G Scale Model Train Forum banner

1 - 11 of 11 Posts

·
Premium Member
Joined
·
80 Posts
Discussion Starter #1
Hi,
 
I have about 50 feet of straight that is starting to bow during the day.  Is the best solution Hillman’s Expando Rail?
 
If so, do I cut the rail when it’s cool and remove enough to allow the expando rail to fit fully extended?  Or cut duriing the day and add the expando rail fully closed?
 

·
Premium Member
Joined
·
749 Posts
Wouldn't the flange get caught in the groove(causing a derail) if the front trucks hit them just right?

Andrew...
 

·
Premium Member
Joined
·
4,716 Posts
I've thought of that, but I've never heard of it happening.

Yes, Marty makes them himself. I think there's a thread on the old forum.
 

·
Premium Member
Joined
·
2 Posts
Hi

Good question about when do you fit the expando rail.  I hadn't thought of this before but here is my reasoning....

I would see if you can work out the difference in the length at high and low temps - this should give you an idea of the amount of expansion you are dealing with.  If the expansion is more than the "give" of the expansion rail, you probably need more expansion sections.  I don't know the expansion/contraction rates of the material in your track, we could work it out (50 ft x expansion rate due to heat).  The bowing would also be related to the temp. when you layed the track out in the first place but not much you can do about that now.

Assuming you don't have that much expansion and only need one expansion section, you could try one of three options:

1) Fit it when the rail is at its hottest, with the expansion rail near (but not at) its minimum.  As the rail cools, it should extend the expansion rail as the rest of the rail contracts.  I wouldn't set it at the minimum, as you may well have a hotter day (global warming /DesktopModules/NTForums/themes/mls/emoticons/sad.gif  or just bad choice of "hot" day). 
2) Fit it on a very cold day with the expansion nearly at a maximum. 
3) Pick an average day with the expansion rail set in the middle of its expansion capacity

OK - so that probably didn't help very much, but with all the really helpful and experienced people in this forum, I am they will be able to see the flaw in my logic and correct me!

regards

anthony
 

·
Premium Member
Joined
·
631 Posts
I have long runs of track across my hill. Approximately 120 of straight track in 4 locations. IT MOVES!! Most of it is free floating on 2x lumber with no ballast. Every winter it pulls its self a part at the weakest rail clamp. The clamp isn't weak, it is just not the tightest. Every summer the track expands and slides off the 2x road bed support.

I am in the middle of the East Coast of US, so I am sure those farther north or south have wider temperatures respectively.

I have purchased a dozen ExpandoRails from Hillman last year. Where I have installed them, they work great. The paper that comes with it suggests to install it as described above. It says that they are designed to accomodate 150 degrees F at 30 feet of track. The gap is 5/8 inch. I am not going to install them every 30 feet, but intend to place them where the stress seems greatest, i.e. where the track comes apart in the winter.
 

·
Premium Member
Joined
·
5,510 Posts
Posted By Richard Weatherby on 03/09/2008 6:33 AM
I have long runs of track across my hill. Approximately 120 of straight track in 4 locations. IT MOVES!! Most of it is free floating on 2x lumber with no ballast. Every winter it pulls its self a part at the weakest rail clamp. The clamp isn't weak, it is just not the tightest. Every summer the track expands and slides off the 2x road bed support.

I am in the middle of the East Coast of US, so I am sure those farther north or south have wider temperatures respectively.

I have purchased a dozen ExpandoRails from Hillman last year. Where I have installed them, they work great. The paper that comes with it suggests to install it as described above. It says that they are designed to accomodate 150 degrees F at 30 feet of track. The gap is 5/8 inch. I am not going to install them every 30 feet, but intend to place them where the stress seems greatest, i.e. where the track comes apart in the winter.


My track is about 150 ft in two joined loopbacks.  The loops are about 17ft diameter curves (8-9ft radius). All I used was the slipon joiners.  When I assembled it I used a dime to hold the ends of the rails apart as "room for expansion". The track was layed when it was in the 80's and 90's.  The track is all up on 1x6 boards (totally elevated structure for Live Steam).  Originally the track was just laying on the wood surface where grain irregularities and nap can sometimes catch the edges of the ties and keep them from shifting.

I figured the expansion rates and what that would do to the sizes of the loops and all that.  I must have gotten a really bad table of expansion rates for nickel-silver as the track moves two or three times as much as the calculations came out.

When the track expands, two things happen... the joiners MIGHT do what one would expect and the dime thick gaps close up (if the ties get hung-up on something).  Or, the track continues to expand and the loopbacks get bigger... by a couple of inches and thus overhangs the outside edge of the 1x6 surface of the structure.

When the track contracts as the temperature goes down, the joiners do NOT release the track until something catches a couple of ties to hold the track in place.  So what happens is that just ONE joiner (the loosest one) lets go and all those dime width spaces collect at that place and I then have a gap that can be up to 3/4-inch wide and a lot of work to jiggle the track around to get the gap back together.

Now the track is floating "ON" ballast (it is too light to float "IN" the ballast) and all it does is contract a couple of inches in diameter and overhangs the inside edge of the structure and in the loopbacks there are no gaps in the track at all. 

But then there is the track between the loopbacks! There is a lift out section for the middle of that and I have to have two sections of track to fit there.  One is about an inch longer than the other... to make up for the difference in track length between hot days and cold days.  I have to do lots of jiggling of the track in both loopbacks to account for the lessor differences when the distance between the loopbacks is not exactly the length of either of the lift-out sections.

I have often wondered if the "Expansion Track" sections would alleviate some of this fiddlin' with the track, but I fear I would have to purchase one "Expansion Track" joint for every joint in the track as it stands now. And even then, just the weakest one (the one that slides the easiest) would do most of the "work" and the others would stick someplace and the loopbacks would continue to change in diameter.  I guess they would lessen the amount of jiggling to get either of my lift-out sections to fit.
 
1 - 11 of 11 Posts
Top