Expansion gaps

Looks like you are not getting an answer to this, the average situation is sort of right. The track has a design temperature at which the rails should be stress free, ie not in tension or compression. this will mean that the rails go into tension in the colder weather when the rail attempts to shrink and into compression in the summer when it tries to expand. This design temperature is usually above the mean temperature as the track structure can cope with tension more easily than compression.Tension is mostly contained by the tensile strength of the steel and the risk area is generally poor welds that may pull apart. Compression has to be constrained by the weight of the sleepers and the ballast shoulders preventing a buckle. This is the reason we sometimes get summer speed restrictions as any disturbance to the ballast from maintenance action or train dynamic forces makes a buckle, or 'sun kink' more likely. Note that new rail has to be welded in at the design temperature or lower as it can be hydraulically tensioned to the correct length but there is no way it can be shortened if too warm.

Keith Make friends in the hobby. Visit Garratt photos for the big steam lovers.

Reply to
Keith Norgrove
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Since many 1930s and 1950s coaches were roughly 60 feet long, the clickety-clacks with 60 foot rails would be almost synchronous.

I have re-wheeled all my rolling stock with the latest Hornby steel wheels, and find they make very little noise over rail joints, and not much more over points (where I have reduced the depth of the flangeway through the frogs with plasticard).

Reply to
MartinS

These are problems I have seen on several layouts. I apply the following rules:

1/ Attach wires to rails at the midpoint of the rail, NOT the ends. This is because the connection acts as a fixing point about which expansion will occur.

2/ Where a yard of rail is long enough to traverse the entire length of a board, ALWAYS cut the rail in half and lay with a gap in the fishplate joint. Wires are attached to rails as in (1) so that equal expansion is possible.

3/ NEVER solder rails to screws at the ends of boards: it creates a fixed point which means that rail expansion can only occur in the opposite direction across the entire length of the rail and create greate expansion on the far end of the rail than would occur if it was fixed at its mid point

4/ Don't use long lengths of rail - maximum 1M/yd

5/ When laying track, ALWAYS leave a small gap between rail ends - DON'T but the rail ends up together.

6/ ALWAYS use insulating fishplates or similar: simple gaps in rails can close up and cause all kinds of shorting problems, but don't rely on plastic fishplates as a means of maintaining track alignment - they don't have the strength.

7/ Never use breaks in rails at board joints as a means of separating electrical polarity (eg isolating sections, cross V's etc). It causes no end of confusion with wiring and when rails expand, the gaps close up and cause shorts.

Of course, these rules apply in environments where significant temperature variations occur. My layout was in storage for a year in a Sydney garage where temparatures could range from 0 degrees to 45-50 degrees. The above rules ensured that there were no expansion/buckling problems at all.

BTW: When prototypical CWR track is laid, it is tensioned up. Here in Sydney, I am only aware of one expansion joint on the Meadowbank viaduct across the river. Obviously, tensioning makes expansion joints largely unrequired.

Graham Plowman

Reply to
gppsoftware

I can well remember hearing the interrail gap/wheel interaction of a train on Southend Pier, horrendously loud!

Reply to
GbH

A rake of 57' coaches on 60' long rails is going to make a real cacophony of sound!

You should find the build-up of crud on the treads is much reduced too! :-)

Regards, Greg.P.

Reply to
Gregory Procter
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NEVER use insulating fishplates..........

Cut the rail with your Dremel tool, insert a small piece of suitable thickness of your favourite plastic sheet, add a touch of AC glue and when dry, file the plastic to the shape of the rail.

-- Cheers Roger T.

Home of the Great Eastern Railway

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Reply to
Roger T.

AC glue has little shear strength, particularly under tension.

Regards, Greg.P.

Reply to
Gregory Procter

"Gregory Procter" wrote

This shouldn't be an issue Greg - I always recommend cleaning all loco & stock wheels at the same time as your track. This may sound onerous, but in effect I find I only need to clean my track once or twice a year, and with all metal-wheeled stock, I don't have much of a dirt problem.

John.

Reply to
John Turner

"Roger T." wrote

We'll have to disagree on that score Roger. Providing you only use insulated fishplates on relatively straight track they shouldn't present any problem(s).

John.

Reply to
John Turner

In message , John Turner writes

One thing I discovered on my garden railway, is that Peco insulating fishplates (rail joiners) are pretty awful, because they are incapable of keeping the track in line. However, you've got to do something at an insulating joint. So this is what I have started to do.

Cut two three-inch-long pieces of rail. Join them with the aforementioned insulating fishplates, allowing zero expansion gap at all, then stick them to something to keep them in alignment (and curvature if necessary). Join them to the track with ordinary metal fishplates, allowing the usual expansion gap there, and carving the baseboard up if necessary to ensure all fits nice and level. A couple of

1/2" No. 6 CSK screws might help to keep everything in place.

The worst joint on my railway is between two points on a crossover, where the insulating fishplates have assumed a Z structure with about

2mm. difference in height between the tracks. Yes it needs fixing. No I couldn't be bothered at the moment. Next year, perhaps.
Reply to
John Sullivan

In message , John Turner writes

On my garden railway, it is a good idea to clean the track once a week, or even more frequently. Can I have some volunteers to clean the wheels of my rolling stock?

Reply to
John Sullivan

John,

One thing I am trying out in 7mm scale, where I want an insulated joint and alignment, is to solder a small strip of PCB across the undersides of the two rail ends with a gap cut in the insulation at the rail gap. I've actually used some gapped N scale sleepers which I had lying around from tracklaying many years ago and they seem to work well with sufficient strength to hold Code 125 bullhead in place. If I needed more strength I'd get some heftier PCB to do the job, although cutting that into thin strips might be a bit of a chore.

Jim..

Reply to
Jim Guthrie

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