Customizing the lengths of the Atlas O72 switch

Jan,

I don't believe shortening the switch will help. A Ross#4 with the TR435 sets a 3.5" center. That probably has the ties very close or touching.

The radius and arc angle of the switch turnout is what needs to be changed.  That cannot be changed. The Ross#4 is 14° of a 48" radius for the turnout. The Atlas O72 is 22.5° of a 36" radius. RRT shows a cut O72 turnout to 19.5°. That is probably the limit to shorten the turnout track.

If you have a way to do it by coming off the O72 with flex, the trigger rail can be extended into that new piece for the non-derail. Just place a 1/16th" cut in the rail on the new piece.

The resulting curve from the flex will be near a 15.5" radius to get to a 3.5" center, thus keeping large engines out the yard. Also, trying to flex Atlas that small is almost impossible.

All of that being said, I looked at Ross switches. You could build the 6 track yard setup for about $475 (priced from Nicholas Smith). Sell of some Atlas o72's and the new outlay wouldn't be that bad. This is elegant looking. Fits nicely on the 2' wide table.

Carl's diagram above using Ross #4s is the right choice for you situation.  I would not use 0-72, or any O-XX switch, in a yard if space is tight.  Also, I think the #4s look better.

If you want to use Atlas products, I would go with Atlas' #5 switch although I don't think you will get 6 tracks with a #5 (you might be able to by cutting them down).

Sorry, I failed to stress a very important design issue.  In order to maximize the siding lengths the entrances and exits need to be on the corner curve.  Here is what I put together to date with the inclusion of Carl's idea.

The plans that us straight turnouts.switches are the easiest to implement but result in shorter storage tracks.  I wish Atlas had use a separate short straight with the O72 as they did to the O54. 

Jan

Jan,

Okay,  I understand.  I use Ross #6 curved turnouts in my design (which I'm building now), similar to the one 2nd from top in your diagram.  Here is a way to use cheaper #4 switches.  They can be laid out differently as needed for the space of the 90 degree turn.

Jan,

Like the commercial says, "it changes everything". I see where doubling the switches for a pass-through yards gets to the wiz for new switches.

I say uncle- no matter what I play with, it ends up with only 18' of storage.

Your first combo is the answer, the first Atlas O72 is the second best answer.

Did you notice RRT has an Atlas O72 cut turnout. It appears the diverging tack is cut back close to the guard rails for only 19.5° of arc. They still didn't help. Weird number too.

You stumped me on this one.

I am curious about the Atlas O-72 cut switches in RRT as well. I have 3 older ones and 1 new one, but I can't see what RRT (or Atlas) is doing with them (or how they do it)? I know what Atlas did with the O-54's, they explained that one to me, but I didn't ask about the O-72's? Maybe Steve from Atlas will see this and explain them, he is the one that explained the O-54's to me.

Jan,

I personally would go with the Ross curved switches.  However, I was playing around with #4 switches and O-72 curves and came up with the two yards below.  If your train lengths are different, some shorter and some longer, these give you a couple of pretty long yard tracks at the expense of a couple shorter ones.  Just another option.  You could come up with something similar with Atlas #5 switches.

Jan:

    Several questions

1: how far down the side walls can the yard extend ?

2: are you using flex track?

3: how wide are the corner triangles?

4: are you willing to cut custom pieces of track ?

5: Is the design limited to O-72 curves ?

6: can you use larger curves on the outside track and say O-54 or O-63 on the inside track?

Attached is a design for your review it’s made with standard pieces of MTH Realtrax  O-72 curves and switches (Atlas pieces are the same size) . Using larger curves and or flex track you can could take 6” to 12” off the yard throat.

Galon Tonell

1: how far down the side walls can the yard extend ?

The side walls are 14'.  There is a peninsula in the center of the round the wall loops.  The yard is there.  The aisle between the peninsula and the long side is only 2 feet. 

2: are you using flex track?

I'm using sectional.  Using sectional pieces ensures that I get proper closure of all the loops and all curves are of a know radius.  In the final construction I'll replace multiple short pieces with a single piece.  This minimizes track joint problems.

3: how wide are the corner triangles?

The triangles are 1 foot on a side.  One of the triangles is restricted to its current size. 

4: are you willing to cut custom pieces of track ?

Not a problem with cutting the final pieces.  

5: Is the design limited to O-72 curves ?

O72 is the minimum curve diameter.  My mainlines are O81 and larger.

6: can you use larger curves on the outside track and say O-54 or O-63 on the inside track?

O72 is the minimum diameter.  The designs using Ross curve switches are O72 and larger.  I prefer to use the largest diameter curves that I can.

I am pretty much limited to the examples I posted earlier.

The maximum length that I could trim from the through track is about 3 inches,  That's not enough.  I'm going to have to save up for the Ross curved turnouts.

Jan