switches/turnouts.

[justme igor]

Source: TU Delft(the Netherlands)
Turnouts differ in sizes. Some commonly used ones are shown below. The number after '1:' stands for the angle of intersection. The length and the maximum allowable speed to pass the turnout in the divergent direction are given below as well.

1:9 - 32 meter - 40 km/h
1:12 - 38 meter - 60 km/h
1:15 - 47 meter - 80 km/h
1:34 - 99 meter - 140 km/h

.......

So when i am wanting to build my tracks prototypical correct and my "average real life speed" will be 70 km/h i will need a 1:15 turnout.
But when i do my calculations for 1:32 modelling i can not get the 47 meters, i get a 1 meter turnout that should be 32 meters in real life.
32 / 47 meters is in my scale 68,01 cm...
But i get a turnout of 102 cm...(would be in real life 99 meters aka 1:34---->140 km/h
With a radii of 581cm in: 1:9, 1:12, 1:15 and 1:34, so a radii below 5 meter is out of the question...need to redesign, no problem...time=problem
What do i miss here, where did i go wrong?
I dont think this question is appropriate to ask in class sinds we are handling prototypical and not model?
(studying railway engineering)

Thanks in advance, with best regards Igor

 

[Greg Elmassian]

First, the 1:9 divergence at the angle of intersection is normally called "Frog Number" and is measured at the frog, and the diverging rails are straight.

You specify a length, but what is this length, overall length (if so how far past the point of frog), or points to heel of frog, or ??? In other words without a precise definition of "length" nothing can be compared.

But worse, trying to map the constant frog angle to a curve is wrong, because the frog is not curved.

Two things are done in the hobby:

1. "sharper" turnouts, i.e. more strongly divergent are often made with curved rails up to almost the point of the frog. this makes it simple in sectional track to pull out a piece of curved track and put in a turnout.
2. As you move (in the hobby) to "less sharp" turnouts, manufacturers usually use the actual frog number and the diverging route is made of straight rail sections.

So when you are trying to match a radii to a frog number, all you can do is an approximation, and it really depends on how far past the point of frog the curved rails start.

So there is no way to easily make an equivalence. Basically most people cannot accommodate even a #6 turnout, and that is very sharp in mainline railroads, as further underscored that you started with a #9.

Therefore if you want to "match" a curve, you will have to prototype a turnout, then figure how far after the frog the curve starts and work it out. Realize that people usually use 20 foot diameter minimum who run large locomotives and even this is tight for a Big Boy loco.


My advice is to forget prototypical trackwork, you do not have the space for it. Just use the broadest curves and highest frog #'s on your turnouts you can.

Greg

 

[Rhinochugger]

First, the 1:9 divergence at the angle of intersection is normally called "Frog Number" and is measured at the frog, and the diverging rails are straight.

There's something lurking in the back of my mind that suggests this is specific to US practice. I believe that UK turnouts are curved throughout. I don't know what the European practice is.

 

[Greg Elmassian]

Well, a few pictures could easily solve this question, do you have any pictures of mainline turnouts?

remember we are specifically talking about the rails past the point of frog.... not the necessarily curved rails from the points to the frog, nor the track significantly beyond the frog.

Greg

 

[Greg Elmassian]

You can see several frogs here (be careful to see the rails "past" the frog, not other crossings. The rails are all straight right after the frog.

 

[Rhinochugger]

MMmmm, this is an interesting shot, as the purrrfect curves seem a bit clunky, but the right hand rail seems to have a continuous curve

 

[Rhinochugger]

This shot was identifying the catch point, but I'd say it's curved throughout.

 

[Rhinochugger]

You can see several frogs here (be careful to see the rails "past" the frog, not other crossings. The rails are all straight right after the frog.

Try this one Greg

It's from one of the Purbeck narrow gauge clay railway lines.

 

[Rhinochugger]

Got another one - we certainly don't have frog numbers in the UK

 

[Greg Elmassian]

I knew you jokers would find examples of curved switches...

Clearly curved switches do exist and they are curved.

So, if you look at MAINLINE switches designed for high speeds (of course you don't run trains as fast as we do), with the example that Igor stated:

"So when i am wanting to build my tracks prototypical correct and my "average real life speed" will be 70 km/h i will need a 1:15 turnout."

As usual, I am answering the original poster's original question.

None of what you guys posted are 70 km/h switches.... please, let's stay on track!!! Even what I posted are slower switches, but then they are probably not #9 or "more gentle".

Greg

 

[Rhinochugger]

I knew you jokers would find examples of curved switches...

Clearly curved switches do exist and they are curved.

So, if you look at MAINLINE switches designed for high speeds (of course you don't run trains as fast as we do), with the example that Igor stated:

"So when i am wanting to build my tracks prototypical correct and my "average real life speed" will be 70 km/h i will need a 1:15 turnout."

As usual, I am answering the original poster's original question.

None of what you guys posted are 70 km/h switches.... please, let's stay on track!!! Even what I posted are slower switches, but then they are probably not #9 or "more gentle".

Greg

I think the real issue is that in the UK, track laying practices have changed over the years, with pre-fabricated turnout sections used in many instances now, reflecting the sort of junctions that are likely to be seen in your post #5.

As I said, here in the UK we have never had point frogs referred to by number or type, so when considering accuracy, we need to consider the location and the period to be modeled.

Again, as I said earlier, I have no knowledge of European practice - indeed it may be that there were a variety of practices even 50 - 60 years ago and that more recently, knowledge and practices are shared.

As a slight aside (we were talking wheel standards on another thread) wheels standards differ between UK and US. While Flying Scotsman and one of the GWR Kings toured North America (and I've never read about adjustment to their wheel profile) the wartime USAT S160 class had problems running on UK metals due to the wheel profile but were seemingly less troublesome in Europe.

 

[Gavin Sowry]

The aforementioned curved frogs in Britain, are very old examples, from the days when everything was a custom fit. BR certainly now has 'straight' frogs, and turnouts to standard designs, one only has to refer to the Permanent Way Institute's fine tomme 'British Railway Track', a copy of which I borrowed when I was still at school, well over 50 years ago, and it had the straight turnouts then. That book had life changing influence on my career..... I became a Per Way Engineer (and I'm still there). Come to think of it, last Friday's drinkies was all Institute members.

Now, Greg mentioned 'Frog number'. This is usually just an American trait, as there are different recognised ways of measuring the frog angle. A #9 frog is NOT the same angle as a 1 in 9 frog in all cases.
Frog angle can be two times half the spread of the frog, or it could be using the tan angle measure (as used here in NZ). I believe curved frogs still have a following in Europe.
Our 1 in 9 has an angle of 6° 20' 25", (1 divided by 9 equals the tangent of that angle), and that is not the angle of a #9 frog. Don't spend too much time trying to understand all this, otherwise you'll have no time left to play trains !

 

[Gavin Sowry]

As a slight aside (we were talking wheel standards on another thread) wheels standards differ between UK and US. While Flying Scotsman and one of the GWR Kings toured North America (and I've never read about adjustment to their wheel profile) the wartime USAT S160 class had problems running on UK metals due to the wheel profile but were seemingly less troublesome in Europe.

Thread drift.... that's piqued my interest (I'm an expert at that). Yes, wheel standards. We won't let 3'6" South African locos (yes, there's a few over here) run on our 3'6" network, because the wheel standards are (significantly) different..... mainly the back to back causes them to jamb up in the frog flangeways. Think Rovex/Tri-ang trying to get through Shinohara turnouts.

 

[JimmyB]

Don't spend too much time trying to understand all this,

Or it will give you a headache

 

[Rhinochugger]

(of course you don't run trains as fast as we do)

Mallard

 

[justme igor]

I thank you all for your answers.
But the mistake was on my side...
I put the numbers the wrong way around that what was making it not sinking in...my mistake.
Pretty busy last 3 weeks incl studing and starting up second company with my brother plus tax for my first company, i saw a bit to much.

To sum some things up:
(all was made to there specifications and more important---->needs for that country.)
Most frogs are build to fit, there is not one the same.
There are some frogs of the self for standard points.
Basically every turnout for a certain line incl trolleys/trams have there own design for that speed or particular line.
Every period has its own demands for turnouts, thru out the years they are getting longer.
Frogs are in so many different shapes and sizes even in "my" area it would take 1 page alone to name them all..

The basic principle for turnouts, ~150 years ago, is still unaltered except some look alike ect ect.
The British railroad was heavily copied in the beginning.
Countries where slowly adapting to there different needs.

As far as i know of from the UK to Russia there all the same in there principal.
I suspect even in Africa, Japan China Australia and the great US of A

Curved, strait, y and many more, also in this one also there is no standard, just go where the track can be placed. And need some switch.
Frogs are in so many different shapes and sizes even in that area it would take 1 page alone to name them all..

Except for most EU stations and sidings there are "some standards" but they also change over time when the freight is getting heavier and more frequent and faster.
For passengers trains there are other demands like comfort and speed.
A heavy freight train will suffer a lot and the rails will suffer a lot if it must go on a passenger track especially the other way around, due to different vibrations.(passenger on freight tracks)

And yes i have room enough in the garden to even make turnouts for high speed lines up to 1:60 for 350 km per hour.
But my area is ~1920 to 1960 max. max 80 it is.
This is my goal, prototypical 1940ish track with the prototypical engines and roiling stock.
Yes i am fully aware what was driving and where...
But come on...the AA20 providing Amsterdam CS in the Netherlands with Russian coal....My great grandfather would love to see or drive that thing...
So oke not all will be prototypical

Thanks for reading

Thread drift.... that's piqued my interest (I'm an expert at that). Yes, wheel standards. We won't let 3'6" South African locos (yes, there's a few over here) run on our 3'6" network, because the wheel standards are (significantly) different..... mainly the back to back causes them to jamb up in the frog flangeways. Think Rovex/Tri-ang trying to get through Shinohara turnouts.

No not really a thread drift....
It contributed to the development of tracks and everything that drives on it....
The conjunction between comfort for passengers or the stiffness and load baring for freight trains, most country's have there own demands and everyone was experimenting.
Witch did not lead to a standard, even the gauges are still different.
South African loco's....Red devil if i am correct...beautiful loco

 

[Greg Elmassian]

Gavin, please explain how a 1:9 frog in the UK is different from a #9 frog in the USA, here the number is determined by the ratio of run to spread, and a #9 frog is 1:9 here in the US.

Igor, your post says you can do 80 kmh turnouts, from your post this says 1:15... you can do 1:15 in your garden? Or just a few turnouts. I've seen a German made switch in #10 and it is VERY long. What is your calculated length of the turnout in 1:15?

Greg

 

[justme igor]

The switch would be 1 meter 46 total, 3 meter for a scissor crossover/ordinary crossover

 

[Paul M]

Why do they call them frogs?

 

[Rhinochugger]

Why do they call them frogs?

Good question, well presented ...............................................