# Why Steamer Front Trucks Derail at Turnouts



## MtRR75 (Nov 27, 2013)

Sorry, this is really long, but I believe that I have some useful info to share – and I have some questions about how to fix this problem.

First some disclaimers.

(1) I have been fiddling with model trains off and on (mostly off) for a number of years. Just starting to get serious in the last year. So I have some knowledge, but less than most in this hobby. What I do bring to the table are my skills as a scientist – my ability to analyze situations and design experiments to test theories as to what is happening.

(2) I now know why and how MY steamer front trucks are derailing at turnouts. I’m sure that there are other possible reasons for such derailments on other layouts.

(3) A brief explanation of my layout. I inherited a 4 x 8 layout from a friend who got it from the garage of his neighbor lady after her husband passed. The track is all Atlas code 100 and all brass. All of it is soldered together (except at block junctions). It is a double loop with a reversing diagonal in the center and a number of yard sidings. It has 12 Atlas Snap Switch turnouts on it. I have spend the last year rewiring the layout and building a new and better-designed control panel.

Now, on to the problem. First some observations.

(1) Almost all of the time when front truck derailing occurs, the loco is passing through the turnout by entering the curved track and merging onto the straight track. When the loco enters either of the straight ends of the turnout, derailment rarely occurs.

(2) Most freight cars pulled by my locos do not derail. Those few that do have issues of their own.

(3) Derailment usually occurs when the loco is leaving the turnout. The front truck derails just as it reaches the ends of the points. The wheel that is on the inside of the curve jumps on top of the rail briefly, then drops over to the other side of that rail. I will call that wheel the RIGHT wheel for simplicity (but left and right depends on which way your train is moving, and whether you are talking about a left or right turnout).

Now, HOW this happens.

(1) I had ordered an HO track inspection car from Micro Mark. It is basically a piece of clear plastic with two trucks attached to it. You can look through the plastic and see how where the wheels come off the track. I ran this car through the turnouts, but got no derailments – which was kind of expected, since my freight cars rarely derail.

(2) Then I removed the front truck from my 2-8-0 loco and attached it to the front end of the track inspection car with tiny amounts of tape – just enough to hold it on, but also allow it to pivot with the curved track. The front truck derailed, just as it did on the loco. I was able to move the track inspection car very slowly and watch exactly how the derailment occurred.

(3) As the front truck approaches the ends of the points, the LEFT wheel is on the point that is merging with the straight stock rail, while the RIGHT wheel is on the curved stock rail. On Atlas snap switches, the points are slightly shorter (vertically) than the stock rails (I know nothing about other turnouts). Therefore the bottom of the LEFT wheel (on the point) is slightly lower than the top of the straight stock rail that the point is merging with. Therefore, the side of the LEFT wheel (NOT the flange, but the fat part of the wheel), rubs against the side of the straight stock rail. Sometimes the left wheel will hop up onto the straight stock rail, and I get no derailment. But too often, the LEFT wheel stays down and thus pushes the RIGHT wheel up onto the top of the curved stock rail – and then over it – thus a derailment.

Other contributing factors and further observations

(1) By the time the front truck reaches the end of the points the loco’s driving wheels are on the point, and the weight of the loco appears to bend the points down more than freight cars would, but I did not test this. This may be one reason why freight cars are less likely to derail. Another factor may be that freight trucks have 4 wheels instead of 2 and this may somehow make them more likely to stay on track. But this is just speculation.

(2) These turnouts are old. The rivets at both ends of the stock rails are loose – some more loose than others. Loose rivets help make it easier for the weight of the loco to bend the points over, making derailment more likely.

(3) Adding weight to the front truck did not solve the problem. There is very little room for weight to be added to the loco’s front truck. But I did temporarily add 0.5 oz of weight to the front truck while it was attached to the track inspection car. This is far more weight than could ever be attached to the front truck when it is attached to the loco. However, the front truck still derailed.

Finally, my questions.

What can I do about this situation?

(1) Is it possible to tighten rivets on the snap switches? – without pulling up the track? – which is on cork roadbed. There is some ballast, but not enough and none on the switches. However, I’m not sure that this will solve the problem (see #2 below).

(2) Replacing the turnouts with newer Atlas Snap switches is a possibility --- BUT
(a) I really do not want to rip up all that soldered track. – AND
(b) I have a couple of newer nickel-silver snap switches. I set one up on a board in the same configuration that was causing the most problems. I ran the track inspection car with the attached loco front truck on that track – and it still derailed. There are some improvements in the newer switches. The points are tighter, but they are still lower than the stock rails.

(3) Any other suggestions.....

I really, really, really do not want to rip up the whole system and replace it with Peco (or any other) track. I would lose the year of work that I put into the new wiring and control panel, plus all of additional the time needed to lay the track – and I am not getting any younger. I want to finish repairing this layout and get on to the 5 x 12 L addition that I have planned. Also Peco does not appear to make a turnout with a turning radius as small as an Atlas Snap switch. If I have to convert to another type of track, with more gradual turnouts, I will lose the reversing diagonal in the layout – which I really like for operational reasons.

At my age, I need to take shortcuts somewhere if I want to finish this. My priorities (in no particular order) are: (1) steam era, (2) trains that run with out derailing, (3) DC operations – I like the mental challenge of operating several trains at once and keeping track of all of the blocks and turnouts, and (4) realistic vegetation scenery – that’s what I want to focus on when I get to the 5 x 12 ft addition – more scenery and less track.

If you made it to the end of this, thanks for your patience.


----------



## JNXT 7707 (May 5, 2013)

MtRR75 - 
I don't know how much I can help, other than to add some insight to your approach to solve the derailment issue and commiserate.
These mystery derailment problems are very hard to solve sometimes. Like you, I have literally observed the 'where and how' part, only to be stumped by the 'why' and of course how to fix it.
There are all sorts of seemingly insignificant variables that will conspire to take a certain set of wheels off the track. And maddeningly ONLY a particular set, and of course one which is important to you. 
Keep in mind too - pictures of your trackwork can be invaluable to those trying to visualize and help solve your problem..

Are the wheels of your loco in the proper gauge?
And I would ask - is the turnout perfectly flat (and in gauge as well?) , but you ran the test with the new turnout with the same results - which suggests the culprit is in the locomotive..
Do you have other steamers, and do they have problems on the switch?
Hos does your loco behave on other turnouts of the same configuration? 
Does it run OK in the opposite direction?

In my experience, snap switches in themselves are always a little problematic with their relatively sudden transition.


----------



## morrjr (Dec 20, 2012)

I had a similar problem, and it turned out the movable portion of the points was a hair out of gauge due to it being a bit bowed in the center. I carefully worked the tapered rail back into gauge, and no more problems. As the other poster said, check the gauge on the locomotive truck - it might be just enough off to ride up on the points.


----------



## DonR (Oct 18, 2012)

As I read your first post in this thread you have found
that the point rail head is a bit lower than the stock rail
head where your loco front truck derails.

My brother uses Atlas turnouts and has had derailing problems.
He found the same as you, a mismatch of rail head height
and solved it by using a clear plastic
shim under the the movable points. This raised the point rail
to match the height of the stock rail. Thus, no more derails.

I've found that in almost every instance of derails, the reason is
a height difference between rails that permits one wheel to climb the rail and
this includes ordinary flex track. 

Don


----------



## MtRR75 (Nov 27, 2013)

DonR said:


> My brother uses Atlas turnouts and has had derailing problems.
> He found the same as you, a mismatch of rail head height and solved it by using a clear plastic shim under the the movable points. This raised the point rail to match the height of the stock rail. Thus, no more derails.
> Don


I have gotten to the same point and am fiddling with shims under the points right now. But I have also discovered some other confounding factors. I will give a more detailed response, when I get it all sorted out.

Thanks go all for your input.


----------



## MtRR75 (Nov 27, 2013)

I have spent much time testing many combinations of locos, directions of travel, and different ideas to fix the problem. And for the moment, I seem to have succeeded in almost completely eliminating the derailments – using a combination of several things.

First -- to answer some of your questions:

(1) The front truck wheels are correctly spaced – according to my NMRA gauge.

(2) I have 10 (of my 12) turnouts (all identical older brass Atlas Snap Switches) with power to their track (still got to wire the other two). Of those 10, four have derailing issues (3 all of the time, and 1 some of the time). The other six are fine.

(2) The turnouts are NOT exactly in gauge. The rails are a little too far apart in the curved section. However, this is true for all 10 turnouts – and for the two newer, nickel-silver ones that are not installed on the layout. This seems to be a design flaw (or a design with a purpose that I am not aware of). At any rate, it is not the sole cause of the derailment – since the majority of the turnouts to do not cause derailments.

(3) I have 5 different steam locos: 2-8-0, 4-6-2, 2-6-0, 2-6-2, and 2-8-2. Three of them (2-8-0, 2-6-0, and 2-8-2) have front truck derailment issues – on the same 4 turnouts – and in exactly the same manner. The other two locos do not derail at any turnout.

(4) All derailments occur in only one of the three directions that a train can travel through a turnout. All derailments occur when the loco enters the curved portion of the turnout from the frog end and merges onto the straight section of track, and exits via the points end.

Now the solutions.

(1) The 2-8-0 loco was the only one that seemed to have a problem with the front truck itself. There is a bent flat spring that pushes down on the truck – presumably to keep it on the tracks. This spring is attached to the same spindle as the front truck. The spring and the front truck shift together from side to side as the loco moves into and out of curves. (They are held together by little bumps on the truck that the spring fits in between.).

The problem is that there is a flat-head screw where the spring rubs on the body of the loco as the truck pivots. There are abrupt edges at the top of the hole that the screw is recessed into. The spring catches on these edges, hindering the side-to-side movement. I tried sanding the area, with fine-grain paper, but the spring was still catching. So I put a small piece of a stick-on mailing label over the area where the spring travels. This solved that problem.

(2) I had noticed that the rivets that attach the ends of the points to the bar that moves them were loose. This allowed the points to lean over under the weight of the loco. I stuffed tiny pieces of card stock under the edges of the rivets to tighten them up.

(3) Following the suggestion of Don, I slid narrow pieces of plastic under the moving bar that the ends of the points are attached to. (I cut the plastic from packaging that lots of different items come in – the kind that it is hard to get into to get your tool or electronic gadget out of.) I found that 2 or 3 pieces was my limit. Any more caused the moving part of the turnout to bind. This raised the level of the points to almost the top of the stock rail.

(4) I used a small flat file to SLIGHTLY round the tiniest portion of the inside edge of the straight stock rail in the area where the point merges with it. This was more of an effort to remove any possible burr than to make the rail round. When I was done, I could just barely feel the difference. This was to make sure that the wheel was not catching on the edge of the rail instead of sliding onto it.

With all four of these things done, I have almost completely eliminated the derailments for all three locos. I have done this for 2 of the 4 problem turnouts. I still need to do the other two, but these were the worst two.

Next, I need to find a way to attach my card stock shims permanently to the moving ties in a way that does not restrict the slight rotation of the rivet when the turnout is switched. I am thinking about using some of those small fiber washers that KaDee sells (for adjusting coupler height) and slicing them open and wrapping them around the rivet.


----------



## DonR (Oct 18, 2012)

My sympathies are with you. Glad you've got some of the
kinks out. I went through the same sort of problems with
Atlas turnouts on my layout. I finally threw up my hands and
yanked 'em all. Replaced them with Peco Insulfrogs and the
derailing days were over. Peco builds quality products. You
see the difference instantly.

One problem with that. Peco turnouts have slightly different
track length diminsions. They will not directly replace an
Atlas. You have to do a bit of track realignments.

Don


----------



## rrgrassi (May 3, 2012)

Peco does not directly replace Peco either. I found that out when replacing #6 electro frog turnouts with #6 Peco Steamline Universal. The Steamlines were about two inches shorter (the straight part) than the electro frogs.


----------



## JNXT 7707 (May 5, 2013)

MTRR75 - I'll throw this possibility out there too: sometimes even though your wheelsets themselves are in perfect gauge, they aren't in gauge in respect with each other. By that I mean - one wheelset may be biased to the left of a truck with its partner biased to the right.
This will cause the truck to 'crab' down the track at a slight angle, and any imperfection will cause the lead wheelset to climb the rail ond derail the truck.


----------



## MtRR75 (Nov 27, 2013)

Your idea is one to keep in mind. But my problems so far have been with the 2-wheel trucks on the front of some of my steam locos. I used to have some cars that tended to derail, but with the improvements that I have made to the track and turnouts, those problems have gone away.


----------



## JNXT 7707 (May 5, 2013)

MtRR75 said:


> Your idea is one to keep in mind. But my problems so far have been with the 2-wheel trucks on the front of some of my steam locos. I used to have some cars that tended to derail, but with the improvements that I have made to the track and turnouts, those problems have gone away.


That is correct - it wouldn't be a solution for your 2-wheel truck issue but yes, something to keep in mind for the future. And an example of how subtle the variances are that can affect proper operation.


----------

