Can there be a Slip joint where rail can expand/contract?

[Robert Gift]

Much like a switch point, is it possible to have a section where one rail slides pasthe other to relieve tension from cold or pressure from hot expanded rail?

The stationary rail would have a long sharp "bevel" and the moving rail would slide against it.

A guard rail on the opposite side would keep flanges away from the sharp edge which would be kept well supported from being able to protrude inside.

Thank you.

Robert

 

[Pat]

Yes. Jointed rail does this thought with a butt end rather than mating tapers. To be effective a large number of slip joints would be needed. I suspect they would be a maintancne head ache and possibly negate the advantages of weleded rail.

 

[Damon Hill]

My rule of thumb is that if an idea is practical, it's probably already being done. If it's not being done, there's probably a good reason or several why.

 

[kenw]

Gaps of any kind are very damaging to wheels and are avoided as much as possible; expansion joints have gaps and therefore are minimized. A slip joint gap as you describe wouldn’t have any advantage over a butt-joint gap as there is still a gap at the area of the rail that the wheel contacts. (draw a skinny line on the rail and that's all the contact area there is.)

A joint like this would require special field equipment and such to fabricate on the spot and install, a standard butt-joint gap doesn’t.

Another concern would be that if for any reason the inside edge of the taper was forced (by expansion, vandalism or just wear and tear) too far inward, a nice pointed piece of track would be able to grab the flange and instantly derail the wheel.

 

[markgillings]

Much like a switch point, is it possible to have a section where one rail slides pasthe other to relieve tension from cold or pressure from hot expanded rail?

Yes. Just do a search for railroad expansion joints. The wikipedia entry for rail_tracks has a picture.

http://en.wikipedia.org/wiki/Rail_tracks

 

[roee]

These are typically used on large steel bridges. I know the Suisun Bay Bridge at Martinez, CA has two sets of expansion joints that allow for the rail to slip past and prevents rail kinks. These are separate from the lift rail joints. With the very large steel structure the entire bridge expands and contracts in the sun, and the thought is the joint prevent the rail buckle.

 

[Scarbagjack]

Hi, I think the simplest answer would be money.

Any joint like that requires maintenance, and that spells $$
All of us track mtce guys would all love to indulge our passion and maintain our infrastructure for the love only, but, that sort of love wont keep us warm and well fed and well content with the missus, eh?

Continuous welded jointless tracks are all the rage, seem to work at a high poundage and if installed with high quality steel, i.e. no squibs, then run a grinder/profiler over it every so often, and it hums along like a beauty.

Even now we have switchable "Ks" and swing nose crossings, all supposed to eliminate or reduce mtce requirements. I don't think that is always strictly true but I do know it reduces the romance and excitement of "Old Skool" railway sounds and sights.

 

[mixolydian]

ftp://ftp.wsdot.wa.gov/public/I-90H...- Summary of I-90 Floating Bridge Studies.pdf

"This report summarizes previous studies conducted on the I-90 (Homer Hadley) floating bridge relating to potential future light rail transit operations, identifies major issues related to the design of a transition rail joint, and correlates these prior work efforts with the recent I-90 floating bridge tests conducted by WSDOT/ Sound Transit."

 

[Robert Gift]

How interesting!
Thank you.
Is there some kind of lubricant applied to the sliding surfaces of the rails?
Surprised that there are no guard rails athe joint area.