3-way tandem turnouts

[martin_wynne]

3-way tandem turnouts

 

by martin_wynne

 

original page on Old RMweb

__________________________________________

 

??? posted on Sat Aug 23, 2008 11:34 am

 

mines a pint wrote:

Of the things I have yet to master (slips and 3 ways) I really need to sort this one out, Ive watched the video 3 times and it still ain't making sense.

Hi Russ,

 

There's an explanation of what's going on in the video in this thread: http://groups.yahoo....group/templot/m ... 7?expand=1

 

Here are the relevant bits copied to RMweb:

_______________________________________

 

Dear all,

 

Here is another video. This shows the basics of creating

3-way tandem turnouts.To ring the changes this one

is in S gauge:

 

http://www.templot.c..._way_tandem.exe

 

Camtasia player, 11 minutes, 11MB file.

 

Select Open after clicking the link and you can safely

ignore any warnings.

 

Navigating the video:

 

Press the space bar to start and stop. Once started and

stopped at least once, the right and left arrow keys can be

used to move one frame forward and back at a time. Or you

can drag the top slider to find a specific frame. There are

more options by right-clicking on the picture. You can drag

the video to one side by grabbing on the picture area.

 

Despite the presence of a volume control, this video is silent.

 

Refer to the elapsed playback time showing at the bottom

right below the picture to follow these notes below.

 

To keep the file size sensible I made some preliminary

example template settings in the usual way:

 

The 1st base turnout is a B-8 LH on 3000mm radius.

 

The 2nd turnout is an A-7 RH, blanked up to the switch toe.

 

Both turnouts have square-on timbering with in-line ends.

Some timbering has been omitted (shove timbers) to keep

things less cluttered. The track centre-lines are not needed

and have been turned off (in the generator) for the same

reason.

 

These templates are showing in marker colours with the

intent to improve clarity, although I'm not sure this worked

out too well.

 

There is a lot to say about tandem turnouts, and I can't

put it all in one email. Tandems can be single or double-sided,

and the second switch can be in either the main road or

the turnout road of the first switch. Each of these need

a slightly different approach. This example is a double-sided

tandem with the second switch in the main road of the first.

 

As always in Templot there are several different ways to

achieve the same result -- you may prefer to do things

differently. Here we go:

 

1. 00:00 - 00:55 elapsed time

Align the 2nd turnout over the 1st and snake it into position.

(I wiped the 2nd turnout to current to keep an unused copy

of the original in the storage box, in case I need to revert

to it for any reason.)

 

In aligning the two turnouts, bear in mind that:

 

a. there must be room to open the second blade behind the

first and accommodate a slide chair for it, and at least a

bolted half-chair for the first switch rail, and

 

b. the location of the middle V-crossing (crotch frog) must

be far enough from a running rail to leave room for the

wing rails, and

 

c. the main V-crossings (frogs) must be far enough apart

to allow their check rails to be properly positioned.

 

More about all this at:

 

http://groups.yahoo....ot/message/4900

 

and in this picture:

 

http://www.scalefour...es/chairs-4.jpg

 

Having aligned the two turnouts, if you are still working on

your track plan I recommend that you stop right there.

Come back and finish the rest when the track plan is finalised.

Otherwise a lot of work will be wasted and need to be

done again if you later need to modify the main road

radius or the turnout sizes.

 

2. 00:55 - 01:30

Make a note of the "turnout radius (centre-line)" for each

of the turnouts. This is the required radius on each side

of the middle crossing. For best results we use the largest

radius side as the main road of the middle crossing.

 

In this case the 1st turnout has 1426mm radius and the

2nd turnout has 7402mm radius. So we choose the 2nd

turnout as the main road of the middle crossing -- which

will therefore need to be left-hand, with a negative main

road radius of -7402mm.

 

3. 01:30 - 02:30

So make the 2nd turnout current and slide the peg along

the turnout-road crossing rail until it is somewhere near

the middle crossing. The exact position does not matter.

Store it again, and set a distinctive marker colour (optional).

Bat its name label out of the way (optional).

 

4. 02:30 - 04:00

Get a new turnout template and set the curving to -7402mm,

as previously determined. (Alternatively you could adjust it

later to align, using F6 mouse action.) Temporarily turn

off the timbering.

 

Guess a near size for the crossing angle, here I set 1:4.5.

 

Select the longest switch available. This is a temporary

suggestion until gaunt turnouts are available in a later pug.

(I will expand on this separately.) I set a 30ft straight switch.

 

Change the V-crossing to "curviform" so that the radius on

each side can differ (this is important).

 

5. 04:00 - 04:55

This time run the peg along the main-road crossing rail.

Omit the unwanted rails, and shorten template to a more

convenient length.

 

6. 04:55 - 05:20

 

Align it onto the 2nd turnout at the peg. It is likely to be

facing the wrong way, so dab the Multiply key to correct

that. (This works whenever the peg is already on the

notch.)

 

7. 05:20 - 06:25

Zoom in and snake it into position until the f.p. marker

(white cross) is exactly aligned over the intersection in

the underlying rails. Then put the peg there (Ctrl-4,

this is important), and zoom back out a little way.

 

That's enough for one email. To be continued...

___________________

 

... continued:

 

Now we need to adjust the crossing angle for

the middle V-crossing (crotch frog) to match

the underlying rails. We are apparently adjusting

a full turnout including a switch. But we shall be

using only the crossing part, so what happens to

the switch is immaterial.

 

For the following it is essential that the peg is on

the f.p. (Ctrl-4), and that you have pressed this

only once (or an odd number of times), so that the

peg arms are aligned along the main road as shown.

 

8. 06:25 - 06:35

Set F5 options to allow any crossing angle (fully

variable instead of snapping to nearest 1/4 unit angles).

 

9. 06:35 - 06:50

Select F5 mouse action to adjust the crossing angle.

Then immediately right-click and lock the switch on

the menu. The info bar changes to pink to indicate

that the switch is locked and won't change. (Normally

F5 changes the switch size to match the crossing

angle for a sensible turnout. If this happens here it

would make matching the rails confusing).

 

10. 06:50 - 07:05

Adjust the crossing angle until this V-crossing matches

the underlying rails on the 1st and 2nd turnouts. On my

example you will see that the result is a crossing angle

of 1:5.15 (RAM).

 

(On the prototype the nearest standard 1:5 crossing

components would be used and faired in to a best fit

to the ruling curves. If you feel so minded you can now

try this in Templot. Change to a 1:5 crossing, and a

straight half-diamond template, reset Ctrl-4, blank up

close to the knuckle (Ctrl-F3), and try using F8 to rotate

around the fine-point to find the best fit. You will need to

split off the full check rails as a separate partial template.)

 

11. 07:05 - 07:45

Adjust the overall length (F4) and blanking length

(Ctrl-F3) to just contain the check rails and wing rails

within this template.

 

12. 07:45 - 08:10

Put the timbering back (equalized) and store this

template.

 

13. 08:10 - 10:10

Finally we can now shove the timbers on the 1st and

2nd turnouts to fill the gaps we left earlier. Note that

to lengthen timbers at the (numbered) main-side ends,

the Shift key is held down while clicking the "lengthen"

button (or pressing L). (Ditto the "shorten" button).

To save video file size, I left the shoving unfinished.

 

14. 10:10 - 11:00

Finally we can tidy the name labels and reset the

notch out of the view. Notice that the timbering under

each switch and crossing is on the same template as

the corresponding rails. This ensures that the special

chairs are all correctly positioned on the rails.

 

15. That completes this video and we now have a

usable construction template for a 3-way tandem.

 

But there is more to be done for a neat finished result.

The underlying rails need to be removed below all

the V-crossings, and some of the check/wing rails

can be merged by omitting one and extending the

other. This is done by splitting these three templates

into further partial templates, in the usual way.

 

regards,

 

Martin.

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