Large Scale Central

Track plan

Track and Trestles
#61

Devon Sinsley said:

Oh and I guess I asked the question wrong. So what has been beat into my head in this conversation is that the difference between a toy switch and prototype switch is that the diverging closing rail must run straight through the frog. Now as it leaves the throw bar it curves toward the frog and at some point before reaching the frog it straightens out and runs straight. my question is how long does it need to run straight before entering the frog?

That depends on how long the curve is on the diverging stock rail. That curve in the point rail will match the curve in the stock rail.

When the point is throw over to the diverging route you’ll have to keep it in gauge with diverging stock rail.

#62

Its been my experience that the curved closure rail is a gentle curve from the point to the frog.  The stock rail matches that, then "goes off on a tangent," from there.   Follow?

#63

G1MRA standards…

http://www.g1mra.com/pdf/standard-dimensions-for-gauge1.pdf

http://www.g1mra.com/pdf/Standards-sheet-part-2-not-inc-wheels.pdf

#64

I guess it depends on what school of railroad civil engineering you went to. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)

#65

Ken Brunt said:

Devon Sinsley said:

Oh and I guess I asked the question wrong. So what has been beat into my head in this conversation is that the difference between a toy switch and prototype switch is that the diverging closing rail must run straight through the frog. Now as it leaves the throw bar it curves toward the frog and at some point before reaching the frog it straightens out and runs straight. my question is how long does it need to run straight before entering the frog?

That depends on how long the curve is on the diverging stock rail. That curve in the point rail will match the curve in the stock rail.

When the point is throw over to the diverging route you’ll have to keep it in gauge with diverging stock rail.

And thus you now understand why a #4 turnout is a much sharper turnout than a #7, and a #7 turnout is sharper than a #11, and a #11 turnout is sharper than a #22 turnout. It’s all about the ratio of the frog. The distance between the frog and the point is determined by the frog angle. If you look at the drawings I sent you, some of the points are 16’ 6" long (the actual point not the length from the point to the frog), while others are longer/shorter depending on the turnout size.

#66

So we’re all on the same page, here’s the technical names of each part. Are you referring to the closure rails or the point rails?

#67

Devon,

Maybe this will help you visualize the different turnout lengths, point lengths, and frog lengths. I thought about building a #22 turnout just to see how big the sucker is…

#68

I am not asking how long the diverging closing rail is from the point to the frog (point being the point at which it contacts the stock rail). I understand that its length is dependent on the frog angle. working from the frog toward the throw bar how long does the closing rail of the diverging track run straight before beginning to curve? Is this a set distance or is it a ration based on the frog angle and the over all length of the closing rail.

Now I understand everything has to stay in gauge. Lets think on this from the diverging stock rail instead. As Steve said the diverging stock rail gently curves away from the straight closing rail. How gently depends on the frog angle. Then at some point it heads off on tangent (straight line)( now I know where that term came from). What I am asking is what governs where the transition fro curve to straight happens. Now I am assuming that this is determined not by the stock rail but rather the closing rail and it approach to the frog. It needs to run straight before it hits the frog in order to run straight through the frog and not run in a curve.

So the question is where does it begin to run straight. Is this a set distance from the frog or is there a ratio or formula for where this happens based on the frog angle.

#69

Craig Townsend said:

G1MRA standards…

http://www.g1mra.com/pdf/standard-dimensions-for-gauge1.pdf

http://www.g1mra.com/pdf/Standards-sheet-part-2-not-inc-wheels.pdf

thanks for those

#70

Devon, aren’t you glad you asked? (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

#71

Steve Featherkile said:

Its been my experience that the curved closure rail is a gentle curve from the point to the frog. The stock rail matches that, then “goes off on a tangent,” from there. Follow?

Your saying then that it begins its straight path at the frog and not before?

#72

Devon Sinsley said:

So the question is where does it begin to run straight. Is this a set distance from the frog or is there a ratio or formula for where this happens based on the frog angle.

I’m sure it’s a ratio based on the frog angle and the point length, and the theoretical point of the frog.

#73

Most often. I suppose that there are exceptions, look at Ken’s example.

#74

Craig, look at your #20. The closure rail has a gentle curve from point to frog.

#75

Craig Townsend said:

So we’re all on the same page, here’s the technical names of each part. Are you referring to the closure rails or the point rails?

On your drawing there are no “point rails” there are closure rails and points. My question has nothing to do with what you have labeled as “points”. My question has to do with the diverging closure rail and by way of needing to stay in gauge the diverging stock rail. As the diverging closure rail bends toward the frog at what point does it begin to run straight. Instead of thinking in terms of single rails lets look at the diverging track as a whole as it leaves the straight rail it curves away. Then at some point it turns into a tangent, or straight run. Everyone has said that a prototype switch runs straight though the frog. This means that at the frog the diverging track is on the tangent and not the curve. But does the tangent begin at the frog point, just before the frog point, or does it start at some distance before the frog point.

Steve’s picture and explanation leads me to believe that the transition from curved to straight begins just before or right at the convergence of the two rails at the frog.

#76

Steve Featherkile said:

Craig, look at your #20. The closure rail has a gentle curve from point to frog.

Exactly my point the ratio of the curve or the degree of curvature of the closure rail is a some sort of ratio to the frog angle and the distance between the frog and the points. I think Devon’s over thinking this a bit… I sent him the NP engineering drawings for a bunch of different turnouts, so with that information he should be able to curve a closure rail to match.

#77

Craig Townsend said:

Devon,

Maybe this will help you visualize the different turnout lengths, point lengths, and frog lengths. I thought about building a #22 turnout just to see how big the sucker is…

None of this clearly shows where the transition from curve to tangent begins. It shows lengths of various pieces in relation to the various frog angles but not the point at which curve becomes straight. Lets just take the #20 above. Does curved track transition to straight 1 foot, 2 feet, 15 feet prior to reaching the frog point?

#78

Steve Featherkile said:

Devon, aren’t you glad you asked? (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

actually I am. For one I am always happy to learn and I always enjoy making people explain what they know, or think they know, or take for granted, or really do now but can’t explain to numb skulls like me.(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

#79

Craig Townsend said:

Steve Featherkile said:

Craig, look at your #20. The closure rail has a gentle curve from point to frog.

Exactly my point the ratio of the curve or the degree of curvature of the closure rail is a some sort of ratio to the frog angle and the distance between the frog and the points. I think Devon’s over thinking this a bit… I sent him the NP engineering drawings for a bunch of different turnouts, so with that information he should be able to curve a closure rail to match.

Nope still not answering the question. I am not asking about the ratio of the curve or the length of any rail. I am asking where said curve begins relative to the frog point.

#80

Steve Featherkile said:

Craig, look at your #20. The closure rail has a gentle curve from point to frog.

Steve is getting what I am asking. I think he is assuming that the curve begins immediately at the frog. Not any given distance from it.