helix

[STEAMON DEMON]

FIRST FORMAL LAYOUT. I am planning an HO 18" radius helix with a 3% grade (2.5" vert. clearance - not NMRA standards for vertical clearance) but I am running 30-34' short cars & locos, (Bachman Shay or Riv. Heisler) - roadbed is (2) laminated 1/8" hardboard reinforced with Aramid fiber at the bottom to reduce deflection (300,000 psi as I recall). Feel free to call me crazy at this point before construction begins as I tend to push the engineering limits due to space constraints.

[Ronson2k3]

You can really use what ever you like as a roadbed so long as you have support to hold it. If you are building a helix / Grade you will need to be able to deflect it though. With a helix that brings about a different problem. You may want to adjust the helix as rotation places extra forces on the climb besides just the grade itself. The rail as well will need to accept the grade you are giving it. You may need to create an easement? As you are running Shay or Heisler small wheelbase loco's. The real ones had high torque but aren't very fast. So your train could be in the helix for a while.

My layout is going to require Two helix's. I'm going 3 operating and 1 staging.

In your case I would experiment to see what grade/number or turns you can run. Then how long it will take your train to complete the trip between levels. Build one turn with hardboard complete with track. Run it from a flat surface then you should be able to get all the data you need to run the trains you want to run on the layout.

The grade you can run then reduce that a bit just to be safe then the number laps (rotations) you will need to run. Then with the time it takes to run that turn x the number of turns to get to the next level you want to run at. The time it takes to run through that turn will also tell you how long it will take to get to your next level as well.

http://webpages.charter.net/dobbsp/mrr.htm

A really good helix calculator plus other useful calculation/conversions in the same software.

Remember it's not just what you want to do it's what your locomotive/train is capable of doing you need to consider. Once you build it you will be stuck with the grade you have created so it's a good idea to make sure your trains are able to run that grade.

As you are running a logging operation there are other ways to get to the next level you may want to consider. Such as a switch back if your railroad is located near mountainous area. You may also be able to add more power to your train to make it over/through the grade. It wasn't uncommon to have more then one locomotive on logging trains but it's up to you. If you find your grade requires it you can try reducing the grade to get around that if one locomotive is what you want to run. All that is possible on a Helix Test run..

Hope that helps.
Ron

[Bill Nelson]

If you go with an 18 inch radius and a 3% grade you are not going to be able to get much up it with a Bachman Shay. on my RR's Valley division I have a 3.3% grade, which my Bachman Shay can get six or seven cars up. That grade has 22 inch radius curves on it. As the radius goes down, the drag on the locomotives and cars goes way up. at my club, where my Bachman Shay has gone to live on a branch with slightly more than 18 inch radius curves and a grade appoaching 4.3% the Bachman shay can handle only a meager 3 or 4 cars. it every extra inch of radius on your helix will help you out 3 times. 1. longer run to gain height = lesser grade needed. 2. longer distances between overlaping tracks= more overhead clearance and 3 drastically reduced rolling resistance on locomotives and equipment.

The only places on my extensice layout where the Bachman Shay was happy has Curves of more than 20 inch radius, and low grades . were I to design a layout with the Bachman Shay in mind I would have a minimum of 20 inch radius, with a 22 inch radius greatly preferred, and grades no more than 2% preferably 1.5% My Bachman Shay has gone to the club, as it shares the only section of track on my home RR it is happy with with a PFM 3 truck shay which will not negotiate the sharper curves elsewhere on my RR. The PFM Shay, with new motor and NWSL gear reduction can pull more than twice the Bachman. At the club, my Bachman Shay may end up as a switcher at the big coal mine I am planning, because it is a weakling when it comes to pulling the hills.


The Bachman Shay is a fine looking and ok running machine, but it is way to weak to suit me. I have two Westside class A climaxs that can outpull a Bachman shay on 18 inch radiuss of any grade, which is silly, since the Shay is three times loner the the class a climax, and has an extra power truck!


My two cents worth


Bill Nelson