Layout Underway At Last

[fcwilt]

Originally Posted by DougC

fcwilt:
My suggestion is that while building...

Hope this is helpful.
DougC

Thanks for the input. I know that the track work needs to be as good as I can make it.

Seems to me I have two options as to how to lay the track.

One way would be to lay it one circles worth of track at a time as I install each circle of roadbed into the supports. By doing it circle by circle I wouldn't have to deal with reaching into the limited space between the layers of the helix but I would still be working at the layout in somewhat awkward working conditions.

The other way would be to lay the all of the track on each circle of roadbed at the "workbench" leaving a gap of a inch or two at each end. The next step would be to install each circle into the supports, connecting each circle to the previous with a short piece of track.

Thoughts, please, from any and all - particularly from those who have done this before.

Thanks!

[irocinblue89]

Originally Posted by fcwilt

Thanks for the input. I know that the track work needs to be as good as I can make it.

Seems to me I have two options as to how to lay the track.

One way would be to lay it one circles worth of track at a time as I install each circle of roadbed into the supports. By doing it circle by circle I wouldn't have to deal with reaching into the limited space between the layers of the helix but I would still be working at the layout in somewhat awkward working conditions.

The other way would be to lay the all of the track on each circle of roadbed at the "workbench" leaving a gap of a inch or two at each end. The next step would be to install each circle into the supports, connecting each circle to the previous with a short piece of track.

Thoughts, please, from any and all - particularly from those who have done this before.

Thanks!

fcwilt, What I am doing this time on my helix is to make a full circle of lumber, road bed, and track with feeders then do another full circle on top of that in the same order. Since mine is 77" diameter I figured it would be better to build it in sections. I will leave the last piece of flex track and road bed off untill I have added the the next section of the wood helix. Make sense? It doesn't to me... Check out my thread: http://www.modelrailroadforums.com/f...ad.php?t=29162

[fcwilt]

Originally Posted by irocinblue89

fcwilt, What I am doing this time on my helix is to make a full circle of lumber, road bed, and track with feeders then do another full circle on top of that in the same order. Since mine is 77" diameter I figured it would be better to build it in sections. I will leave the last piece of flex track and road bed off untill I have added the the next section of the wood helix. Make sense? It doesn't to me... Check out my thread: http://www.modelrailroadforums.com/f...ad.php?t=29162

It looks like from one of the pictures you are adding the road bed to the circle of lumber BEFORE you install it into the supports. Is that correct?

I was thinking that if I could install the foam-roadbed/track/wiring at the "workbench" I could do a better job given the improved working conditions.

[irocinblue89]

Originally Posted by fcwilt

It looks like from one of the pictures you are adding the road bed to the circle of lumber BEFORE you install it into the supports. Is that correct?

Yes it is. I am actually installing it all "as I go up". But in order. Wood, roadbed, track, then feeders. Repeat. I feel the same way about building it where I can reach everything better and then locate the helix in it's final resting home.

Seann

[DougC]

fcwilt:

You're welcome.

"Seems to me I have two options as to how to lay the track. "

My response is: Given the high importance of the helix and its maintenance difficulty once installed, I'd suggest you build the helix whichever way that would facilitate the smoothest trackwork - i.e. no kinks, smooth joints, no discrepancies in rail height from one baseboard section to the other, etc. If it takes a little extra time - well, time very well spent (and you and your back will continue to thank you too!)

This thought just occurred to me: If it was mine I would reverse super-elevate the curved track inside the helix. What I mean is, I'd raise the inner rail (not the outer rail) by shimming under the ties. You could experiment with this a little first (I'd use thin cardboard strips and start stacking them) as to what height to raise the inner rail. As long as you're not running trains at break-neck speeds down the helix I'll bet a super elevation (even 1/64 or 1/32nd of an inch) of the inner rail will help a lot.

If anyone has done this track reverse super-elevation please let us know how you fared with downhill and uphill trains, your track radius and grade percent, number of cars in the trains, and anything else that you think is relevant. Thanks.

DougC

[fcwilt]

Originally Posted by DougC

fcwilt:

This thought just occurred to me: If it was mine I would reverse super-elevate the curved track inside the helix.

DougC

Sounds interesting (and curious) but I don't understand why this might be good.

What's the theory?

[DougC]

fcwilt:

Good question.

The physics of reverse super-elevating the helix track is that, when trains are going uphill on a curve there is a lot of pulling force on the head end cars of the train to try to string-line themselves (i.e. the locos pulling on them with the dead weight of all the railcars pulling on them from behind) to derail themselves on the inside of the curve - stringlining).

By raising the inner rail a little the head-end cars will have a harder time string-lining themselves - they have to go uphill some (the inside wheels' flanges have to climb more to get over the inside rail.) Also, with the outer rail now lower than the inside rail the center of gravity of each car moves a little to the outside and it is therefore less likely to derail toward the inside of the curve.

By the way this actually happens on the real railroads from time to time; that's why on mixed freights with a lot of curves on grades the lighter railcars (like empty intermodal cars) are put on the back end of trains. Also, I've string-lined on my own HO model railroad (not on purpose) by starting the train (60 cars) too fast - usually with a jerk from a balky loco - and the first 5 or more cars behind the locos string-line right off the track to the inside of the curve.

And as info, a few weeks ago I saw on railpictures.net a photo of a current BNSF train that string-lined the first 8 cars behind the locos on a crossover track (going from one parallel track to the next) because the engineer didn't wait long enough for the brakes to release on the rear of the train. I bet he was embarrased.

DougC

[fcwilt]

OK I can see when going uphill there might be a benefit but it would seem when going downhill just the reverse might be true.

[irocinblue89]

Originally Posted by fcwilt

OK I can see when going uphill there might be a benefit but it would seem when going downhill just the reverse might be true.

All things equal I would make the track and the wood base as flat as possible perpendicular to the linear run.

[DetroitConrail]

Who made the helix roadbed?