Catenary

 

NSW Railway Catenary  (one modeller’s experimentation)

A proposed line

One of the original proposals for a railway to Tumbarumba, was a connection off the Cootamundra-Tumut branch, with a line starting at Mount Horeb.  This line would go via Adelong, and be steeply graded.  The proposal suggested that such a line be electrified, with power coming from hydro-electric dams.

Of course, this option was dismissed, in favour of the line from Wagga Wagga.

I have debated if I should include an article on Catenary in my Buildingwagga blog, as the subject matter is not anything to do with the area that I am presently modelling   However, construction of Catenary  was part of my long modelling journey, and gave me confidence in pushing my modelling boundaries

 

Loftus station in 1994 - with a Tangara 8 car train

Why Catenary?

Whilst modelling catenary is not a requirement for modelling many railways, modelling catenary can be restrictive on prototype, location, or time period.  In this blogpost, I hope to demystify catenary, and provide a primer if you do wish to model it.

My own experience goes back many decades, when I travelled a lot on Sydney’s suburban network.  Whilst waiting for trains, I would often sketch  details of the overhead, and consider how best to reproduce it in model form.  Much of this was theory, until a few years ago, when I put theory to practice in installing the overhead on the ACT Model Railway Society’s Sydney prototype  exhibition layout “Yendys”.

 

Model Catenary

During the preliminary design stages for the ACT Model Railway Society’s exhibition layout “Yendys”, I wanted to install overhead over the mainline running tracks.  I knew that this would be a challenge, as at this time (2002), very little information, NSW catenary masts, or easily accessible reference sources existed.

Fortunately,  things were changing.  Train Hobby produced a series of books “Under the wires”,  ARHS NSW produced “46 Class Remembered” & “Sydney Electric Trains”, and more lately  by Bow River Publishing “The Leeds Forge Cars” & “End of an Era”.  All of these publications provide excellent photographic coverage, which both inspire, and instruct the construction of NSW pattern  catenary in model form.

We have also started seeing a number of models becoming available.  Whilst the Friedmont resin kit models date from the 1970s, the first RTR models from Bergs (Red Rattler 4 car set), and brass 46 class electric have spurred others.  To get some variety, one had a few kit makers. KeeWizz made the Tangara, the rare 86 class kit from Ian Lindsay Models, and the S set from Hanovale just opened the floodgates to some really high quality models.  Bergs continued with offering a 4 car UBoat set, a selection of parcel vans, double deck carriages, and a RTR S set.  Casula Hobbies had double deck cars. Southern Rail also had U boats, and a range of ready to place catenary. But it was Auscision that really pushed the variety.  The NSW 46 class, 85 class, 86 class, and VR L class for locos, interurban V class double deck passenger sets, the NSW Tangara, and VR Tait cars have been extremely well received, and most models are now sold-out. Wuiske models has provided catenary masts for Queensland, and I understand that a kit of the 3 car Brisbane Electrics was once available from them

A note about the terminology used.  I hope that I am descriptive with these notes, because I am not sure of the names used within the NSW Railways for the various part of the Catenary system

I trust that this primer, may encourage all to give catenary construction a go.

Where to start.

Before beginning,  I had a number of design decisions to make.

a)      What height the wire above the track

b)     What components will be used

c)      How does one connect module sections together

d)     Is the overhead to be made live

e)     Will pantographs be touching the wire whilst running

f)       What level of detail would be needed.

Given that the exhibition layout was going to take at least 3 years to build, I knew I would have some time to experiment. (in reality, the layout was started in 2004, and finally displayed in 2010)

Whilst I had some experience with model tramway overhead, catenary construction would pose a different set of challenges.  I read quite a number of articles in magazines (British and German), but the best guide was one produced by Sommerfeldt, which whilst they used their own components, covered a number of different prototype systems.

However, I also saw that the effect of Sommerfeldt, and other manufacturers overhead wire was one that looked chunky, and lacked the graceful, if near invisible nature of the prototype. 

As Sommerfeldt also made a number of “H” beam masts, similar to those used in Sydney, I  acquired a dozen masts for experimentation.  In addition, I bought  a large diameter roll of 300’ of 26 gauge phosphor bronze wire, and a Lima unmotored South African Blue train electric locomotive.

 

Gather information

A major step is to gather information:- plans, lots of photographs, and guidebooks.  For the Sydney catenary, we have been blessed with some great publications, which I have listed below.  Of course, I also had taken a lot of my own pictures.

Allawah in 1994. The new catenary masts had been installed on the platform, but the earlier masts style was still in use

Allawah again in 1999. New masts now in use.  The earlier brick buildings on the platform had now been replaced with steel and glass shelters.

Allawah in 2004. The main station had been upgraded with lifts for disabled access to the platforms. Note the way the catenary is squeezed under the building - and effect that I wanted for Yendys

Kembla Grange - simple modern style mast. Note the chain support for the arm, and the double contact wire.  The earlier NSW catenary only had one contact wire

Kembla Grange - showing the wire tensioning details

Single track mast - using a lot of chain supports

Another single track mast - the concrete base, and "H" beam is evident. 

 

 

Mast modification

The Sommerfeldt mast is correct for German prototype but apart from the actual mast, and concrete base, it looked nothing like the Sydney pattern.  So I removed everything german.  I then drilled holes for the contact wire pulloff, the support bracket, and the chain.

Bend up the support bracket wire, remembering to fit the insulator above the loop.  The chain can then be fitted, and the pulloff wire, suitably bent, with insulator.

The pictures below show this procedure with a Sommerfeldt German prototype mast

The test track –or- your first attempt at catenary.

 The first task was to construct a height jig.  I chose a contact wire height of 7cm above rail height.  NSW standards show that it is closer to 6.3cm, but by keeping the wire higher, it should be possible to fix the pantograph height of models at the right height, and still maintain a gap, to prevent pantographs from fouling, or getting caught in the wire. It might also be suitable for some of the larger USA models that club members may try to run.  (as a note, it is difficult to tell this ruse from normal viewing angles, and distances).  But I am getting ahead of myself. 

Taking a length of old track, I affixed a short length to some wood.  Holes were then drilled for the masts into the wood at a consistent distance from the track centreline.  The distance between masts was also around 40cm, this seemed to be a reasonable distance.   Without modifying the masts, I screwed them into the wood, and secured them with the supplied nut.

The first wire to be run is the catenary, or messenger wire, which forms the graceful curve typical of catenaries everywhere.  It fits in the upper loops of the supports off the masts.  This wire could possibly be correctly formed off the large diameter roll if one was good enough, but for my purposes, I weighted this wire down with wooden clothes pegs, which gave approximately the right shape.

The contact wire fits below the catenary wire.  Unfortunately, the slight curve of the wire from the roll is not ideal for this next step, and some method of straightening it would be desirable.  As my experiments were unsuccessful, I finally fixed one end to something solid, and kept  this wire under tension during the installation.  The results of my fudge worked to some extent, but I am the first who would say that this is not ideal.

(After I installed all the catenary on the layout with this method, I read of a method that used fine piano wire, and silver soldering for the contact wire.

I soldered a “L” shaped piece of phosphor bronze to the contact wire, and positioning the jig underneath at the right height, the top of the “L” shape droppers was soldered to the messenger wire.  Note, the “L” shape droppers extends above the messenger wire by some distance, as this allows height adjustment once the majority of the “L” shapes had been  soldered between the 2 main wires.   During installation on the club layout, I found that one could tack the “L” shapes in place at quite long distances, and come back later to install the extra “L” shapes in the spaces skipped or missed.

Once the contact wire had been soldered to all the “L” shape droppers, it is time to test the wire height with the jig, and locomotive if one has one.  Make any adjustments with the soldering iron, and once happy, trim off the excess length of the “L” shapes.

Take the Sommerfeldt german oattern mast (Left), and remove all the arms, leaving just a mast and concrete base

Fabricate new parts. The chain is fine twisted copper wire.  Add these to the mast, soldering the parts. Note you might have to drill out the existing hole in the Sommerfeldt mast

Continuing to make the contact wire pulloff.  The RHS picture shows the final result

I made a test bed with 3 masts (3rd mast out of picture).  Stringing the phosphor-bronze wire was to start with the catenary, bending as appropriate, and follow up with the contact wire which is soldered with droppers.  

4 track mast at Kogorah. The modern style has each contact wire supported with their own descender brackets

V set interurban approaches Springfield in the Blue Mountains. The older mast behind the newer mast has yet to be removed

Ballasting at Strathfield. The older catenary, and masts have more of a lacy look than the current style. Note the pulloffs are attached to wires only.  This is the effect I wanted for Yendys

Installation on the layout “Yendys”

Unfortunately, I did not take nearly enough photos of the Yendys during my catenary installation, so I will describe the process.

1)     After the benchwork had been built, the trackwork was surveyed for appropriate mast locations.  The jig constructed earlier gave a consistent distance from the track centreline, and the distance between masts was adjusted to fit the baseboard size, and to get around curves.  Occassionly, (as we used opengrid construction), we did not have enough width of plywood besides the track for the mast, so some extra plywood was added.

2)     All mast holes were drilled VERTICALLY.  This is most important.   The location of the holes was then marked, as the scenery has a habit of filling holes.  (Marking holes on the underside of the benchwork would have made finding the holes easier)

3)     Construction of the layout then continues in the normal fashion.

4)     Once trains are running, and the majority of scenery is in, relocate your catenary holes, and add the “naked” masts – i.e. after they have been stripped, and before drilling, or adding the NSW modifications.

A lot is going on here. The masts are in, and the contact wire is being installed under the catenary wire.  Note I have started from the #2 track - this would be harder if I had started with #1, or #3 tracks.  Modified Clothes pegs being used as a "third hand".  The height jig (block of timber) is visible.  The loco is a south African prototype (Lima) but an unpowered dummy

5)     Using the height gauge,  mark the height for the contact wire on the masts.  Remove the masts, relocate them to the workbench, drill holes, and modify them with the modifications as earlier described.

6)      Reinstall the masts, and then string the catenary wire.  I used clothes pegs to weight this wire between each mast section.  Careful tensioning caused the pegs to lift off the track, and this simulates the curve of the catenary wire between masts.  Kink the catenary wire at each mast, and solder the wire to the mast.

7)     Once the catenary wire is there, the contact wire should follow.  Make sure this is under tension, as we do not want it to sag.  Working your way along, solder the “L” shaped droppers onto the contact wire, and solder these to the catenary wire.  Keep checking with the height gauge, and fix any irregularities as you go.  Occassionly, I had to retension the catenary wire, by a mm or two, but generally this was not a major issue.  (The next picture shows this)

The contact wire is awaiting installation on track #3.  The subtle curve of the catenary wire can be appreciated from this angle

Another angle from the previous picture.  I haven't yet made a start on track #1

(Note that the L droppers extend above the catenary wires.  This is to allow modifications in the contact wire height above the track – either up or down.)

1)     Once the section had been wired, and adjustments made, it was time to move onto the next section.

Note.  The catenary section between masts acts like a girder – it can be bent side to side, but fairly rigid in the vertical plane.  This is a useful trick for the next point

2)     One of the extra challenges with an exhibition layout, is that each section, or module of the layout has to be separate for transportation, but able to be connected together.  My method was to utilise the ability of the phosphor bronze of the catenary to bend easily, but spring back to its original shape.  So by making one module edge rigid, the other modules catenary could be simply unhooked, and swung back and rested on part of the scenery (I used a lineside pole).  This allows the modules to be separated, keeps the loose wire secured, and also prevents losing the connecting wire.

The masts visible are on the bridge module.  The wire from the station module clips into this area, but is free to separate as needed.  Looks worse in the closeup, and unpainted

3)      Once all the wire had been installed, it was painted black, with a brush.  Black helps the wire “disappear” – in reality, Sydney’s overhead corrodes to a dark bluish-green colour

 

Cleaning the track.  One objection to stringing catenary is that the masts, and overhead wires will get in the way.  My advice, is to run trains frequently, and include a track cleaning pad under a number of wagons.  But, yes, sometimes you will need to physically clean, and your hand will impact the overhead.  The advantage of metal masts, and soldered phosphor-bronze, is that it takes a fair degree of force to break anything – the phosphor bronze wire by its very nature is springy.

My Hanovale model "S" set crosses the bridge over the flooded drain.  The join in the overhead between the modules can be just seen.

 

 

A big end note.  The overhead I have constructed for “Yendys” was not designed for continuous contact with pantographs.  Not only is it higher than the prototype, the joins between sections could snag the pantograph’s pan, causing damage, and derailments.  Also the pressure imparted by the pantograph would distort the wire, and over time, many of the solder joins could fail, both adding extra maintenance chores.   And I was learning as I went.  For instance, the first section that I installed was the bridge area, and I forgot the pull-off insulators.  I also stuffed up with the occasional “pull-off” direction, in that it was on the inside of the curve, not the outside.  Still, after around 130 hours of effort, the catenary was up, and certainly looks the part.

 

References

 

- Prototype Australian

46 Class Remembered                                     ARHS                                    ARHS NSW

The End of an Era                              Glenn Ryan                          Bow River Publishing

The Leed Forge Cars C3101-3150    R.Howarth/G.Ryan             Bow River Publishing

Locomotive Profile VR L & E class    John Sargent                       Train Hobby

Railway Electrification in Aust & NZ Geoffrey Churchman         IPL Books

Sydney Electric Trains                                      J.Beckhaus/S.Halgren   ARHS NSW

Under The Wires – NSW 85 & 86     John Sargent                       Train Hobby

Under The Wires – NSW Suburban  John Sargent                       Train Hobby

Under The Wires – NSW Interurban               John Sargent                       Train Hobby

 

- History

Electrification of Sydney and Suburban Railways                                      ARHS NSW

 

- Modelling

Catenary for Steam Railroad Electrifications   Noel Holley        NMRA 1994 Portland (Clinic Notes)

Overhead System Manual                Sommerfeldt                      Sommerfeldt

Traction Handbook for Model Railroads        Paul & Steven Mallery       2-10-4 Publications

               also

Occassional modelling articles in magazines rare

 

Modelling material (Australian suppliers)

Sommerfeldt                                     available from Orient Express and All-aboard Modellbahn

Wuiske Models                                  Queensland catenary masts – direct from Wuiske Models

Southern Rail                                     NSW catenary masts and portals – direct from Southern Rail (note – insulators are incorrect on their masts – they are for 25,000volt, not the 1500Volt Sydney system)

 

 

 

 

Postscript. Yendys has been exhibited for 10 years, and whilst I haven’t been involved for 9 of those years, I am pleased to say that the overhead still performs, and looks OK, despite the rigors of the exhibition scene.   

A bridge makes a convenient place to secure the catenary wires on firm non prototype supports between modules that cannot be seen from normal viewing angles

The flooded drain - inspired by the roadway on Bardwell Creek near Bexley Road after rain, was one was to limit the height of the modules for transportation. An empty river, or creek would not have allowed us to do this.  

However, advances in the hobby since 2010 been significant. and the latest innovation is to print your own masts.  Sometimes the hard design work has been done for you, and you can download the files for 3D printing for a small cost.  Whilst this link is for German, and Swedish masts, they point the way to what is coming , .

 

https://www.cgtrader.com/3d-models?keywords=catenary

 

Very fine catenary wire sections can be purchased from Sommerfeldt, or even Peco, that will save a lot of time, and frustration in trying to make your own – with some compromises in mast positioning, and cost to your pocket..

 

 

 

Until Next time