :) 

Yeah, that is weird. But, it makes that spring on the rear truck suspect. I was hoping that you would report back that the derailing stopped with the rear truck removed. That 4-6-2 only has three driver wheels on each rail, and a 30" radius curve should be easily handled with such a short driver set.

Rich

Alton Junction

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  • From: Dearborn Station
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Posted by richhotrain on Tuesday, June 14, 2022 10:44 PM

B Rutherford

I should point out that it is only the one driver that derails eventually dragging the next driver off with it. Trailing truck doesn't derail 99% of the time 

Yeah, that is usually how it works. The first driver wheel derails and the other driver wheels follow suit. What seems perplexing is that the trailing truck remains on the rails as the driver wheels derail. I just don't get that. I would expect the trailing truck to leave the rails first and then the driver wheels follow.

Rich

Alton Junction

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  • From: Dearborn Station
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Posted by richhotrain on Tuesday, June 14, 2022 10:46 PM

Trainman440

Try placing something heavy (like a small bag of pennys, or just use your fingers) over the rear of the engine and see if it still derails. If it doesnt then it might confirm this to be the issue. 

This is of course assuming that your track work isnt the issue, and everything above was attempted and failed. 

I like that idea. That would be a good test with and without the trailing truck on the engine.

Rich

Alton Junction

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  • From: Ludington, MI
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Posted by Water Level Route on Wednesday, June 15, 2022 6:05 AM

B Rutherford
Turnouts are all Peco code 83, track is Atlas code 83 flex.

My apologies if this has been mentioned, but have you checked the top of the rails to make sure they are perfectly flush?  I had a similar issue using Peco code 100 turnouts and Atlas code 100 flex.  The ties on the Peco were slightly thicker, making the rail slightly higher than the adjoining Atlas.  If so, the curve pushing the drivers against that incongruity could be allowing the driver to pick at the slightly higher lip of the rail enough to climb it.

Mike

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  • From: Dearborn Station
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Posted by richhotrain on Wednesday, June 15, 2022 7:15 AM

Water Level Route
 
B Rutherford
Turnouts are all Peco code 83, track is Atlas code 83 flex. 

My apologies if this has been mentioned, but have you checked the top of the rails to make sure they are perfectly flush?  I had a similar issue using Peco code 100 turnouts and Atlas code 100 flex.  The ties on the Peco were slightly thicker, making the rail slightly higher than the adjoining Atlas.  If so, the curve pushing the drivers against that incongruity could be allowing the driver to pick at the slightly higher lip of the rail enough to climb it. 

It is a good thought, but I would be surprised if that were the problem. I mentioned earlier in this thread that I also used Atlas Code 83 flextrack with Peco Code 83 Insulfrog turnouts without the issues that the OP describes. The height difference is very slight and does not seem to interfere with performance, forward or backward. The problem here seems to be in the wheelsets, either on the trailing truck or the drivers.

A 4-6-2 wheel configuration is not nearly as fussy as, say, a 4-8-2 or a 4-10-2, so my first inclination is to eliminate the driver wheels as the problem. Some years back, I did have similar problems when backing up a BLI 2-10-2 and a 2-10-4. I sent them in to BLI, and they installed stronger springs on the trailing trucks. Problem solved. That may or may not be the problem here.

Rich

Alton Junction

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Posted by John-NYBW on Wednesday, June 15, 2022 7:31 AM

I had noticed the same thing when attaching code 83 Atlas flex track to code 83 Peco turnout. I though it was because I had to pinch the part of the joiner that attaches to the Peco turnout to get it to fit snugly. To fix it, I bent that part of the joiner down slightly to get the rails flush. I hadn't thought of the possibility that the ties were different thicknesses.

I didn't have derailing issues because I tested the track running at very slow speed. What happened was the loco stopped because at slow speed it couldn't get over the raised rail. Had I first tested at normal speed, it might very well have derailed. Once I fixed that end of the turnout, I was having derailing issues with some cars when passing from the turnout onto the Atlas track and it looked like the track went down grade from the turnout. I thought it was because the turnout was right over a joint in the benchwork. I put a shim under the Atlas track and that seemed to fix the problem.

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Posted by B Rutherford on Wednesday, June 15, 2022 7:36 AM

Yes, top of rails are perfectly flush.  I use the atlas rail joiners which fit the Peco turnouts much looser then I would like resulting in me paying very specific attention to rail top flushness when soldering.

I will try the bag of pennys on the back of the loco. Won't be for a day or two as the next two days are really busy (can't wait until I retire lol)

The other thing I noticed last night is one of the pieces of connecting linkage on the drivers has a slight bend in it - not sure if it could be causing the issue, probably not but it does suggest to me that the engine has had a rougher then I would like. I am getting really close to sending the engine to BLI to see what they say.

I have two 2-8-2's due back today (one bachman, one BLI)  I am going to try them on the one turnout I have been playing with in an attempt to further eliminate a track issue.

 

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

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    May 2014
  • From: Pennsylvania
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Posted by Trainman440 on Wednesday, June 15, 2022 7:54 AM

Sending it into BLI won't help at all. They dont have your particular track plan so they wont be able to recreate the issue. 

A video of the derailing at different angles, and/or photos of the track would help too. 

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the Santa Fe & Pennsylvania in HO

Youtube Channel: https://www.youtube.com/channel/UCLb3FRqukolAtnD1khrb6lQ

Instagram (where I share projects!): https://www.instagram.com/trainman440

  • Member since
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  • From: Dearborn Station
  • 23,056 posts
Posted by richhotrain on Wednesday, June 15, 2022 8:03 AM

I wasn't actually suggesting that the loco be sent in to BLI. I was just relating my experience some years back. That said, however, if the problem is with the trailing truck when running backward, then the problem should occur with various track work setups. That raises another interesting point. If the OP has an Atlas Code 83 turnout around, he could swap out the Peco turnout and see if that solves the problem.

Rich

Alton Junction

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Posted by John-NYBW on Wednesday, June 15, 2022 10:56 AM

B Rutherford

Yes, top of rails are perfectly flush.  I use the atlas rail joiners which fit the Peco turnouts much looser then I would like resulting in me paying very specific attention to rail top flushness when soldering.

Even if the top of the rails are flush, you can create a hump if the track bends down too abruptly when the loco or rolling stock passes over the joint. It can create a vertical kink. I think that was my issue with rolling stock derailing after passing over the joint between the Peco turnout and the Atlas flex track. 

  • Member since
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Posted by B Rutherford on Wednesday, June 15, 2022 12:13 PM

Understood about the hump - I have used a 24" straight edge to check the track as best I can (because of the curve) and there is no hump evident.

Rich, I guess I misunderstood. The issue does occur at various points around the layout - always when backing over a switch, always the same issue.

Will be curious what the other two steamers show when I get them back which apparently won't be until tomorrow or Friday.  Also curious what the bag of pennies shows.  

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

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Posted by maxman on Wednesday, June 15, 2022 12:51 PM

Is this happening when backing through from the frog end or the point end, or either direction?

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Posted by B Rutherford on Thursday, June 16, 2022 6:56 PM

Issue happened when backing into the points.

I am going to declare this problem resolved...

I got my other two 2-8-2 steamers back (one a BLI and one a Bachman) and couldn't get either to derail over the turnout which led me to wonder if the troublesome engine was a good candiate to model a boiler explosion Smile

But, I decided to give it one final chance...  I kept running it back and forth over the track by hand and I could feel it binding a little at the points, in spite of the track gauge showing everything was good.  So I decided to file on the inside and top edge of the one point.  I figured if it didn't work I was going to replace the switch so I really had nothing to lose.  Long story short, it seems to have worked.  I backed through the turnout 15 or 20 consecutive times without a hicup, including way to fast.  Not sure if the filing corrected an issue with the turnout itself or my trackwork but I will take the win!  Fingers crossed the issue doesn't come back.

- Bill Rutherford Lancaster, NH

Central Vermont Railroad 

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    May 2014
  • From: Pennsylvania
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Posted by Trainman440 on Friday, June 17, 2022 8:50 AM

Ayeee! Glad it worked out! Yea I was really questioning if it was the engine that was the issue. More than likely, the switch needed a little bit of work to work right, I dont blame your track laying. 

Good stuff!

Charles

---------------------------------------------------------------------------------------------------------------

Modeling the Santa Fe & Pennsylvania in HO

Youtube Channel: https://www.youtube.com/channel/UCLb3FRqukolAtnD1khrb6lQ

Instagram (where I share projects!): https://www.instagram.com/trainman440

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