# Expansion joint



## Wang Shaolin (Mar 4, 2014)

Where is expansion joints use ? Describe with some examples ?


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## chuck n (Jan 2, 2008)

Most of us do not use expansion joints. If you float your track on ballast, it will expand and contract with temperature. If you look carefully you might see a shift in your curves over the course of a year. 

If you have a platform or some other structure under your track do not put your anchoring points too close together. One anchor every 4-6 feet should be sufficient.

If the anchors are too close together you will run the risk of your rails separating from the ties. I knew a guy in Denver who anchored his track about every foot. One hot day he came out and discovered that his ties were still in place, but the rails were loose.

Minimal anchoring is best.
Chuck


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## East Broad Top (Dec 29, 2007)

They're helpful when you've got very long stretches of straight track (on the order of 50 - 100' or more). The Denver GRS uses them on their club layout at the Colorado RR Museum. On curves, as the rail expands, the curve just pushes outwards a bit (increasing the effective radius of the curve). On straights, there's no natural direction for the track to go, so without something to compensate for the expansion, the straight track starts to "S" back and forth. Expansion joints allow the rails to move a bit, avoiding the "S" problems. 

If your track is fairly frequently anchored to a subroadbed to where it can't shift one way or another, the expansion joints are helpful because otherwise you may find the rails popping out of the ties. 

Later,

K


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## backyardRR (Aug 14, 2012)

I use Aristo Craft track with the supplied hex screws joining the sections.
For expansion I have simply left the screws out at about 4 places
around the 90' loop. To maintain electrical connectivity I have soldered jumpers around these joints. Oh, and the roadbed is the "floating" method.

Wayne


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## East Broad Top (Dec 29, 2007)

One caveat to just letting rail joiners slide on the rails; you've got to periodically clean the ballast dust out of the joiners so the rail can close the gap in the joiner as it expands. Otherwise it just gets more and more dust in there as the rail contracts, and it can't expand into the joiner again. When I haven't been terribly attentive to this (and especially when rain or watering splashes a larger chunk of ballast into the joint), I've had gaps of 1/4" or more that wouldn't close back up. 

Go out on a cooler day when the gaps are on the wider side of things with a jeweler's screwdriver and a can of compressed air. Stir the dust in the joiner with the tip of the screwdriver to loosen it up, then blast it out with the air. This isn't something you have to do regularly; I do it probably once a year on joints that look wide. 

Later,

K


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## Semper Vaporo (Jan 2, 2008)

My elevated track was a double-loop back to a 50-ft mainline between them. I had the track loosely tied down with fishing line under one rail, over a couple of ties and under the other rail, with the ends tied together under the wood structure (I feared a strong wind blowing the track off). I used just the little rolled metal spring clips to join the rail ends and dutifully put a dime in each gap when assembling the track.

When it got hot, the gaps all closed up and the track continued to expand slightly causing the loopback to increase noticeably in diameter (straining the fishing line!).

When it cooled down again, the gaps did NOT open up uniformly. Instead, the diameter of the loop backs got noticeably smaller until the track began to catch on imperfections in the wood elevated structure and the ONE gap with the weakest grip on the rail ends released the rail and the gap increased in width by the sum of all the gaps that had closed up, resulting in a gap wide enough for the rail to come completely out of the clip.

When I first built my track, I always got my Aster Mike out, fueled and watered it, did the traditional "oiling around" and then put a boxcar on the track and manually walked it around the track to inspect it while the engine built up steam. I never found a problem other than an occasional twig or acorn that needed removed. One day when I went out to play I was tired and feeling lazy and since I had never seen a problem with the track itself, I just visually looked around at the track to see if there were any debris that needed to be removed. Not seeing anything, I connected the train to the engine and started out around the loopback. THAT WAS THE DAY THAT THE TRACK GAP HAD COME APART! Dumped my Aster Mikado 3-ft to the ground!

I removed all the fishing line tying the track down and added lots of ballast to let the track completely float. The track never blew off the structure, even in severe Iowa Spring storms. Some of the track joints I needed to tie together with fishing line wrapped around a few ties on each side of the joint to keep them from coming apart again! In the temperature extremes from sub-zero in the winter to unbearable sunshine heating the track in the summer, the 17-ft. diameter loopbacks varied in diameter by close to an inch or two.

Based on my experience, I strongly recommend that you don't "nail your track down"... I do recognize that there might be some places where it is necessary, such as next to a loading-dock or over a narrow bridge where movement might cause clearance issues; then expansion joints are used to mitigate the problems with thermal expansion, otherwise, let it float.


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## Totalwrecker (Feb 26, 2009)

Welcome Wang,
It seems we have a variety of way to deal with expansion. 
Before suggesting a way good for you, I'd like to know a little about your track plan.

Only if you plan long straight a ways and have large seasonal temperature changes and your track is in the sun would you need the expansion section of track. However if your plan has more curves and shorter tangents (straight sections) then your expansion will be more lateral than linear.
My experience is in Southern Arizona, in open sun. Aristo Stainless steel and all tightly screwed or clamped together, free floating in native broken rock. I let the whole layout expand and contract. I never let the joints open, there is no guarantee they will close up, specially when grit gets in the joiner. 
I have witnessed lateral movement on a 90 degree curved trestle. I had built it with 3 stringers on top to allow the track to move and be supported. It 'grew' about 1/2 inch to the side, in the middle of the curve. Each tangent had pushed it out some.

For some a track saver, for others just an added expense. Your mileage may vary.
Happy Rails!

John


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## Wang Shaolin (Mar 4, 2014)

Totalwrecker said:


> Welcome Wang,
> It seems we have a variety of way to deal with expansion.
> Before suggesting a way good for you, I'd like to know a little about your track plan.
> 
> ...


Thanks for giving your suggestion. Actually i am learning about expansion joints. So i want to clear on fundamental of Expansion joints.


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## Trains (Jan 2, 2008)

I use expansion joints on my layout, it is on PVC plastic ladder and it expands different then the track. I have three, I put them on the longest straight tracks.

Don


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## Wang Shaolin (Mar 4, 2014)

Trains said:


> I use expansion joints on my layout, it is on PVC plastic ladder and it expands different then the track. I have three, I put them on the longest straight tracks.
> 
> Don


Thank you so much Trains, Is that PVC plastic ladder is stronger than a steel rod ?


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## Totalwrecker (Feb 26, 2009)

Wang,
I doubt if it is as strong, but that depends on the stresses applied.. 
The ladder system is surprisingly strong, but as Don noted the plastic ladder stretches faster than the track, so it might pull on the track, if it can't expand or stretch then the track path around the closest curve would likely be altered... not a good thing.

There are several threads in the forums that explain how they work.

It would be helpful if we know your conditions. Rather than explaining every way, we can make suggestions you can use!

Happy Rails

John


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## Trains (Jan 2, 2008)

My PVC has been out for about five year with no problems. I'm sure it's not stronger then steel.
I have my risers two apart, and had a USA Trains Big Boy running on the layout.

Don


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