Regrettable change …

Hi all,

Sorry for the delay in blog updates recently but I have been busy both on the layout and around the house.  There will be a few updates in quick succession.

After much thought and discussion with Andrew over the last nine months or so, we have decided to abandon Proto-87 wheel and track standards and to adopt the NMRA Fine:HO track and wheel standards.

Ever since we built Bowen Creek, we thought that diesel locomotive conversion was going to be straightforward – just a matter of swapping out the wheelsets.  However, during the few outings of the layout, we soon realised that some form of suspension was required to keep the wheels on the rails.  Since the P87 flange depth is only around 0.3mm, the slightest bump in the track or lack of lateral movement in the axles would cause the wheels to ride up over the railhead, most frequently on curves.  These issues, we found, relate mainly to three axle (Co-Co) bogies, and the centre axle in particular.

So, most of you may not be aware, but over the last three years or so, we had been developing a suspension system for retrofitting to RTR locomotives to enable the use of P87 wheelsets.

With greatly appreciated assistance from Andrew Lee of AndIan Models, we had designed an etched suspension ‘kit’ that would have replaced the pickup plates on the locos and incorporated sprung axle boxes.

Our initial testing, on the Trainorama 47 class bogies, proved the concept worked, but over time we realised that there were major reliability issues.  On the test track, the loco would run OK in one direction, but not the other, and derailing on curves was still an issue.

We both realised that whilst Proto-87 certainly looked nice, to get the suspension to work reliably on the locomotives was going to mean far too much work, and neither of us were prepared to further invest that amount of time and finances.  We both have layouts to build and quite substantial locomotive fleets to convert!!

Also, with the release of the new Auscision 45 class, it was noticed when I pulled a bogie apart, that the design of the pickup system is totally different to that of a Trainorama locomotive, which made the conversion to P87 almost impossible in my opinion.

So with heavy hearts, we are heading down the RP25/88 wheel route.  These wheelsets comply with the NMRA Fine:HO standards, and by keeping a track gauge of 16.5mm, we can achieve a flangeway of 1mm.  There is a requirement to open out the back-to-back of existing wheelsets to a minimum of 14.8mm.  Generally this is only about an increase of 0.2 to 0.3mm from factory wheelsets.  RP25/110 wheels will also still run through these frogs with a back-to-back adjustment.

Using the information in the NMRA standards S-3.1 and S-4.1, I have come up with a single page datasheet with all the relevant measurements shown.  Click on the image to open a larger PDF.

NMRA Fine:HO Standard

 

I have commissioned Keiran Ryan to design and manufacture some new etched vee crossings to suit code 70 rail with a 1mm flangeway in both 1:6 and 1:8 sizes.

I have recently received the first test etches of these and they are very nice.

With some minor corrections to be done, it is hoped I will have the production versions in a month or so which will allow me to continue on with the much delayed task of turnout building, along with changing out the thirty two vee crossings in the staging yards.

The images below show the two test etches for 1:6 and 1:8 vee crossings, the 1:8 crossing assembled and removed from its fret, and the 1:6 crossing installed in a section of track to test wheel operation.

P1010727

P1010726

P1010725

 

Cheers.

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Posted on August 17, 2015, in Miscellaneous, Trackwork and tagged , , , . Bookmark the permalink. 13 Comments.

  1. I’d appreciate it if you could give a bit more detail on the reasons for leaving Proto:87 and moving to Fine:HO.

    I have seen video of Andy Reichart running many P:87 passenger cars at high speed around a large oval track. I’ve seen that track up close in real life, and it is not a perfectly laid track by any stretch of the imagination. This is not a slur against Andy, who was a warm and generous host: he says himself that it was just laid down to enable experiments and demonstrations. Some of his work in the P:87 field is amazing. This demonstration made me think that P:87 was in reach of the average modeller, but the nagging question I have is about the locomotives and Proto:87.

    You’ll no doubt be aware of Greg Gamer making a similar decision: http://www.gregamer.com/index.php/tag/proto87/ He had trouble with a six-wheel locomotive with P:87 wheels running along a 24″ curved track. At first I thought the main cause might be that his radius was too small, however …

    Your blog post here talks of a similar problem: six-wheel locomotive with P:87 wheels running along a curved track. I’m curious to know what the radius of curvature was, and whether you think that the radius of curvature was the main cause, or if you think it was a number of other issues as well.

    Two years later, are you happy with Fine:HO?

    • Hi David, thanks for your comment. In a nutshell, we had major issues in getting the suspension to work reliably for 6 axle bogies. We had trialled our first attempts on 40″ radius curves and still had issues. We even had problems on near straight track, but are still unsure why. We would have had to invest serious money and more time into developing a suspension system to either retrofit to existing bogies, or to design a complete new bogie to then attach the sideframes to cosmetically. We just couldn’t justify that sort of commitment. To answer your question, yes I am happy with the move to Fine:HO. I can still construct nice looking turnouts with 1mm flangeways and all I have to do is adjust the axle back-to-back slightly. Cheers, Ian.

  2. Those crossing etches look like fun. I’d like to try a set. Are they available for sale?

    Chris

  3. Ian,

    I echo Rene’s reluctant understanding (Hi Rene) and feelings if loneliness!

    Good luck with the new approach and look forward to the end results.

    Julian

  4. Hi Ian,
    Good luck with the change. You and Andrew were the pioneers in Oz – Bowen creek was fantastic (Is it still operational). Have you ran the code 88 wheels through scale crossings, as I have some success with this when I couldn’t turn the wheels any further? Rene I’m sticking with you and Julian. Cheers Damian

    • Hi Damian,

      Bowen is part of Andrew’s home layout now, and will never be exhibited again. I think the problem with 88 wheels and scale crossings is the flangeway is too narrow and not deep enough.

      Cheers.

  5. Nick Sheridan

    Good decision. Any thoughts on the new SEM wheel profiles?

  6. Getting pretty lonely to be a P87 modeller!

    • Hi Rene,

      Yeah, it had come to the point where we just had to make the decision so we could move on.

      I wish you all the best with Pembroke, and will still follow with a keen interest.

      Cheers,

      Ian

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