Large Scale Central

Heat expansion on Brass track

Track and Trestles
#21

Korm brought forth a very important point that many people miss, or it seems counter intuitive.

We have a number of concerns:

  1. visual: kinked track does not look good
  2. operational: bad kinks or track movement can cause derailments
  3. operational: rails pulling from joiners can cause derailments
  4. operational: rails pulling from joiners or excessive movement can cause electrical issues.

So, when the rails expand, they push against each other and grow in length. On curves the track moves outward, on straights the overall length will grow.

So you get track movement and kinks.

Now when the rails contract, the rails shrink, but the rail joiners do NOT “pull” the rail back into the joiner, usually you get gaps. There is no physical reason that the rails would be pulled back into the joiners.

Here’s where people get confused: when the rails expand again, they assume the rails will push into the joiners and take up the gaps.

NO, this does not happen. Why? Because there may be less resistance in the track moving, then trying to slide back into the joiner. Also, the gaps that were created are NOT distributed evenly, the gaps have to do with the resistance to movement at each location, some joiners will be tighter than others, some areas of ballast may have more resistance.

You REALLY complicate matters if you try to screw the ties to something in multiple places. Now you provide more places that forces cannot equalize. There is a reason that after years of experience, prototype track is STILL in ballast.

So, I lay my track without gaps on a warm day (just like railroads), and make sure I have some curves in long tangents. Works fine.

I have a friend that had concrete laid, LGB sectional track, and glued all the track to the concrete. Over time gaps developed and ties were ripped from the rails.

There has to be some give, just “gentle” securing of the track, and you cannot completely overcome gaps in all locations.

Greg

#22

Even with my track floating in ballast, I have to check the joints each spring, right after ice-out, for rails that have pulled out of the rail clamps. Then I run a locomotive slowly over the layout to detect any failed joints that my eyes have missed.

My first ship, a guided missile fast frigate (FFG) was designed without an expansion joint. Why, you ask? I dunno. Some landlubber at BUSHIPS thought it would be a good idea, I guess. Save some money.

Now, the expansion joints are necessary for two reasons. First, the temperature differential between the hull in the water, and the superstructure in the hot/cold air. Second, the torsion/compression the ship experiences as it alternately hangs bow and stern between two waves, or is suspended amidships over a single wave. (Shut up Rooster.)

Naturally, that always tended to cause the superstructure to fail, usually right at the Executive Officer’s Stateroom, just over his bunk. There are some things that even duct tape won’t fix. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-surprised.gif)(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-sealed.gif)(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

#23

My track also floats on/in ballast… My ballast is what they call ““aglime””, basically crushed limestone… When it gets wet, it dries like concrete… Need a hammer to break it up… Over the years, rail joints have separated due to heat and cold. When they did, I’d put in a SJ Expansion section of track… Joint failures/separations are less and less as the years go by…

#24

Well since my railroad is mostly curves, the curves move with temperature changes. The only joiners I regularly get gaps in are them plastic LGB insulating joiners, since they don’t clamp to the rails. Even them Aristo joiners stay relatively tight, probably because they are still in place on curves with staggered joints. As long as they work, I leave them alone.

The issue I deal with in the spring usually isn’t gaps at the joints. Its failed rail clamps or the old Aristo joiners. The Hillmann’s clamps are slowly breaking on me one by one, and occasionally, one of the old Aristo joiners fails. That has to do more with moisture freezing inside of them and breaking them, then it does with thermal movement.

#25

The SJ insulating joiners are much better than the LGB.

The Hillman clamps fracture more than the other brands, stress risers from the square slot.

Greg

#26

Greg, yes, I know, on both counts.

Thanks.

#27
Steve .  There are some things that even duct tape won't fix.      
Right but at least it will silence the noise they are creating!!!
#28

#29

Greg Elmassian said:

…There is no physical reason that the rails would be pulled back into the joiners.

…the gaps have to do with the resistance to movement at each location, some joiners will be tighter than others, some areas of ballast may have more resistance.

You REALLY complicate matters if you try to screw the ties to something in multiple places. Now you provide more places that forces cannot equalize.

yes, but…

i generally agree, but screwing/nailing down can make sense under certain circumstances.

being a chain smoker, i hate using airconditioning. the result is a train/hobby room with temperature variations of up to 25, sometimes 30°F.

that is enough for brass, to “work”, get kinky and pushed outside against the walls.

but, as i mentioned more than once, my layout consists mainly of one-foot pieces of track. so, when i lay track at about 80°F, i put a creditcard between railends.

then i nail down each section at one of its ends (3rd sleeper). - no kinks, no outward movement of curves. just expanding and contracting gaps. and, since the LGB-joiners can move only about 2mm against the sleeper webbing, the gaps stay more or less similar in size.

so, if the circumstances are: short pieces of track (many, but smaller gaps), LGB joiners, sideways fixing of sleepers - then it works out.

#30

Actually, I laid all my track, which is sectional, with a credit card gap. I’m no longer paranoid that I have to tighten the rail clamps until they bend, realizing that certain forces will overcome any rail clamp.r

So my situation is similar to yours, except SS rail and outdoors, otherwise pretty similar. I personally think the many joints give flexibility and minimize larger gaps.

Greg

#31

Greg Elmassian said:

…I’m no longer paranoid that I have to tighten the rail clamps until they bend…

Greg

Oh my! I never even tried to get them that tight. Something about working with copiers, printers, and cars for so many years, I am actually cautious about overtightening things.

#32

In the past I’ve subscribed to the torque specification “one turn past shear”, but I’m slowly learning (no I’m not, my old hands aren’t that strong any more). I’ve bent a bunch of SJ screws, but not so much lately.

#33

It hit 116 here today and right now at 6:45 its till 103. I have not checked my track yet but its 95% covered my a very thick shade tree and that helps a lot. It always moved some in the summer but the only way I can find the bad spots is to bring out the K-36, shes great for finding bad track.

#34

Daktah John said:

In the past I’ve subscribed to the torque specification “one turn past shear”, but I’m slowly learning (no I’m not, my old hands aren’t that strong any more). I’ve bent a bunch of SJ screws, but not so much lately.

Yea, since the Carpel Tunnel Syndrome, I don’t have as much power in my hands neither. The problem is, I don’t have as much feeling in my hands as I should. So some days I end up torquing things down a bit too much, because I cant feel how much I am torquing them down.

Bob Russell said:

It hit 116 here today and right now at 6:45 its till 103. I have not checked my track yet but its 95% covered my a very thick shade tree and that helps a lot. It always moved some in the summer but the only way I can find the bad spots is to bring out the K-36, shes great for finding bad track.

I have a passenger car like that. If that car runs fine for at least an hour, then everything should run fine too. Usually, she derails on the first goround if there is any track problem.

#35

Daktah John said:

In the past I’ve subscribed to the torque specification "one turn past shear.

My dad always said " don’t force it get a bigger wrench, if it breaks it needed replacing anyway".

When he was a teen he overhauled his first car and when they tried to start it it wouldn’t turn over, towing it did nothing but leave skid marks as rear wheels would not turn. Finally someone asked how he torqued the bearings, his reply was what do you mean torque them? H ahd just used a socket as tight as he could get them figuring they would fly out the block if they were not real tight

2 years later he was an avation mechanic in the Navy working on Pratt and Whitney 18 clyinder radial engines

#36

And 1:1 also deal with this issue as Dave Taylor recently posted on the sun kink on the Durango and Silverton Railroad

http://www.largescalecentral.com/forums/topic/19181/d-amp-rg-315-my-week-in-silverton?page=28

Jerry

#37

I have always had a problem with a large curve on the south end of the layout. It is in the sun all day. I have a double track layout and the distance between track centers is always changing. The thermal expansion and contraction can be as much as 1/4". My main problem has been Aristo Craft loco derailing on the curve because of the ridged truck frame. USA trains do not have that problem since the loco axles have individual springs. I have leveled the track and checked the center to center gauge, and the next day they both will have changed from the thermal expansion.

#38

Ron,

Have you tried ‘dead men’ under the ballast to maintain the track separation? Braces between them. Let both curves float as a unit.

John