Spirals...

andyspencer

andyspencer

Registered
Country flag
United-Kingdom
Evening guys,

So basically I'm looking at the possibilities of putting in a spiral on a new line at on my club track. I want it to look something like the Swiss Brusio spiral, but what radius can I get away with to allow the curve to be more or less continous all the way round? The sorts of trains I wanna run will be swiss RhB 4/4's etc with maybe 6 coaches on the back. But maybe more on a good day. And I'm sure some of us live steam boys will want a stab at the gradient as well with a decent load on the draw bar. Had a search on here, and couldn't seem to find an answer to my radius question...

:)
 
hmm, the biggest radius i know of is the 20ft aristocraft, but i suppose flextrack would be better, allowing you to creat your own "unique" curve..
Hope i helped... :bigsmile:
 
How much room do you have ?
Taking a rough Pi of 3, a ten foot diameter circle will give you a 30 ft run. You need to gain atleast 200mm/8 inches and probably a bit more. 8 inches in 30 ft gives a gradient of 1 in 45 which is probably just about workable with your Swiss stock and 6 coaches.
To do a Brusio style circle you will need to tighten the circle towards one end to bring it inside the main spiral.
ba4b72e8b5684b1ba920a34121920774.jpg
 
Have a look at mine and Dik's vids of his spiral....

http://www.youtube.com/watch?v=nt6qjltT2hA

Single motored locos like a Stainz struggle, large single and double motored locos work much better. Don't have the dimensions to hand, but guess they can be ballparked. Probably something like 3.5m diameter.

Hope that helps.

Malcolm
 
Stockers is on the same wavelength as me on this. With 6 heavy coaches, you must either keep the gradient moderate (say 1 in 50 on a curving track) or go with a heavier gradient and double-head the train. The key factor is the headroom for the crossing point (bridge). I'd go with 200mm PLUS the thickness of the bridge deck. Say 225mm for safety. Raising 225mm at 1 in 50 equals 11.25 metres spiral length = 1.79 metres radius for a purely circular spiral (11.25 = 2Pr where P = Pi = 3.1415 and r=radius). That's 5.9 feet radius. Do the same calculations for 4 feet radius (1.2 metres) and you have a spiral length of 7.54 metres which equates to a 1 in 33.5 gradient which is going to be tough without double-heading. Obviously if you can get away with less headroom (don't forget the bridge deck thickness!) then your gradients get easier.
 
I bought a program from Stans trains, it included a helix calculator in the package. It is one of the best investments I have made. A few entries - track diameter, loop spacing, total rise, grade wanted is real easy with this program. It will then tell you what amount of track & any problems associated with this construction.

Have a look at the sample.
WWW.StansTrains.com
Regards from Andrew
Sandbar & Mudcrab Railway
 
I forgot to add look at the software handy converter for WWW.StansTrains.con
Andrew
 
I made mine with a mix of LGB R3, R5, and a bit of R2. The gradient was about 5% (1 in 20) and there was enough of a height difference at the cross-over to allow a catenary cable to go underneath (just).
overview_2007-08-28_med.jpg


spiral2.jpg


All this has gone now, so I can't give much more detail, sorry.
 
...easy peasey....no complicated mathematical calculations (did take me three attempts to pass "O" level maths:bigsmile:), no surveyors equipment..... just my trusty friend, half-a-bubble on my spirit level.

I've had a go at a Brusio but chickened out of attempting to do the arches on a curved descending viaduct. Here's how it looked at the beginning:
d53844261255402f84ce5b57699fc2e9.jpg


....and how it looked later:
232cb035dfd44b4a8288e8f9d0609e49.jpg


....and how it looks today:
2606fbae50914fdb8f726b9a1dfbad6c.jpg


Still got to finish the rock facing - was hoping to have it finished by now but the somewhat wet summer weather has not been conducive to mixing cement:crying::wits:
 
Have a look (by Googling) at the Raurimu Spiral in NZ north island. It makes the Swiss one look rather puny.
 
I run 5 Rhb bogie cars up in 30, radius 3, with a 2 Buhler motor LGB loco (Re 4/4/II or similar) or 4 cars for those with 2 of the older LGB motors but it is really at the limit of what can be done. At 1 in 20, we are down to 4 bogies. Freight stock is lighter per metre of train length and 24 or 26 axles are possible. Experiment over time suggests that sharpness of curvature is more important in using up tractive effort than steepness of gradient. It is vital to have additional power feeds throughout the gradient - the power draw of some LGB locos (eg the Re 4/4 III) is substantial because of the cab and control lighting - there is also the issue of whether the coaches will have the lighting on, especially restaurant cars.
 
Kent Keith's spiral/loop really looks the biz and has real 'presence'
but.......

Now this is a loop!!!!....or a spiral

For those that may not know...
It is the Tehachapi Loop and allows the trains to climb the impressive gradient.
The train can be seen going over itself at about 2.15 onwards.
The gradient is nearly a constant 2% and was originally built by the Southern Pacific back in the 1870s!.
It is now owned by the Union Pacific who merged the SP. The BNSF have track rights to use it.
Up to 40 trains a day can use the single track.

https://video-lhr3-1.xx.fbcdn.net/hvideo-xtf1/v/t43.1792-2/11386041_10155648873385721_754159199_n.mp4?oh=37343d83e3aeaee576499026b25626c1&oe=557AD159
 
You must log in or register to reply here.
Back
Top Bottom