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Author Topic: Planning an incline.  (Read 1835 times)

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Offline Jerry Howlett

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Re: Planning an incline.
« Reply #15 on: November 05, 2017, 02:48:00 PM »
Union Mills are the "supermen" of N Gauge.
Some days its just not worth gnawing through the straps.

Offline Webbo

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Re: Planning an incline.
« Reply #16 on: November 06, 2017, 07:25:43 AM »
I'm curious about the notion that it is harder to pull stuff around a curve (on an incline or not). I've accepted this, but decided to have a closer think about whether this is really true. On examination, my physics says that it is should not be so. When considering this, think of what happens when you push a free-rolling carriage round a curved piece of track - no slowdown. Think also, of the rim of a wheel. What will slow it down when rotating is the friction in the bearing not the fact that the mass on the rim has to continuously go round a curve.

To be sure, rolling stock being pulled around a tight curve is more likely to derail, but this is not an issue of increased traction being required on curves.

Webbo

Offline Bealman

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Re: Planning an incline.
« Reply #17 on: November 06, 2017, 07:54:15 AM »
Interesting! I agree with your post, but stock will definitely derail on curved inclines. I know this as I lost a lightweight Poole carriage onto the concrete floor.

Mind you, it was SR green, so no great loss  ;D ;)
Vision over visibility. Bono, U2.

Online Chris Morris

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Re: Planning an incline.
« Reply #18 on: November 06, 2017, 08:23:05 AM »
My videos above tend to back up what Webbo has said. Tight curves and long trains don't seem to create slipping issues whereas fairly reasonable gradients often do even with the latest stock.

I think curves on inclines will show up any imperfections in track laying more than level curves or straight inclines will. I was surprised to find I could put a banker on the back of my train of 20 four wheel vans and it would go round and round my undulating layout with any problem.

Offline Bealman

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Re: Planning an incline.
« Reply #19 on: November 06, 2017, 08:41:38 AM »
Cool.

I think I just got shirty about losing a coach.

Anyway, Hills & Meadows completly nullifies my whinge. :beers:
Vision over visibility. Bono, U2.

Online railsquid

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Re: Planning an incline.
« Reply #20 on: November 06, 2017, 12:21:34 PM »
I too have a partially curved incline, and have done a fair bit of testing with a variety of stock to make sure it's fit for purpose. I can't recall what the exact gradient is (probably about 3.5%) which is just about the limit for the British trains I intend to run, most locos will haul 5 "Blue Ribands" up just fine (including, to my surprise, the modern 08 version, and even the Dapol 14xx manages one autocoach). Most of my non-British stock runs up it like it's not really there, of course.

The curved section is 180deg of 280mm radius Tomix track, I do recall there were derailments with certain trains - I forget which but they were prone to derailing anyway, and it also doesn't help that the track is not all that well supported at the moment.

I do recall experimenting early on in my N gauge days with a gradient consisting of a straight section then a curve; the British locos seemed much happier once they hit the curve, I suspect that gave the bogies a better "grip" for want of a better word. I also suspect shiny new track and shiny new  locomotive wheels, as they were at the time, didn't help.

I can also well imagine that if the curves meander about a bit and are uneven across the width of the track that derailments and/or traction loss would be likely.
Takahachikawa - Japanese and other trains

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Offline Old Crow

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Re: Planning an incline.
« Reply #21 on: November 06, 2017, 01:38:51 PM »
Having experimented with set-track curves 10.5 radius on the flat, my stuff will go round at well over 70mph no problem! But I did find that any banking of the track - and vertical movement - as it wasn't fixed down - did give occasional problems with electrical conductivity. Still mulling it over; I think I can get a run of around nine feet to get 50mm with a very gentle rise on the curved area.
When I've got the board finished I'll do a trial with a straight length of track on a board to see what inclines I can get working. My locos are old ones with some weight in them; in particular, the Duchesses seem to be good pullers and for a test load, I'll start small but build up to a rake of old Lima coaches that have steel plated in them.

Offline Intercity

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Re: Planning an incline.
« Reply #22 on: November 06, 2017, 02:59:59 PM »
Having read through this with interest as I plan on 2 inclines (one in a kind of s curve and the other in a constant curve) it seems that none of it is recommended, are the problems transitioning from an incline to a curve without banking?

If curves give so many problems why are helix towers so popular?

Have people managed to successfully create inclines that curve and if so what limitations are there (I also see limits on what can pull a full consist but thatís what the low and slow lines are for)
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Offline Newportnobby

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Re: Planning an incline.
« Reply #23 on: November 06, 2017, 03:18:09 PM »
The main factors in inclines with curves are (a) the gradient, (b) the radius of the curve and (c) what you intend to run up/down the incline.
Regarding (a) the recommended minimum is probably 2%.
The main experts on this forum regarding helices are @Maurits71 and @Michiel so maybe they could advise what radius curves they used.
Maurits uses mainly big diesels/DMUs and Michiel uses non UK stock so maybe they have better haulage capacity than the average UK steam loco, which are the ones likely to cause you issues.
I don't have any inclines on my layout but my Dapol class 35s still struggle to haul what I would call a prototypical load

Online njee20

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Re: Planning an incline.
« Reply #24 on: November 06, 2017, 03:23:45 PM »
Have people managed to successfully create inclines that curve and if so what limitations are there (I also see limits on what can pull a full consist but thatís what the low and slow lines are for)

I have a roughly 2% gradient that curves about 120 degrees on a c18" radius curve. The only locos that will pull a truly 'full' modern consist (ie 36 two-axle wagons, 21 bogie hoppers or 30+ intermodal flats) are Farish 60s. Farish 66s aren't far behind, Dapol 66s lag further behind. Other things (Farish Voyagers and 350s) can barely manage their own weight. I keep shorter trains on the upper levels. I don't think the curve drastically impacts anything frankly.

Online Chris Morris

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Re: Planning an incline.
« Reply #25 on: November 06, 2017, 04:48:46 PM »
I'm quite happy with my Hymek, she will pull 24 vans up a 2% grade with a curve.

Online railsquid

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Re: Planning an incline.
« Reply #26 on: November 06, 2017, 05:15:20 PM »
At this point I think we can conclude that curves on a gradient are not a bad thing per-se.

In the interest of scientific experiment, and also because it's a good excuse to run trains, I've spent a bit of time running an ad-hoc 9 coach rake (mix of Japanese, German and British stock which were at hand, real citizen of nowhere that's me) up and down my incline (described earlier). The nasty part is, the curves are settrack currently supported in a very ad-hoc way, with some of the joints actually suspended in mid-air (don't try this with Peco settrack ;) ), and the last section gets suddenly steeper as the locomotive's weight is pressing down on the joint (which is something I'll fix when I get round to it).

Basically anything with traction tyres will haul that 9 coach rake up the gradient with at most a slight slowdown at the steep/unstable section at the top. So basically any non-UK outline stock, and my Lima 86 and Minitrix 47 - both fitted with traction tyres. However a Dapol 58, which is basically a good hauler, didn't get beyond the steep/unstable section. Which is about as far as my ancient Poole 47 got. Remove 3 coaches and the British locos are fine, which is about what I'd designed it for. If I wanted to e.g. pull 10 coach rakes with British kettles I'd need a lot more space anyway, and if I had the space I could make the incline gentler.
Takahachikawa - Japanese and other trains

Birmingham Knotmore Street - (ex) GWR mainline through the Midlands

Online railsquid

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Re: Planning an incline.
« Reply #27 on: November 06, 2017, 05:20:31 PM »
Additional data point: I don't have many British kettles, the nearest one at hand is a Farish Duchess 4-6-2 with traction tyres, it doesn't really like the transition from straight to curve on the gradient (I suspect because it's one of the parts floating in the air), but otherwise just about manages the 9 coaches without too much drama.
Takahachikawa - Japanese and other trains

Birmingham Knotmore Street - (ex) GWR mainline through the Midlands

Online njee20

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Re: Planning an incline.
« Reply #28 on: November 06, 2017, 05:28:34 PM »
I'm now wanting to go home and try all my different stuff to remind myself, purely in the name of science! Only foreign thing I've got is a Kato Eurostar, which based on others' reviews will romp up there at warp factor 10 whilst dragging all my other stock.

Edit: I tried, yes, a 2+12 Eurostar went up with nary a hint of trouble.
« Last Edit: November 06, 2017, 08:35:00 PM by njee20 »

Offline Yet_Another

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Re: Planning an incline.
« Reply #29 on: November 06, 2017, 08:02:40 PM »
Actually, the problem with all curves, whether they're on an incline or not, is friction, as referred in this article:

http://uic.org/cdrom/2008/11_wcrr2008/pdf/S.2.2.4.1.pdf  (obtained with a quick google)

When negotiating curves, the wheels have a tendency to move out of the perfect alignment, and the flanges scrape along the side of the rail. As the speed of the inner and outer wheels need to be different (different radii of inner and outer rails, but fixed axles), there is a slippage effect also.

As more power is required to go up a gradient, even more power will be required if there is a curve on that gradient.

The drawstring effect is also enhanced on gradients, as the force at the coupling is greater, just because gravity is also pulling on the wagons, not just the inertia and enhanced friction.
Tony

'...things are not done by those who sit down to count the cost of every thought and act.' - Sir Daniel Gooch of IKB

 

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