LOCO DERAILING.

[robert-1311322]

HI again,

 Didn t think I'd be posting again on the forum so soon,.so here's the issue I'm having. Having purchased the SCOTSMAN set I'm going about expanding the basic loop to cover what space i've got. you'll see from the pics ive expanded the basic oval shape to fit my layout shape. the train (the scotsman) runs fine apart from the left curve turn at which point it sometimes but quite often derails at the same point every time. I've checked that all the track is connected correctly which it is , i've also tried a combination of different size track  i.e half curves full curves etc, and even tried different size radius curves all seem to make no difference. All the track and points are Hornby the base board is flat and even at slow speeds the train still quite often derails at that left hand curve. At the moment I'm using radius 4 plus a straight piece to achieve trying to make the return again any help/advice gratefully appreciated.

 

 

 

 

 

 

Edited July 25 by RDS
To rotate the Pictures (hopefully!)

[What About The Bee]

Hi Robert

One observation is that you are transitioning from a right hand curve to a left hand curve.   Back to back opposite turns are a no no. There must be a sufficient length of straight between them.  Coupled wheels can be forced off track.  Similarly, the tender can drag the back of the locomotive off track.  You need to relax the right before going left.

Failing that:

One troubleshooting method is to slowly push your locomotive through the derailment zone, carefully observing the wheels.  This will show you the exact spot on the track, the exact axle, causing the issue.  

Bee 

 

[Going Spare]

As this concerns TT120, if the post were to be moved to that sub-forum there are more members there with experience of similar problems who can offer advice on causes & remedies.

[ColinB]

Not that I am an expert but weren't people reporting this as an issue with this model. I am sure I read articles about people playing with the front bogie. Before you do anything, remove the front bogie and see if it still derails. If it does then check back to back on the bogie and see if it is bouncing off the track.

[robert-1311322]

15 minutes ago, ColinB said:

Not that I am an expert but weren't people reporting this as an issue with this model. I am sure I read articles about people playing with the front bogie. Before you do anything, remove the front bogie and see if it still derails. If it does then check back to back on the bogie and see if it is bouncing off the track.

cheers colin i will try that.

[robert-1311322]

55 minutes ago, What About The Bee said:

Hi Robert

One observation is that you are transitioning from a right hand curve to a left hand curve.   Back to back opposite turns are a no no. There must be a sufficient length of straight between them.  Coupled wheels can be forced off track.  Similarly, the tender can drag the back of the locomotive off track.  You need to relax the right before going left.

Failing that:

One troubleshooting method is to slowly push your locomotive through the derailment zone, carefully observing the wheels.  This will show you the exact spot on the track, the exact axle, causing the issue.  

Bee 

 

thanks for reply bee, i will try a different approach with the track , see if that works. again thanks to all for replies, im away tommorrow, but will try give an update at some point over the weekend

 

[robert-1311322]

55 minutes ago, Going Spare said:

As this concerns TT120, if the post were to be moved to that sub-forum there are more members there with experience of similar problems who can offer advice on causes & remedies.

 thanks GOING SPARE,  but as im a bit clueless when it comes to talking/texting etc on forums, how do i in future make sure it goes in the sub forums that you are mentioning.

[atom3624]

If it's pulling the drivers off, I would check the pony truck wheels.

They don't 'horizontally float', and the pony doesn't move, but to keep those who like detail (me!!) happy, the wheels have to be as close to the track as possible - most times they're actually touching, with some 'vertical float'.  The wheels are crowned / rounded to help here as well.

Sometimes there's too much vertical float / slack and the insides catch the rails and ... pull the driving wheels off the rails .... this is where I'd check if you haven't already.  The retaining plate can be adjusted a little, to raise the wheels up perhaps 0.5mm - all that's normally needed.

Might be wrong.

Al.

[robert-1311322]

37 minutes ago, atom3624 said:

If it's pulling the drivers off, I would check the pony truck wheels.

They don't 'horizontally float', and the pony doesn't move, but to keep those who like detail (me!!) happy, the wheels have to be as close to the track as possible - most times they're actually touching, with some 'vertical float'.  The wheels are crowned / rounded to help here as well.

Sometimes there's too much vertical float / slack and the insides catch the rails and ... pull the driving wheels off the rails .... this is where I'd check if you haven't already.  The retaining plate can be adjusted a little, to raise the wheels up perhaps 0.5mm - all that's normally needed.

Might be wrong.

Al.

thanks atom, ive first tried BEE,S suggestion of changing the back to back opposite turns. it might be to early to say! but  so far it has gone round 15 times without one derailment even at a faster speed. still a big learning curve for me though this world, but i'm liking it.

[RDS]

@Robert, I am trying to rotate your images but the method I used very successfully on the previous Forum is not working.  I am still trying though!

[What About The Bee]

1 hour ago, RDS said:

 I am still trying though!

Attaboy!

[atom3624]

I just turned my laptop upside down!

Hope the trials work for the locomotive - should resolve all issues between the 2.

Al.

[Tim Allen]

This could be down to a few things, as previously stated it could be the loco. My Blink Bonny has gone back recently due to derailing and since returned seems to now be sorted. If the track has not been fastened down yet try going back to basics.

Set up the basic starter oval and run the loco to see if it derails, try each direction. Can you see if the front wheels are lifting, as this was one of the issues I had. If it derails constantly on the start up oval give Hornby Tech Support a call and have a chat with them. Double check the track is connected correctly, each rail at each join needs to be level and smooth. I usually run the pad of my finger across the top of the rail to make sure there's no stepping ie one rail is not in the fish plate (this caught me out a few times).

If it doesn't derail on the starter oval then it could be down to the track layout, as in the design. Model railway curves are unnaturally tight compared to actual rail curves so as others have said going from right to left might be causing it. Another thing to bear in mind is it might lift up elsewhere on the track and then finally derail on that curve. It might be worth watching it on the track prior to the derail curve. 

Finally the speed of these locos are not to scale, using a web converter I timed how long it took my Blink Bonny to move a set distance (990mm) and the scale speed worked out at 178MPH at full power. This means even at 50-60% power I was getting 80-90MPH scale speed. In real life if a loco took a tight curve at those speeds it would derail.

[Fishmanoz]

Mods, could you please move this to the TT:120 forum as it is a TT:120 loco.

Robert, once you find this in the TT:120 forum, check out the third sticky topic from the top of the forum where this problem and the fixes are explained in great detail.

[RB51]

Now in correct forum. R-

[Going Spare]

Thank you.

[Silver Fox 17]

On 25/07/2024 at 20:40, What About The Bee said:

One observation is that you are transitioning from a right hand curve to a left hand curve.   Back to back opposite turns are a no no.

I disagree totally.

I have put videos on in the early days showing forwards and reversing with 9 coaches without any derailment and that included 2 double slips as a reverse curve.

Someone (in 3mm ) also criticised the Peco curved points saying the inner curve was a no no and must have a straight before it. So, I placed 5 Peco curved points all in line in reverse curves and using the inner tightest radius went in both directions with stock without issue.

ALSO, don't forget putting an R6 on the curve of the point to turn parallel contradicts what you are saying so it is either the point with an issue or the loco. Also a crossover has a reverse curve contradicting your point.

Has you checked the bogie support arm for being exactly straight, then, do the guard irons foul the steps.

 

[Rallymatt]

I agree with Garry, Tim & Fishy the first port of call is checking the front bogie. The alignment, free running of axles and gauging are all important. Also check the detail is not fouling, steps and wheel irons on the leading edge of the bogie. 
Do consider cornering speeds too although if it’s due to any of above issues it will happen at very slow speeds. Models are capable of much higher speeds and tighter radius curves than the real thing. I do not think your track plan is the cause. 

[Brew Man]

But didn't the OP say he was hopeful that the problem was fixed using Bee's solution? Or at least he hoped it was fixed after 15 revolutions of the track. He's not been back so far to verify or refute.

[Kenneth-365689]

Looking at photo one, is the track pinned down or loose. Although you say everything is joined together probably have you checked to see if there is any 'bounce' in the track as the loco passes over it. Just a thought. 🤔

[What About The Bee]

My ego is not wrapped up in being right.  Let the data guide the outcome, not personality.

It is entirely possible on the 16th revolution, @robert-1311322's locomotive derailed.  He then performed other experiments or explored other options, like the front bogie.  Perhaps he tried the second suggestion I offered and found an entirely novel problem and solution. 

Perhaps not.

Much like the genuine, real life railways, there are sets of rules and recommendations.  Not following those rules can lead to speed restrictions¹.  Back to back opposite turns without an intermediate straight is a recommendation, not a strict rule.  Its your railway, rule #1. 

A few counterpoints to your statement @Silver Fox 17.  I hope that you see them as data points and not a personal attack.

Mention of the number of carriages, coaches of indeed any quantity of rolling stock is not germaine to a discussion about a locomotive that derails, when the tender does not.  While 9 coaches is an interesting figure of merit, it has little to do with Robert's problem.

Similarly, Robert's locomotive problem does not involve any point going into an R6 opposite curve, so as to get a parallel siding.  I do understand that you are conflating my back to back opposite turn recommendation, and accept that as a valid data point, yet it is entirely unhelpful to Robert in his circumstance. 

I would further suggest that ripping through that point, R6 configuration in real life, at maximum velocity, will result in equipment damage and engineman suspension for violation of speed restriction. 

Ask a real driver, @LesXRN. 

Layout Operators may wish to slow down through that configuration as well, remembering rule #1.  

Bee

¹  I have in mind a single track tunnel constructed a very long time ago, in which modern structure clearances were not prophesied.  There is a speed restriction in that tunnel, and even with that, the walls are constantly bashed.  This tunnel is a part of ancient US Railroad infrastructure and exists today.  Too much downtime, too expensive to fix.  Why not go to double track working anyway?

 

[Silver Fox 17]

All I am saying is you do not have to have a straight between the two parts of a reverse curve as stated by you and I have proved it.

[What About The Bee]

Correct @Silver Fox 17, no one is forcing you to do it.  You do not have to have it.  

Bee

[Kenneth-365689]

Take a close look at photo 1. The area where the strait joins the curve (about 1 locos length in front of the engine) looks to be in a valley with hills either side (yep, that's a bit of an exaggeration). Does the front bogie deraile as it passes that dip. 🤔. If so maybe a bit of packing under that area may be a short term solution. 

[What About The Bee]

23 minutes ago, Kenneth-365689 said:

Take a close look at photo 1.... Does the front bogie deraile as it passes that dip.

But the locomotive in image #4 does not show the front bogie derailed.  

Of the three coupled axles, front to back, numbered c1, c2 and c3; axle c1 is still on rail, whereas c2 and c3 are derailed.

Does a front bogie issue derail c2 and c3??? But not c1 nor the front bogie????  Does the front bogie re-rail itself???. That seems counter-intuitive to me. 

Bee