Darrell, CWR is used extensively on mainline curves throughout the US including the UP's Moffat Line with its 10-degree curves without expansion joints. The spikes have nothing to do with holding down the track. The purpose of the spike is to hold gauge. CWR is secured to the ties longitudinally with rail anchors (the "c" shaped devices positioned on either side of the tie) This prevents the rail from slipping and secures it to the tie which is firmly planted in the ballast. The practice is called "box anchoring" meaning that 4 rail anchors are used per tie (2 per rail) and placed tyically every other tie. Today most railroads are using resilient fasteners with wood and concrete ties to replace spikes and rail anchors mainly for economic purposes. the rail expansion device that you referenced is used typically on bridge approaches for long span structures because bridges expand at a different rate than normal ballasted CWR track.
Bob Frascella Wenham, MA On Thu, Mar 15, 2012 at 7:45 PM, Darrell <[email protected]> wrote: > ** > > > CWR can be stretched along straight track, which in many areas of the > country is endless miles. Curves, however, do not work well with rail under > tension. The spikes pull out. That is why the rail expansion joint I showed > in the previous post is used on curves. It eliminates the tension. > > The South Shore Line in northern Indiana has had welded rail for a few > decades now, and you can drive parallel to most of it. As you do, you will > see every few miles one of the rail expansion joints. If you know what > you're looking at. The thing is that although the line SEEMS to be > straight, it is not. Rail under tension would be a big problem on the > curves. > > And that's basically why we can't use tensioned rail on our model layouts. > We don't have enough straight track. You could easily do it if you have a > scale 10 mile run of straight track. Let's see, um, 52800 feet divided by > 64 = , um, ticka ticka 825 foot basement. OK, maybe you could even do it > with a 200' straight run....... > > Darrell > > > --- In [email protected], Robert Frascella <frascerj@...> wrote: > > > > Ed, > > > > In the real world Continuous Weld Rail is laid at a temperature where the > > maximum expansion is expected to occur. This is precalulated for the > > region or area of the country where the track is located. If the proper > > temerature of the rail cannot be achieved, then the rail is heated until > it > > expands to that temperature then welded together. Because steel has > > tremendous tensile strength, when it cools there isn't an alignment > problem > > if the rail is properly secured. The contraction during cooling is more > or > > less absorbed by the rail. (Problems sometimes occur when there is a > > defect in the steel and the cooling can cause a rail to break, but that's > > not typical) Heat expansion is the bigger problem. > > > > I guess we could use this principal in model railroading, but then we'd > > melt all those plastic ties:) > > Bob Frascella > > Wenham, MA > > > > > > On Mon, Mar 12, 2012 at 2:25 AM, Ed <Loizeaux@...> wrote: > > > > > ** > > > > > > > > > > > Not much of the track is soldered together > > > > This first kink was with SHS flex track. > > > > I wonder if the size of the rail has any effect on the expansion. > > > > > > The material the rail is made from will determine the amount of > expansion. > > > Different materials will expand at differing rates. > > > > > > > > > > I tried to not go end to end tight on the rails. I > > > > guess the rails will show be where I could have left more space! > > > > Bill Lane > > > > > > You might want to visually inspect those "former" gaps on a warm/hot > day. > > > If the ends of the rails now touch, that would be a good place to cut > a new > > > larger gap before the pressure builds up and leads to a kink. > > > > > > Question: In the real world, how do RRs prevent heat kinks when welded > > > rail is used for l-o-n-g stretches of track? With welded rail, there > are no > > > slipping expansion joints -- or are there? > > > > > > Cheers...Ed L. > > > www.sscale.org > > > > > > > > > > > > > >
