What does each one accomplish that another one may not? Advantages, disadvantages, etc.
In using 2 switches to create a crossover in parallel main lines, what is the centerline distance of main lines for each number?
Each increase in size numerically makes them longer physically with a corresponding smaller diverging angle. And the smaller the diverging angle; the faster speed your trains can negotiate the crossover.
The center-to-center (CTC) distance between the mainline track would be contingent on how long the diverging track is when the two diverging tracks are abutted together. Each manufacturer's turnout (switch) may and most likely will be different from one another. You may need to place a piece of flex track in-between so that the CTC distance of your mainline track is adequate enough for two passing trains running in parallel.
Other considerations are 1) how much room will you have on your layout for a crossover and 2) how long are your longest locomotives?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
My general rule for turnouts is to use the biggest one that will fit.
Everything in my collection will negotiate a #5 turnout, but bigger is always better.
-Kevin
Living the dream.
Lastspikemike Frog number and parallel track center lines are not related... {I stopped reading here...}
Frog number and parallel track center lines are not related... {I stopped reading here...}
I'm going to take a wild stab and guess that geometry isn't your long suit. Track laying probably included.
Of course they're related, in the same way the diameter of a circle is directly proportional to the radius, and the circumference has the same relationship, with the calculating benefit afforded by Pi (3.14159).
Suppose you had a turnout, but instead of a diagonal diversion it is a 90 deg diversion. We call them crossings, but I digress. Does the angle of the diversion differ from that of a #8 frog? Yes, it does. And how far does one run the diversion in either case before one should consider truncating the length to create a parallel track? Wouldn't that also depend on the angle of diversion? Why yes, it does.
As in so many things, it isn't just one factor, and one can ignore the others that actually matter. As the angle of divergence changes, so must the length of the diversion if.......IF...one wants a parallel track that doesn't encourage contact at any point when two items are following those proximal parallel routes.
To help situate this, suppose the divergent angle is that of a #8. You place two turnouts opposite each other points-wise, and the length to complete the transit over to each other totals 6". Wait, you decide to use a #6 instead because you're daft, if capricious and crafty, and find that now you must trim one of the diverging lengths. Oh yes you will. Try it and see. You'll also have the kink in the middle of the cross-over route, and if you know geometry, you'll know why.
selector Lastspikemike Frog number and parallel track center lines are not related... {I stopped reading here...} I'm going to take a wild stab and guess that geometry isn't your long suit.
I'm going to take a wild stab and guess that geometry isn't your long suit.
Rich
Alton Junction
1arfarf3In using 2 switches to create a crossover in parallel main lines, what is the centerline distance of main lines for each number?
the frog number (e.g. #4, #6) is a measure of the frog angle (see Turnouts) in terms of the ratio of the distance from the tip to the separation of the rails. the larger the frog number, the smaller the angle
in a crossover, a longer distance will be needed the smaller the angle.
the distance from the points to the frog, the lead length, is also longer the smaller the angle.
greg - Philadelphia & Reading / Reading
I went with code 83 Atlas #6 turnouts for my mainlines and #4 for my yard. My longest locomotives easily negotiate the #6 turnouts at full speed (70MPH scale). They also negotiate the #4 turnouts at yard speed (under 15MPH scale).My longest rolling stock is scale 72’ and all negotiate the #4 turnouts, early on I had several 85’ passengers cars that also cleared the #4 turnouts. The 85’ cars looked ridiculous on my small 14’x 10’ layout. I built a #6 double crossover for 2” CTC track separation that works perfectly at full speed.
https://melvineperry.blogspot.com/2012/06/june-25-2012-my-double-crossover.htmlCommercially manufactured code 83 double crossovers won’t pass my Rivarossi deep flanges without problems but the Atlas turnouts work perfect with deep flanges. Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
The op's question has been answered very well by many more knowledgeable than I.
To reiterate, the larger the number, the shallower the angle of the diverging route and thus the larger and longer a turnout. #4-#10 all hold a place in model railroading. Going to run huge steamers? Get #6-#10. Running small steam with some early GP's? #4s will suffice.
It's all in your equipment, and more importantly, the space you have to work with. My layouts neccesitate smaller turnouts. Like a peco #2. They look great in industrial areas and allow me to create fun track formations. I use 6's and 8's too however. They look right at home on the mainline.
It come down to three things. You're equipment, your space, and your preference. Notice the common word?
Psst! The answer is your!
JJF
Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing.
Yesterday is History.
Tomorrow is a Mystery.
But today is a Gift, that is why it is called the Present.
I don’t think anyone so far has given the most useful answer. Frog number and minimum radius should be in balance. If your minimum radius is 22” in HO scale (for example), that’s roughly equivalent to a #4½ (what Atlas labels their “#4”). So a #8 turnout in that situation would be wasteful overkill, since your trains must negotiate the much-tighter curves. If you let folks know your minimum radius, someone may be able to help. (Some others will only talk.)
Byron
Layout Design GalleryLayout Design Special Interest Group
yes, the distance between the track centers can be whatever is desired, perhaps requiring a short piece of connecting track.
but the overall length of the crossover will be longer depending on the frog number
cuyama I don’t think anyone so far has given the most useful answer. Frog number and minimum radius should be in balance. If your minimum radius is 22” in HO scale (for example), that’s roughly equivalent to a #4½ (what Atlas labels their “#4”). So a #8 turnout in that situation would be wasteful overkill, since your trains must negotiate the much-tighter curves. If you let folks know your minimum radius, someone may be able to help. (Some others will only talk.) Byron
I noticed also that the asnwers have been lacking. Good point that using long turnouts when curve radii are sharp makes little sense. As for talking, so true!
1arfarf3 What does each one accomplish that another one may not? Advantages, disadvantages, etc. In using 2 switches to create a crossover in parallel main lines, what is the centerline distance of main lines for each number?
As others may have mentioned, the higher the switch number, the broader/longer it is and it can handle longer rolling stock, as a rule.
The #4 (Atlas is a #4 1/2) are used on small 4x8 layouts due to space restrictions but do not work well with long rolling stock.
My personal minimum is a #6 for yards ladders and sidings, and for crossovers, #8. But my minimum radius is 32" or broader.
A cross over is basically an S curve, so you want it to be gentle to allow longer cars to pass through with hopefully no issues.
Rio Grande. The Action Road - Focus 1977-1983
There is one other factor. Real railroad crossovers will be #16 and up. Even then they are reduced speed. The limiting factor is going to be how much space you have for the crossing.. if you are making a 4' x8' you are pretty much going to be limited to #4 turnouts. #6 and higher will eat up nearly all your straight section. As usual everything we do on modeling is a compromise of real railroads
Best to draw your plan with a template that also has various turnouts on it. When I was 18 I designed a yard with 8 tracks and all the turnouts fit in a one foot length on my hand drawn plan. Didn't turn out that way in real life.
LA #4 Wye will have, in effect, two #4 frogs cast together as if each diverging route were to be from the straight through route on a #4 turnout.
Not correct (semantics aside). For most manufacturers such as Walthers and PECO, what they call a "#4 Wye" turnout is actually the equivalent of a #8 frog. Very gentle curve through the turnout on either leg.
Depends on the situation. Imagine a layout built along one long wall of a basement on 24" wide shelfs. At the ends, it widens out to 4' wide to allow return loops of 22" radius. On the main part of the layout, you could use larger turnouts (say no.8s or 10s on the mainline, and no.6 for spur tracks) for a more prototypical look. The loops at the ends could be disguised by scenery. Yes, you could only run equipment that can handle 22" radius, but you wouldn't have to build the whole layout with that limitation.
wjstixThe loops at the ends could be disguised by scenery. Yes, you could only run equipment that can handle 22" radius, but you wouldn't have to build the whole layout with that limitation.
i think Byron is suggesting that the loops at the end could use a #4 wye instead of a #4 turnout to allow a greater radius and such that the "rest of the layout" is limited by a #8 turnout
(wow, never realized that)!
wjstixDepends on the situation. Imagine a layout built along one long wall of a basement on 24" wide shelfs. At the ends, it widens out to 4' wide to allow return loops of 22" radius. On the main part of the layout, you could use larger turnouts (say no.8s or 10s on the mainline, and no.6 for spur tracks) for a more prototypical look. The loops at the ends could be disguised by scenery. Yes, you could only run equipment that can handle 22" radius, but you wouldn't have to build the whole layout with that limitation.
Sure. But is that the OP's situation? After designing a couple of hundred layouts for others, no one's ever asked for this, except maybe in one scene.
gregci think is suggesting that the loops at the end could use a #4 wye instead of a #4 turnout to allow a greater radius and such that the "rest of the layout" is limited by a #8 turnout
Doesn't matter how you feed the 22" radius mainline curve – it's still 22" radius and that's the determining factor for what will run reliably.
Rhetoric is not the same thing as knowledge.
Obfuscation is not the same thing as help.
cuyama...what they call a "#4 Wye" turnout is actually the equivalent of a #8 frog. Very gentle curve through the turnout on either leg.
Absolutely correct...I have four #4 wye turnouts on my layout, three of them in a wye meant for turning locos and some short trains...the points follow exactly the 30" radii of the tracks in which they're installed - no jarring or jumping, just as smooth as if there was no turnout there at all.
Wayne
Lastspikemike I'm not following how 2 x 4 is not = to 8 in railroad land?
the frog # is measured as the distance between the diverging rails. but on a wye, neither is straight
Yes on a wye the tracks are both moving away from each other, it isn't one track staying straight and the other diverging.
Think of it this way...imagine a straight line drawn on the benchwork. Then imagine a straight track centered over the straight line. That straight track then ends in a #4 wye. The track diverging to the right diverges from the straight line on the benchwork at the same angle as a no. 8 turnout would. The track diverging to the left also diverges from the straight line at the same angle as a no. 8 turnout. Since the two tracks are both diverging from the straight line, the result is a no. 4 wye turnout.
OR
Think of it this way. Take a no. 8 right hand turnout, and a no. 8 left hand turnout. Lay one on top of the other so the straight tracks of the turnouts are one directly on top of the other. Then take a no. 4 wye and lay that on top of the two no. 8 turnouts. The angle of the tracks of the no. 4 wye match the diverging tracks of the two no. 8 regular turnouts.
It can be difficult to grasp. It's kinda like how 1/8 is half of 1/4, even though 8 is bigger than 4.
The key is the frog angle. On a straight turnout, one frog rail parallels the through route. The opposite frog rail parallels the diversion. What is the angle of the frog rails relative to each other? Picture that.
Now, along the same centerline, you have the same frog, but it services two diverging/flaring routes. Won't the formerly parallel-to-the-centerline through frog rail now be angled to permit the second divergence, whether left or right? If the angle of divergence relative to the centerline up to the points is a #8 turnout, the angle at the frog that permits two divergences is going to be twice the divergence as before...and so the angle now doubles to a #4.
cuyama Rhetoric is not the same thing as knowledge. Obfuscation is not the same thing as help.
Mike
Lastspikemike A prototype #4 turnout will diverge at twice the angle of a #8 turnout. I'm not following how 2 x 4 is not = to 8 in railroad land?
A prototype #4 turnout will diverge at twice the angle of a #8 turnout. I'm not following how 2 x 4 is not = to 8 in railroad land?
The frog angle is the arc tangent of the reciprocal of the frog number.
ATAN(1/4) = 14.036
ATAN(1/8) = 7.125
14.036/7.125 = 1.97. Which is not = 2.
For a constant centerline separation, the length for a #8 crossover will be twice the length of a #4, but it's incorrect to say that the angle of a #4 frog is twice that of a #8.
Ray
Lastspikemike cuyama L A #4 Wye will have, in effect, two #4 frogs cast together as if each diverging route were to be from the straight through route on a #4 turnout. Not correct (semantics aside). For most manufacturers such as Walthers and PECO, what they call a "#4 Wye" turnout is actually the equivalent of a #8 frog. Very gentle curve through the turnout on either leg. A prototype #4 turnout will diverge at twice the angle of a #8 turnout. I'm not following how 2 x 4 is not = to 8 in railroad land? If this is the case for model turnouts then logically a #4 Wye will behave the same as two successive #4 turnouts. The angle of divergence from tangent of a #4 Wye will be the same 7 degrees or so as a #4 turnout. So two #8 frogs back to back = a #8 frog. In railroad land 4 divided in half = 8....what a surprise....
cuyama L A #4 Wye will have, in effect, two #4 frogs cast together as if each diverging route were to be from the straight through route on a #4 turnout. Not correct (semantics aside). For most manufacturers such as Walthers and PECO, what they call a "#4 Wye" turnout is actually the equivalent of a #8 frog. Very gentle curve through the turnout on either leg.
L A #4 Wye will have, in effect, two #4 frogs cast together as if each diverging route were to be from the straight through route on a #4 turnout.
If this is the case for model turnouts then logically a #4 Wye will behave the same as two successive #4 turnouts. The angle of divergence from tangent of a #4 Wye will be the same 7 degrees or so as a #4 turnout.
So two #8 frogs back to back = a #8 frog. In railroad land 4 divided in half = 8....what a surprise....
As has probably been covered, the frog # represents the angle between both tracks. Its just that with a wye, there is no tangent since the frog is essentially "rotated" a bit compared to normal, making two equal diverging paths.
So the #4 frog in a wye has the same effect of a #8 frog if there was an actual tangent route.
And a #3 wye uses a #6 frog, and a 5 a 10.
- Douglas
LastspikemikeIt's hard enough to understand that 8 is a smaller number than 4.
Ever buy wire? Just sayin'.
Frog-1 by Edmund, on Flickr
Frog_fig9 by Edmund, on Flickr
Frog_0001 by Edmund, on Flickr
Seems like we've covered this territory before.
THAT thread wound up being locked.
https://cs.trains.com/mrr/f/88/t/289313.aspx
Good Luck, Ed
Hi,
Without getting involved in math, let me attempt to answer your query....
I've made (with success) HO double crossovers of both "6s" and "8"s, using Atlas code 100 trackage. Both size turnouts allowed for my largest locos (E units, BLI 2-10-2s and 4-8-4s) to cross with ease. The big locos certainly looked better crossing on the #8s vs. the #6s, but both worked well.
Of course the higher number turnouts cost you space - which may or may not be a factor.
As far as the separation of parallel tracks, the length of the diverging track is as important as the turnout number. From what I gather, different mfg. turnouts have different lengths on their diverging tracks. You certainly could add spacer tracks, and with care, you could shorten the diverging tracks as well.
All said, we need to tailor the turnout type/number to the layout space we want to use. And if we are using bigger locos and longer cars, the higher number turnout we use the better.
ENJOY !
Mobilman44
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
Generally speaking, longer is better but eats up space so like so many things in this hobby, it becomes a tradeoff. I have a large layout so I have room to use the longer turnouts. A #10 is getting close to prototype. I've found #8 handles the largest locos and passenger cars and it is my standard for mainline crossovers and sidings. I had to replace an Atlas #8 and didn't have another on hand so I've put in a #6 temporarily paired with a #8 to create a crossover and it has handled all my locos with no problem. I haven't ballasted it yet and am debating whether to replace it with a new #8 or leave well enough alone. I use #6 in my yard and spurs although I have cheated in some tight industrial areas and used a few #4. My shortline which branches off my mainline and runs shorter equipment uses a mix of #4 and #6.
SeeYou190 My general rule for turnouts is to use the biggest one that will fit. Everything in my collection will negotiate a #5 turnout, but bigger is always better. -Kevin
My 2 cents - This answer really is the answer. Short and sweet and simple.
Draw a line on a piece of paper. Take a ruler, and make a dot 1/8" on one side of the line, and another dot 1/8" directly across the first dot, but on the other side of the line. The two dots are 1/4" apart. 1/8" + 1/8" = 1/4".
If a straight track ends at a wye, and the track on the right diverges on the angle of a no. 8 turnout, and the other track diverges the other direction like a no.8 turnout, the frog has to be a no.4 frog.