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Discussion Starter · #1 ·
Hi,

The construction of my elabroate railway stopped for a few months after we descovered that the room was not long enough to allow for a gentle enough gradient to get the trains up onto the top level of the layout. To solve this I have proposed a Helix, but after doing all the maths, my ratio dosn't seem quite right.

Using Pi and a ruler I worked out that one complete circle of 2nd radius equates to 106 inches of track. Is this correct?

The train has to climb about 8-9 inches and I would like to use a gradient of 1:50, as I have heard this is a fairly safe gradient to use. Is that correct?

If I am climbing 8 inches at a 1:50 gradient that is 400 inches of track required. Is *that* correct?

Using all those numbers I worked out that my helix would need 3.7 complete circles to rise 8 inches. Correct?

Im not good at maths, and before I go ahead and start cutting stuff up, I just wanted to check that all of the numbering is correct. Is 1:50 a safe gradient?

Thanks for any help,

Pete.
 

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QUOTE (hoarp001 @ 29 Jun 2007, 01:10) <{POST_SNAPBACK}>Using Pi and a ruler I worked out that one complete circle of 2nd radius equates to 106 inches of track. Is this correct?
Length of circumference = 2 x pi x radius (not diameter)

QUOTE The train has to climb about 8-9 inches and I would like to use a gradient of 1:50, as I have heard this is a fairly safe gradient to use. Is that correct?
That should be perfectly safe but you will probably be able/need to go steeper. I assume you are using H0/OO, but what sort of length trains will you be using? You can test pulling power of a locomotive using track on a plank of wood and adjust the angle.

QUOTE If I am climbing 8 inches at a 1:50 gradient that is 400 inches of track required. Is *that* correct?
To the nearest inch yes. Actual length = square root of (400 x 400 + 8 x 8) = 400.08 inches (2DP)

QUOTE Using all those numbers I worked out that my helix would need 3.7 complete circles to rise 8 inches. Correct?
Yes but here is a problem depending upon how tall your trains are: If you perform 4 circles then clearance between levels in the helix is 2 inches minus - thickness of board used! Unless you use N gauge it will be impossible!

Turns---------Clearance + rail height + wood thickness
4--------------2 inches
3.5------------2.3 inches
3--------------2.7 inches
2.5------------3.2 inches
2--------------4 inches
1.5------------5.3 inches

Whether you can use half turns will depend upon the orientation of the tracks that you are connecting. Using two turns and a gradient of 1:25 sounds a better option with clearance of 4 inches but depends on your trains capability at that angle.

As an N scale modeller I don't know much about OO train power etc.

Hope this helps,
Goedel
 

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Discussion Starter · #6 ·
Ok, so my 106 inch figure was more or less right.

I dont think there will be too much of a problem wth clearence, I am building the helix with threaded rods so i can adjust the height and the clearence of each coil. It dosnt matter if its not exactly 8 inches, the psection of the layout that its building up to hasnt been built yet.

so 1:50 is a safe gradient? Im not likely to have any trains that cant handle that?

Thanks.
 

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Just a word of caution. If testing to find the maximum gradient by using track on a plank as suggested, remember that for a given gradient your locos will haul much less on a curve than on a straight track.

Jerry
 

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Discussion Starter · #8 ·
By that do you mean the pulling power of the loco will be less on a curve, or it will have less load to pull on a curve?

This is for the branch line, and it is primarily going to be there for a BR Class 101 DMU, which is only three carrages so hopefuly, we should be ok..

Thanks for the help.
 

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It will have more load to pull on a curve, but a three car unit should be ok.

Regards

John
 

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Discussion Starter · #11 ·
A buiscuit wouldnt work so well on 6mm MDF. I think i will probably use wood glue and a thin joining plate of very thing modeling plywood... There wont be much pull on it, but we can see what happens, if that fails I will find something else....
 

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Discussion Starter · #12 ·
Hi,

Well I went to homebase and screwfix, and got some bits and afew hours later I had my two discs with the holes and slits cut into it. My calculations went out the window and I just adjusted the deck down so it was about 10mm above the train top, and used that as a mesurement for the whole thing. It came out at 63mm. It does make it up fine, but unless you place the tracks pretty precisely, and pin them down, the front of the cars do come pretty close to the rods, but I think i will get that sorted ok...

They are much easier to make than you would think....
 
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