What would users recommend as a sensible minimum curve radius?

[Audbr]

I have recently purchased a pre owned loco (R2937 GWR County of Cornwall) It works great on the layout at the Model Railway Society that I have recently joined. The next step is to build a small layout at home for the Grandchildren but I do not have a great deal of space. On the information leaflet that came with the ‘County of Cornwall’ it states ‘This locomotive should not be operated on track curves of less than 438 mm radius, which is Hornby second radius track’

 I then created a circular track using 8 pieces of R607 track (I.e second radius). The ‘County of Cornwall’ ran poorly with the front bogie constantly derailing. And the three main drive wheels did not look right when sat on the track. I replaced one of the R607 pieces with a point R8072 and a shorter length of 2^nd radius track. I had even more derailments.

 My conclusion is that the statement on the leaflet with the loco is incorrect and it cannot run reliably on 2^nd radius track. Has any body else had similar experience and what is the minimum practical radius that users would suggest I use?

 Interestingly I have some old ‘Triang series 3 second radius track’ from when I was a lad and the ‘County of Cornwall’ runs better on that than it does on new Nickle Silver track!! Conversely my old 1960s ‘Triang Princess Elizabeth’ runs better on new Nickle Silver Track’ than it does on ‘old series 3 track’. If I have to go to 3^rd radius track then the only points that have a greater curve than the second radius is the express points.

 For the Grandchildren I would prefer to build the track out of new Nickle Silver Track rather than try to use old series 3 steel track because with the newer track I get a better electrical connection between the track and the loco wheels

What would users recommend from practical experience as a sensible minimum radius for the ‘ County of Cornwall’?

[ellocoloco]

Hi Audbr

 

I would suggest using the largest radius you have space for! 

 

I am surprised that the loco is having problems with R2. (I am guessing that the MR Society you have joined has large sweeping curves.) As the model is s/h, you could check that the front bogie is free to move and 'sitting' correctly on the track. The service sheet should show if there is a spring to push it down on the track. It may be that there is an issue with the loco that doesn't manifest itself on larger radius curves.

 

However, you say it runs 'better' - does it still derail? -  on the Series 3 R2 track. I don't know if the S3 R2 is the same radius as the current S6 R2, but if so, is the new track laid flat? Uneven track can also lead to problems that your older Princess will probably handle because it will be heavier and have larger flanges on the wheels.

 

Best of luck, and let us know how you get on.

[Buz]

Hi Audbr

I was going to say 2nd radius curves as an absolute minimum, as many modern locomotives will not run on first radius curves.

It is also the minimum radius I work with on my tiny layout without problems other than the larger loco's I have looking silly.

My layout uses Peco set track and the club layout you ran on probably has nice sweeping curves with a large radius using Peco flex track.

I would suggest checking that the lead bogie pivots freely and that the back to back measurements are right on all wheels gauges are available for the back to back.

I would also make sure the track is flat and level particularly on curves and points, also make sure the points close properly and nothing is stuck in the flange ways and check rails or between the blade and stock rail.

Also check for stepped or badly connected track joints.

It sounds daft but also make sure part of the locomotive is not catching on any of the point operating system I got caught out by this one once and had to do some adjusting to the point operating system.

Because the County should run alright on second radius curves and points even at moderate speed, but don't let a child put it into Racing  gear 😆 even the best laid track and locomotives fail with that.

As the locomotive was second hand a good proper service would be a good idea.

regards John

[JeremiahBunyan]

Hi Audbr,

 

Like it's already been stated, since you bought the loco s/h, you may want to give it a thorough check. Most often than not sellers give you incorrect information when selling products. The seller could've bought a defective loco and tried selling it without listing the issue or damaged it and tried selling it without listing the issue.

 

Check your track to see if all the joints are fine? Check the front pony truck properly to see if it is sprung well and/or not missing anything.

 

You also said you made a circle out of 2nd radius curve to run it. I suggest adding a few straight sections to make the track and oval and also have a proper base to put the loco on the track. Setting your loco down on a curved section can result it in not sitting properly and thus derailing. Make sure nothing is fouling the front pony. If you can, take some detailed photos of the loco, especially the driving wheels and pony and post them, maybe someone can help?

 

I have a large Hornby LMS Duchess Class which is lengthy loco with a 4-6-2 arrangement and I actually tested it out on an oval of 2nd radius track laid out on my bed, yes my bed and it ran without derailing. So a smaller 4-6-0 loco constantly derailing can only be attributed to the track or an issue with the front pony.

 

I don't think it's incorrectly advertised, if bigger locos can go over 2nd radius curves, I'm sure a smaller 4-6-0 can.

 

Lastly, if you have space, try using 4th radius cruves and add some straights. Bigger locos are harder to place on a cruved section, especially when it's as tight as 2nd radius curves.

[atom3624]

From what I've seen of 'more modern' model locomotives so far, all of the above a valid comments and well founded.

 

The simplest response was also the most appropriate - use the largest radius possible.

Axles slided side-to-side, with articulated coupling rods as well, to permit tighter curves to be negotiated whilst maintaining all (apart from 9F's) driving wheels to be flanged.

 

Obviously as the curvature gets tighter / radius smaller, more lateral movement is required. Nice smooth articulation, with a 'little dab' of lubribation, and clean axles / bearings and coupling rods, etc, helps here.

 

Al.

[Mac-_-]

If you find that your track is ok. I would get a straight piece of track, put it on a flat smooth surface and put your loco on it, and check that the wheels are all in contact with the rails.

[Audbr]

Thanks to all for your comments. I have been out all day canoing with the grandchildren. I have only just got home and sat down with some red wine.

 The 'County of Corwall' runs well without derailing on old series 3 track but that is on a oval with series 2 bends and straights. 

Whilst the engine was bought 'pre-owned' it was in pristine condition the accessories in the plastic bags had never been opened. I suspect it had  been sat in the box somewhere for a while so I do not believe that the engine needs any servicing.

The track was a simple circle that I set up to check how my old Triang locos would run on new track. The track was set up on a thin board placed on top of a bed. 

I will do some further tests and respond in more detail over the next few days

Regards to all

[Chrissaf]

The track was set up on a thin board placed on top of a bed.

.

These modern multiwheel steamers need an absoutely flat rigid track.

[Ruffnut Thorston]

 @ atom3624

The simplest response was also the most appropriate - use the largest radius possible.

Axles slided side-to-side, with articulated coupling rods as well, to permit tighter curves to be negotiated whilst maintaining all (apart from 9F's) driving wheels to be flanged.

 

 

The original Tri-ang Hornby 9F, "Evening Star" was built to negotiate 1st Radius curves.  All the wheels that were meant to be flanged were flanged...

 

The real 9F locomotives also had the centre driving wheels without flanges.

 

This is one reason that no 9F locomotives are currently allowed to run on Network Rail, due to check rail, etc. clearances being changed since the class were last allowed to run on the national system. 

[atom3624]

Hi Sarah,

 

Thought I'd leave that one for somebody to pick up - real 9F centre drivers not flanged.

 

It does show just what a relative masterpiece the original Triang Hornby 9F was! I remember that 250mA load claim in the Hornby annual for the tender driven R/F motored locomotives.

 

Al.

[Ruffnut Thorston]

That's me....

 

I am a bit of a proof reader, and do tend to spot things.... 😀

[Mac-_-]

Audbr i get the feeling that space could be the problem, but as Chris pointed out above, the bed should be used for other pleasure's other than model railway's  😳. If you haven't take a look at the thread Track mat R8217, it's an eye opener to a small layout. An Geejbee as done wonders with the Hornby track mat, if you don't have one i'm sure it wouldn't be hard to get your hands on one.

 

Oh and keep it of the bed.  😮

[Audbr]

Just a quick update.

I removed the  fromt bogie gave the axles a bit of oil, slightly adjusted the spring and put it all back together.

The 'County of Cornwall' now appears to run around an oval track with radius  2 curves including a point.

It ruuns better (stays on the track better) running 'clockwise' than running 'anticlockwise'.  The first wheel to leave the track when a problem occurs is the front right bogie wheel when looking from the cab.

Is there any guidance anywhere on how to adjust the bogie spring for best performance?

Regards

Brian