G Scale Model Train Forum banner

1 - 20 of 20 Posts

·
Premium Member
Joined
·
658 Posts
Discussion Starter · #1 ·
I have aluminum rail with expansion joints. The problem is that the expanding rail will not slip in the ties. How do you set up the rail so that expansion joints work?
 

·
Premium Member
Joined
·
687 Posts
Bill

I too have aluminum rail - code 215 Llagas Creek well known for the tight tie to rail fit.

My track is firmly fastened to a hard roadbed either pt 2x6 or a ladder made of TREX. Expansion joints are left at the end of each flextrack section. I spike every 12th tie or sometimes a bit more frequent if needed, with an aluminum nail to hold the track to the roadbed. The tendency for most modelers is to spike the tie with one nail in the middle but this leads to twisted ties as the rail expands because it will not slide through the ties without binding. I spke the ties with two nails through the tie ends outside the rail and leave the head slightly proud in case the track has to be lifted.

I have had no problems with heat expansion.

Regards ... Doug
 

·
Premium Member
Joined
·
937 Posts
Hmmm...good question. Since I live in Northern Kansas where it will be below 0 in the winter and above 100 in the summer I too will have to deal with track moving all over the place. Smart idea to put 2 nails in each tie, that makes alot of sense.
 

·
Premium Member
Joined
·
6,187 Posts
The problem is that the expanding rail will not slip in the ties

Bill,

That's the argument for 'floating' track. My layout had Llagas aluminum code 250 rail with s/s rail joiners placed on a flat ballast of crushed rock. It wasn't fastened down at all, except by the action of the ballast. It stayed roughly in place and never gave me a problem - and we go from 0 to 100 degrees here too.
 

·
Registered
Joined
·
518 Posts
Anyone who has walked along a railroad in hot weather will know how hot the track area can be. Some degrees hotter than the surrounding area.
To a smaller degree the same holds for a model railroad which is well ballasted.

Just another slant on a well trodden thread. /DesktopModules/NTForums/themes/mls/emoticons/laugh.gif
 

·
Premium Member
Joined
·
5,510 Posts
I have Llagas Creek code 215 Nickle-silver track. I used the plain slip-on rail joiners. When I assembled the track, I put a penny or dime between the rail ends as a gauge to allow for expansion.

When the track heats up and the rails get longer due to expansion of the metal, the small space dissappears, as was intended.

Unfortunately, when the track then cools down and the rails contract, the one rail joiner with the least resistance to slipping is the only place that opens up. Thus all the places where I have joiners, only one creates a gap and it is now the sum of all those dime/penny thickness gaps I stated with.

To be done right (at least as far as controlling expansion joints) each rail needs to be solidly affixed to some sort of underlayment ONLY at the very center of the length of the rail. Thus expansion and contraction would only be allowed from the center to the end and the whole length of rail could not be pulled toward one end. The expansion joints would have to be designed to handle the absolute maximum and minimum length the rail might reach. Of course, the underlayment may have some expansion/contraction coeffiecient to contend with too.

I am now of the opinion that there should be no expansion joints except in very rare and special cases. The whole track should just float completely such that loops or circles, in total, get bigger or smaller in diameter, which is what happens on my track now anyway. Unfortunately, after mine expands, upon contracting again, something will catch and keep the circle from reducing in diameter and one joint somewhere around the loop will come apart.
 

·
Super Modulator
Joined
·
21,053 Posts
Bill, you did not state the manufacturer of the rail you are using.

I've been doing a little talking and a lot of listening on this subject recently. Also, with the convention in Phoenix, you got to see the layouts and talk to the owners of probably the toughest place in the US, it gets very hot, and also very cold there.

Two basic methods:

Free floating track, or screwed down.

If you free float the track, I think it's best to let the entire track section expand and contract, rail and ties. You will eventually get some movement in the ballast, as the ballast tends to lock the ties in place, but the expansion and contraction is irristable. Some people use sections of expanding track, like the Hillman or Split Jaw stuff. I am talking of the short sections of track where the rails slide against each other. Dion't even think about "expanding rail clamps". The most frequent use of these sections was every 20 feet!.

If you really want to screw down your track, i.e. the ties, then it seems best to let the rails slide within the ties. This may not be possible on all types of track. On Aristo track, the "spikes" are VERY loose, and all you need to do is remove the small screws underneath. On some other track, it's really too tight to do this. You really need to have expansion joints, and I would still use expansion track sections and rail clamps. If you don't then you should have loose joiners, i.e. forget track power, because all the track will not "nicely" distribute those gaps you left between rail sections, they WILL all bunch up, and if you have tight joiners, you will still have trouble.

This is the best info I have, and so far, have not seen any layouts where these things are not really true, just have to "dig" sometimes to really understand what is happening, sometimes it not obvious, even to the layout owner!

Regards, Greg
 

·
Premium Member
Joined
·
658 Posts
Discussion Starter · #8 ·
It's Micro Engineering rail and ties. The problem seems to be that the rail expands but the ties don't. When this happens, the ties cock slightly and the rail can't move. The track is all free floating on cement roadbed.
 

·
Premium Member
Joined
·
301 Posts
Here's a graphic illustration of the effects of track expansion.





This is an overview of Ken Molchanow's RGS South Jersey Division in (where else?) South Jersey where we were having an operating session last summer. Ken has built this beautiful layout with Llagas Creek code 215 aluminum rail which "floats" on a foam roadbed - IOW, it's not secured to the underlaying base except at the switches. Notice the double passing sidings in the left foreground.





By the end of the day, the temperature had topped 100° F. Since the middle track is "pinned" by switches at both ends, it kinked because there was no place for it to expand in either direction. Believe me, that section was smooth and straight, like the rest of Ken's trackwork, at the beginning of the session.


Moral of the Story: Always leave room for expansion of tangent track. (Curves will take care of themselves by altering their radii.)
 

·
Premium Member
Joined
·
4,626 Posts
Bill
I always wondered if you may have some troubles with that. the past year or so I have removed all my screws that hold the rail to the ties so the rail can move freely.
 

·
Registered
Joined
·
1,034 Posts
On my old layout, the track was screwed together and then screwed to 2x6 cedar.
It has been outside for about 22 years. I have never had problems with track expansion. I don't know if it's the type of roadbed or how the track is layed?
 

·
Premium Member
Joined
·
1,434 Posts
So what about LGB & TDV track from H&R trains that fastens it's rails to the ties using that damn bent joiner thru the tie trick? Has that ever been a problem with expansion? Did anyone ahve to go back adn unbend or unfasten the rails from the ties on either of those brands? Just curious really. I've got some of each and with teh prices today I'll be using EVERY last bit of track I have eventually.

Chas
 
G

·
So what about LGB & TDV track from H&R trains that fastens it's rails to the ties using that damn bent joiner thru the tie trick?


i had LGB tracks in hot tropical sun for years.
it expands in two directions. the rails are fixed just at one point to the sleepers. so they expand to the other end. really hot LGB tracks have the rails a bit longer on the end without railjoiner.
but since every piece of track does the same, there is no problem.
 

·
Registered
Joined
·
686 Posts
If I may, let me present a little science/math demonstration. In Ken's RGS Southern above, the track that buckled needed to be gapped as follows with the following known information.

Known:

Coefficient of expansion of aluminum rail = .0000123 inches per inch of length per degree of temperature rise.
Length of track needed to compensate for expansion
total temperature range

So.....

If Ken's striaght line track is 10'-0" long (120 inches), and say the total temperature variation is from say 20 degrees for a low and 100 degrees for a high for a total temperature variation of 80 degrees. Hence, 80 degrees times 120 inches times .0000123 equals 0.11808 inches expansion.

These numbers do not consider rail mounting (tight/loose/fixed) or roadbed (floating in ballast/attached to stringers/etc). And yes, the prototype railroads have the same expansion/contraction issues. I am familiar with Ken's section of the country, I was raised in NE Jersey. I spent many days and nights railfanning Pensy, and later Conrail.

Hope this is enlightening to some.

Bob Cope
 

·
Premium Member
Joined
·
5,510 Posts
Posted By armorsmith on 06/02/2008 6:11 PM
If I may, let me present a little science/math demonstration. In Ken's RGS Southern above, the track that buckled needed to be gapped as follows with the following known information.
Known:
Coefficient of expansion of aluminum rail = .0000123 inches per inch of length per degree of temperature rise.
Length of track needed to compensate for expansion
total temperature range
So.....
If Ken's striaght line track is 10'-0" long (120 inches), and say the total temperature variation is from say 20 degrees for a low and 100 degrees for a high for a total temperature variation of 80 degrees. Hence, 80 degrees times 120 inches times .0000123 equals 0.11808 inches expansion.
These numbers do not consider rail mounting (tight/loose/fixed) or roadbed (floating in ballast/attached to stringers/etc). And yes, the prototype railroads have the same expansion/contraction issues. I am familiar with Ken's section of the country, I was raised in NE Jersey. I spent many days and nights railfanning Pensy, and later Conrail.
Hope this is enlightening to some.
Bob Cope

Just some fun calculations based on the numbers...
Assume the following:
You have two 10-ft sections of nice straight track.
It is firmly attached at each end and cannot go anywhere AT THE ENDS.
The rail jointer in the middle is just a flimsy slip joint.
The rail itself is extremely stiff and inflexible such that if it is lifted in the middle it will become two perfectly straight ramps to the peak formed by lifting it.
It was laid when it was at the extreme cold temperature and no room for expansion was allowed.
It is now at the extreme high temperature of your example.
Thus, each section is now 0.11808 inches longer.
The only place for the expansion to go is to lift the middle up such that the rail is now the hypotenuse of a right triangle formed by the track bed and the elevation in the middle of the track.
How high is that middle of the track, now?
Pythagorean Theorem applies... A^2 + B^2 = C^2
"A" is the length of the track base (original length of the rail).
"C" is the length of the rail after expanding.
"B" is the height the middle of the track has raised.
Arrange the formula to solve fr "B": C^2 - A^2 = B^2
A= 120^2 = 14400
C = 120.11808^2 = 14428.35314
14428.35314-14400 = 28.35314285
The square-root of 28.35314285 = 5.324766933 INCHES!
Divide the rise by the run and you have a 4.437305777 percent grade from one end to the middle.
If the rail is not real real stiff, then it will sag and that will mean the length of the base will be less and thus the middle will be even higher.
Practical example...
My first track was that silly plastic stuff of 1-ft sections. I had it on four 10-ft 1x6 boards laying on the ground. I was afraid it would blow off and break the tabs that hold it together, so I nailed it down on the extreme ends of the track.
I don't know the temperature when I did this nor do I know the coefficient of expansion for the plastic.
I do know that a few days later is was quite warm and when I came home from work and drove into the driveway I noticed the track had assumed the shape of a bell curve with the middle at close to THREE FEET above the boards.
Like an idiot I walked over and touched the track and it fell over and broke several of the plastic tabs that hold the track together. /DesktopModules/NTForums/themes/mls/emoticons/crying.gif" border=0>
 

·
Premium Member
Joined
·
3,315 Posts
Great discussion. I absolutely must screw my track down, so I space the track.  Last year I experienced some difficulties with this, so I was particulary interested in this thread.  It's mostly trial-and-error here due to the extreme climatic conditions.
 

·
Premium Member
Joined
·
687 Posts
All very interesting and useful information.

If we translate into a normal practical situation, most of us lay our track in summer not in winter. Thus the amount of expansion to be coped with is perhaps 20 to 30 degrees on the heat side (not 80 or more). Secondly, if using flectrack (I use Llagas Creek 6 foot lengths) then an expansion gap should be left at each end effectively spreading the 10 feet of expansion in the example across three gaps (actually 1 full gap plus 2 half gaps or 2 gaps in total)

Now if you do the arithmetic ... .00001 inches expansion per inch per degree * 120 inches * 20 degrees divided by two expansion joints equals .01 inches Leave a gap of about 1/10 of an inch in each joint. A bit larger is usually helpful.

I actually take a coin (a quarter is just a bit fatter than 1/10 of an inch) and use that to gauge the joint trying to err slightly on the side of a wider gap.

I do understand that if the track is laid in a place where it is on rock and the sun shines directly on it, it can heat it way above the ambient temperature, this may lead to problems. so far, in my experience, I have not seen any buckling if a suitable expansion gap has been left and the track fully secured.

Regards ... Doug
 

·
Premium Member
Joined
·
3,315 Posts
Posted By Big65Dude on 05/09/2008 2:30 AM



Here's a graphic illustration of the effects of track expansion . . .



 Llagas Creek code 215 aluminum rail which "floats" on a foam roadbed - IOW, it's not secured to the underlaying base except at the switch



 




 



Moral of the Story: Always leave room for expansion of tangent track. (Curves will take care of themselves by altering their radii.)




I know that look !  I use the same kind of track. I have had to go back and re-install much of my track to prevent just this sort of thing from happening. 
 

·
Premium Member
Joined
·
3,315 Posts
Posted By Dougald on 05/08/2008 5:07 AM

Bill I too have aluminum rail - code 215 Llagas Creek well known for the tight tie to rail fit. My track is firmly fastened to a hard roadbed either pt 2x6 or a ladder made of TREX. Expansion joints are left at the end of each flextrack section. I spike every 12th tie or sometimes a bit more frequent if needed, with an aluminum nail to hold the track to the roadbed. The tendency for most modelers is to spike the tie with one nail in the middle but this leads to twisted ties as the rail expands because it will not slide through the ties without binding. I spike the ties with two nails through the tie ends outside the rail [/i]and leave the head slightly proud in case the track has to be lifted. I have had no problems with heat expansion. Regards ... Doug


Based on this post, I will be following suit and doing likewise. It sure makes sense to me.
 
1 - 20 of 20 Posts
Top