Derailment issues

[Pedro48]

Hi again everyone.

I am still having derailment issues on my layout. It is set out on a table 2.4 meters x 1.8 meters. I started out with a Flying Scotsman train set and initially used the track mat supplied to start my layout. I had derailments from the outset and eventually took off the front bogies of the loco, that helped.

I have since added to the layout and purchased more locos. The small Terrier can circumnavigate the entire layout without any issues. However, the larger locos ( Flying Scotsman, Mallard & Cock O the North) all have derailment issues.

The points I am using are R8072 & R8073 as supplied in the extension packs. I have come to the conclusion that the angle (22.5 degrees) is too tight for the larger locos with bogies. I am considering changing to the Express Points (R8077 & R8078) as the angle is much less (11.25 degrees).

Will this solve my derailment problems, an expensive exercise if it doesn't work as these cost around $55 each in Australia and I have 8 points in my layout.

Any advice would be appreciated.

[Gordonvale]

@Pedro48

If your conclusion "that the angle (22.5 degrees) is too tight for the larger locos with bogies" was correct, the whole world of Hornby would be derailed.

My layout contains 100+ R8072s & R8073s and I don't have derailment issues. The track is securely pinned to a level baseboard, thereby preventing track movement when forces of gravity are applied to it by moving locos.

Hope this helps.

[What About The Bee]

Hello Pedro48

Change for the sake of change will not solve a problem. It may help you to find the root cause, but stumbling upon the solution to the root cause rarely occurs this way.

Slow down.

Exactly how does your locomotive derail? Slowly push the locomotive through a troublesome point. Do the wheels snag on the point rails? Pinch on the check rails? Drop into the frog? Do the wheels pick the point? What happens? Where is the problem? Precisely.

You mentioned that removing the bogies helped, but you still have issues. This is a perfect example of not finding root cause. You made a change, but really didn't solve the issue. Put those bogies back on. Check all your wheel geometry, but in particular, the back to back of every axle.

Before another change, find the issue. That way, when you do change a parameter, you know it attacks the root cause.

Bee

[Pedro48]

Thank you Gordonvale.

I have used a spirit level and straight edge to ensure that the track is level and there are no twists in the track or points. I have adjusted all B2B to be 14.4 mm.

The locos can go straight through the points okay, it is when it exits or enters left or right that the problem occurs, from any direction entering the points.

I moved a loco by hand slowly into the point, the wheels appear to jump when they hit the plastic section of the intersection.

Very frustrating.

[What About The Bee]

Hi Pedro

Thank you for clarifying. By "when the wheels hit the plastic section" do you mean the plastic check rails or the plastic frog?

I hesitate to add a picture, or we will have to wait for a mod.

If the wheels jump UP, then some causes may be:

1) the wheel flanges are hitting the bottom of the frog. The solution is to simply remove a tiny bit of material from the bottom of the frog where the wheel flanges go, the flangeway.

You say that the wheels jump "in any direction" of travel, so this is more likely. Contradicting this is your statement that the locomotives roll through straight without issues. The depth of the flangeway in the frog will be the same for diverting and non diverting routes. If the loco can roll through non diverting without jumping, then the flangeway depth is likely not the issue.

2) the wheel is hitting the point of the frog, right where the rails come together. Picking the point. Although 14.4 mm B2B is to the specification, you can be at 14.35mm and still be in spec. The controlling spec is the width between check rails, at 14.1 mm +/- 0.1mm. Your B2B must clear this. Setting the B2B at 14.3mm or 14.25 will tighten you up around the check rails, pulling the wheel from the frog point.

As you mention the wheels jump from any direction, you are not likely to be picking the point (2).

Along these lines, would you mind describing how you are setting your back to back? Calipers? Tool? Guage blocks?

3) there is a bit of something in the gap between the check rails and the stock rails. When the wheel hits it, it jumps. Consistent with "any direction". Check with some plastic card stock. Make sure they are clear. Unlikely to be on multiple points, but...

4) All rails at the same height? I know this seems to obvious, but worth checking. Run your finger over the top of the rails, check to see its smooth.

If the wheel drops DOWN then jumps up, at the frog: This means that the drum of the wheel, at the frog, is rolling off the rail and then "dropping in" to the gap. The wheel lands on its flange and rolls forward. Naturally, the wheel will jump up when it meets the rail again.

Have you checked your points to see that they are meeting specification?

Bee

[Fishmanoz]

Not the solution as indicated by others but $55 for express points sounds very expensive. Are you sourcing in Oz, via Hornby site or via other online like Hattons?

[ModelerXYZ]

Move a loco very slowly through the points and watch it. It is posible that the flangeway is not deep enough- file it out with a small file. See if it happens again.

The fact that the terrier with smaller wheels can get through indicates that the problem is the bigger wheels on the locos, not the small ones on the terrier. This is consistant with what I say about the flangeway not being deep enough.

XYZ

[Pedro48]

Thank you all for your input.

The wheels jump when they hit the frog. I dismantled the 2nd radius where I am having the problem, I then reassembled the track, swapping points around. I have 2 right hand points connecting the 2nd and 3rd radius, The Mallard (only one I am running at present) only gets half way through the junction when it jumps off the track.

I have checked that the table is flat and level and that the track and points are also level, it is smooth when I run my fingers over the joints.

I can run the Mallard slowly in reverse and seems okay although the bogies wobble when passing the frog.

I don't know why this is happening now, it running okay except the past couple of months.

I can run the Mallard and Cock O the North on the outside radius without any problem, there are 3 points on this section and there are no problems with them.

Peter

[Pedro48]

I have had some success at last. Using a Vernier Caliper I set the B2B on the bogies to 14.3 mm, it still wobbles slightly but it is not derailing, all other B2B are at 14.4 mm.

The Mallard can now traverse from the 3rd radius to the 2nd radius very slowly, but at least it is an improvement.

I thought that model railway would be a relaxing pastime in my retirement, not always the case.

Thank you all and I will still play around trying to improve the running.