when building a lift-out section, for example, I believe some amount of rail gap necessary to deal with wood expansion due to humidity.
In situations, like this, how much rail gap is reasonable before derailments become an issue?
greg - Philadelphia & Reading / Reading
I was running on a modular layout yesterday and wondered why my freight cars kept derailing at on location. I took a closer look and the bridge track was slid over so one side had a large gap - roughly 1/4 inch long. I moved it over to shrink the gap to about 1/8th inch or less, and it managed to go through ok after that. So probably less than 1/8th is a good max gap to shoot for.
Rio Grande. The Action Road - Focus 1977-1983
Very, very small. Paint any exposed wood so it won't react with humidity. I built my liftoff bridge from foam, mostly to keep it light, but it's a secondary advantage that foam doesn't get bothered by humidity or dryness.
Want a number? A sixteenth of an inch in HO. I've only got one liftoff section with track on it, and I've only had it a few months, so let that be a straw man that the more experienced among us can comment on.
It takes an iron man to play with a toy iron horse.
I've seen some modular layouts at shows that use rerailers at the liftout/tip up joints. Some of them have cut the rerailers in half, others have a full rerailer each side of the gap. Both seemed to work well, even if there was a little misalignment.
Good luck,
Richard
cowman I've seen some modular layouts at shows that use rerailers at the liftout/tip up joints. Some of them have cut the rerailers in half, others have a full rerailer each side of the gap. Both seemed to work well, even if there was a little misalignment. Richard
I allow a maximum of 2mm, slightly under 1/10 inch, at freezing temperature. That decreases as the weather heats up.
On curves that cross the joint diagonally, I install a guard rail against the inside rail opposite the gap in the outside rail. I also take a little diagonal bevel off the inside top of each rail on both sides of the gap. So far, that combination has kept me derailment free.
Chuck (Modeling Central Japan in September, 1964 - with lift out yard throats)
I control my train room's humidity, but not its temps quite so well. It can get very warm in the loft above my garage. However, rails will only expand about 1/4" over a contiguous 100' with a rise in temps of 30 deg F. Three small gaps here and there with tracks adhered with a thin layer of caulking will easily handle the rail expansion.
On my liftout, I try to leave gaps no more than 1/16". This is easily achieved by carefully cutting the ends of the rails at the end of the benchwork, and by doing the same on the liftout. Just have a positive alignment system, and have some kind of humidity control. If you can't do that practically, try for about 3/32".
As long as the gap isn't long enough for a wheel to drop too far, it shouldn't cause problems. I'd guess about 1/8" would be the maximum before I'd worry about it, and that's probably more than you'd need unless your layout is subject to periodic flooding.
Wayne
I laid flextrack clean across my liftout section. Tested it, ran trains for a while. When happy with it, I cut rail gaps at the right places, using my Dremel. Dremels won't cut straight down, unless you have scary big cutoff discs. Just arrange your cuts so that the slight tilt in the cut allows the liftout section to lift straight up.
David Starr www.newsnorthwoods.blogspot.com
I have 1/16th gaps on my double track swing bridge and Bascule bridge and operate them a lot, with no problem's. Contrary to what some people think.....the rail itself Does Not expand or contract...what it is adhered to does. If You glue and screw Your lift out sections, it will help a lot in controlling movement.
Take Care!
Frank
working on a vertical staging yard. multiple 1x4 shelves slide vertically like a window and need to align with the layout bench.
I believe I need to allow a gap to allow for expansion/contraction of the layout benchwork, shelves, house. May not know how much of a gap until a rainy week in the summer.
Gregc,
Hopefully, You won't have to contend with lateral movement also and don't scrimp on Your choice of lumber. Like I said, I screwed and glued all my bench work.....then got lazy and bought a air brad nailer instead of using screw's, much faster and easier to use.
Did the train roll over it without derailing? Then the gap is ok.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
A 3 foot section of nickel silver rail will change length by .004 for each 10 degree F change.
Ed
7j43k A 3 foot section of nickel silver rail will change length by .004 for each 10 degree F change. Ed
The naked eye cannot even see that.
Btw: That is also under extreme weather condition swings....anyone that would build a layout in those conditions would have to have a screw loose, some where. LOL
zstripe 7j43k A 3 foot section of nickel silver rail will change length by .004 for each 10 degree F change. Ed The naked eye cannot even see that. Take Care! Frank Btw: That is also under extreme weather condition swings....anyone that would build a layout in those conditions would have to have a screw loose, some where. LOL
7j43k
Nothing that a cut from a Dremmel Tool cannot fix.
Due to the shape of my basement and an expansion I'm planning, it will have 2 liftout sections. I plan on drilling and doweling from the top. That should take care of the horizontal alignment. The supports at each end will be carefully aligned to handle the vertical alignment. Once the section is constructed, the track will be laid across the sections and ballasted to ensure that the track is solidly secured in place. THEN, I will cut the gaps using my Dremel. If you cut the rails with the Dremel over the liftout section, the angle will be such that it will lift straight up. Power to the lifout section will be run directly to it using connectors, then the approach tracks will be fed off those connections. That way, when the lift out section is removed, power to the approach tracks will be cut, as well. No worry about any imitations of "The Bridge on the River Kwai".
Marlon
See pictures of the Clinton-Golden Valley RR
Due to a cutting snafu by the operator and expansion/contraction issues in central Texas the gaps in my liftout vary from 1/16" to 3/16" during the year. I agree with others that the 1?16" gap should be the ideal but I have actually had very few derailments even given my greater gap at times. Now my liftout is on a straight length of track which makes a difference. Also, I plan to add split rerailers at each end which should eliminate any future problems.