Stations on Curves and Gradients

John Fitton

Stations on Curves and Gradients

Postby John Fitton » Mon Sep 30, 2013 3:51 pm

Layout Planning has generally been my personal nemesis and my fourth P4 layout is no exception. I have redrawn my track plan well into construction and now I have decided it would be nice to have a simple double track station on a 3 foot radius curve, and possibly with part or all of it on a 1 in 48 gradient.

Any views on such a silly scheme would be welcomed.

John Fitton

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jim s-w
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Re: Stations on Curves and Gradients

Postby jim s-w » Mon Sep 30, 2013 9:20 pm

Hi john

3ft radius curve is way too tight. I'd suggest a none scenic 3 foot curve is pushing it but for anything scenic id suggest 6ft radius as an absolute minimum. Also 1 in 48 is very very steep. You might be ok with modern deisels but any sort of train length on that sort of gradient is going to be hard work.

Remember something like a 9ft radius curve should really have check rails and would be something like a 20mph curve.

Hope this helps

Jim


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Re: Stations on Curves and Gradients

Postby Philip Hall » Mon Sep 30, 2013 9:53 pm

I agree with Jim that 3ft radius is too tight, but not by as much as he would suggest. After all, Tim Venton has 3'0" curves at each end of 'Clutton', and by being careful, has achieved success. However, I would say (because I've done it, many times) that it is perfectly possible to build (or convert) virtually any P4 engine to run successfully around a 2'6" radius curve, but I concede it won't look much whilst it's doing it. However, it is mechanically possible, given a decent amount of gauge widening. Something a bit bigger is preferable, so that it will look better.

After years of accepting that I would have to accept 3'6" curves for my new layout, I have recently been presented with an opportunity to consider 4'6" radii for a fairly substantial 'roundy roundy', but even in a (for 4mm scale) big space, 6'0" is just not on; such curves would force me out into the garden!

I would try and increase your curves a little bit if you can as it will make things so much easier, despite what I have said you can get away with. It's not just about what the stock will go around, it's also about gangways between carriages, close coupling of stock to locomotives and all sorts of other things.

Philip

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grovenor-2685
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Re: Stations on Curves and Gradients

Postby grovenor-2685 » Mon Sep 30, 2013 10:39 pm

Despite Jim's views i have steeper grades than 1:48 and can run trains up them, but I would not have a platform on that sort of grade. Unless maybe just a halt for a railbus.
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Keith
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Keith
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Paul Townsend
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Re: Stations on Curves and Gradients

Postby Paul Townsend » Tue Oct 01, 2013 5:28 am

My Highbridge model has its GW platforms on a gradient of 1:40. The up line approach also is 1:40 with 5' radius curve.

Most stock I run copes OK but a couple of locos ( Manors with compensated underbellies) struggle with more than 4 bogie carriages.
The Castle pulls 6 OK which is max for fiddle yard anyway.
The 28xx is OK with 40 4 wheel waggons.

Anything which can get up the hill can restart from the platform when all its train is on the straight 1:40 section.
Rail is NS, wheels mostly NS, some steel.

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Re: Stations on Curves and Gradients

Postby jim s-w » Tue Oct 01, 2013 9:48 am

grovenor-2685 wrote:Despite Jim's views i have steeper grades than 1:48 and can run trains up them, but I would not have a platform on that sort of grade. Unless maybe just a halt for a railbus.
Regards
Keith


Can you expand on that please Keith? I'm thinking I'm going to need a 1 in 50 grade (down and up) for proof house junction and have concerns. What size trains are you talking about? The largest I will need to run is a class 87 (4 driven axles) with 14 coaches but most trains will be somewhere in the 10 coach length).

Certainly with diesels a p4 converted rtr one would go round 1st radius curves (assuming that it did in 00) but it's the couplings that cause problems.

I'm not saying my thoughts are 'the rules' but John asked for our views and that's what I gave him.

Cheers

Jim

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Re: Stations on Curves and Gradients

Postby grovenor-2685 » Tue Oct 01, 2013 10:12 am

Will this be your 87s with Warship drives? If so I'll do a few trials with my Warship, need to check it out first though it seems to have developed a reluctance to run.
How long is your grade? Will the entire train be on it? My grades are closer to 1:25 than 1:50 but not very long so above 6 coaches the whole train will not be on the steepest part hence reducing the average grade for the train.
Keith
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Keith
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Russ Elliott
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Re: Stations on Curves and Gradients

Postby Russ Elliott » Tue Oct 01, 2013 10:56 am

14 pinpointed Bachmanns will require approx 50g drawbar pull to keep them moving on the flat, and up to 50% more on a sharp curve. On a 1:50, the 14 Bachmanns will require an additional (14 x 150)/50 = say 45g drawbar pull to get them up the grade. If the loco is approx 400g, it might have 100g tractive, typically 80g tractive if the suspension isn't great or it's on shiny nickel treads, but it will expend 400/50 = 8g getting itself up the grade. 50+45+8 looks to be on the wrong side of what that 87 might be able to exert. Adding another 100g to the loco weight would make a significant difference.

John Fitton

Re: Stations on Curves and Gradients

Postby John Fitton » Tue Oct 01, 2013 11:47 am

Hello Everyone,

Thanks for your comments, they are appreciated. As you might have suspected the 3 foot radius is constrained by space in my basement. My railway is a folded figure of 8 (I think it's called that) tailchaser and although most of the tight curves are hidden by an upper level or are in tunnels, there is one curve where the scene will be a station. I suppose looking at the bright side the platforms and station clutter will conceal rolling stock overhang and absence of check rails!

The platforms will be about eight feet long - enough for DMUs and short formations. My railway is currently modern image to 1979 so quite a few heavily weighted diesels and electrics, and 12-car trains running on brassmasters or my bogies; all very free running.

I have to hope that there won't be any serious adhesion issues, although I have been quite rigorous in not exceeding the 1:48, even for short lengths. Any tests people have with diesels and passenger cars most welcome.

I have yet to convert any steam locos: I have a couple of easichas kits waiting to be assembled for an A1 and A3. I will ask my son to take some pics; I am somewhat challenged in the arena of digital photography!

Regards and thanks to all.

John

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jim s-w
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Re: Stations on Curves and Gradients

Postby jim s-w » Tue Oct 01, 2013 4:17 pm

grovenor-2685 wrote:Will this be your 87s with Warship drives? If so I'll do a few trials with my Warship, need to check it out first though it seems to have developed a reluctance to run.
How long is your grade? Will the entire train be on it? My grades are closer to 1:25 than 1:50 but not very long so above 6 coaches the whole train will not be on the steepest part hence reducing the average grade for the train.
Keith


Hi All and especially John (I hope you dont mind the distraction)

My class 86 and 87s do weigh just a smidge under half a kilo, The grade is about 6 feet long (although I do have to redraw that bit) and the train will be about 12 and a half feet long in total so thats less than half on the slope (hadnt considered that) - add in that when the train starts to go uphill the other half will be pointing downhill (very little of proof house is flat) I guess the actual train on a hill effect will only ever be 5 or 6 coaches?

Cheers

Jim

John Fitton

Re: Stations on Curves and Gradients

Postby John Fitton » Tue Oct 01, 2013 4:54 pm

Keith and Jim,

My longest grade will be about 16 feet at 1:48, need to get the lower level up top and into the scenic section - a height difference of around 4 inches. I am a great believer in lead weights and load up locos to the limit. I have a Lima Cl 40 weighing in at a full one kilogram!

I am not averse to double heading if necessary. My HST fairly romps around with each power car effectively only pulling four M3 cars.

John

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jim s-w
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Re: Stations on Curves and Gradients

Postby jim s-w » Wed Oct 02, 2013 10:02 am

jf2682 wrote: I suppose looking at the bright side the platforms and station clutter will conceal rolling stock overhang and absence of check rails!

John


Hi john

Why not include them? You could even go the whole hog and included flange lubricators as you can see in the redditch branch platform at Barnt Green.

Cheers

Jim

John Fitton

Re: Stations on Curves and Gradients

Postby John Fitton » Wed Oct 02, 2013 11:00 am

jim s-w wrote:
jf2682 wrote: I suppose looking at the bright side the platforms and station clutter will conceal rolling stock overhang and absence of check rails!

John


Hi john

Why not include them? You could even go the whole hog and included flange lubricators as you can see in the redditch branch platform at Barnt Green.

Cheers

Jim


Jim

Now stop giving me ideas!! All of this has to have OLHE installed as well, BTW

But thanks though.

John

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jim s-w
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Re: Stations on Curves and Gradients

Postby jim s-w » Wed Oct 02, 2013 12:01 pm

It's even more like barnt green then. Overhead on tight curves is going to be awkward. You are going to need an awful lot more masts. I'll work out the spacing on a 3ft curve for you.

John Fitton

Re: Stations on Curves and Gradients

Postby John Fitton » Wed Oct 02, 2013 2:51 pm

jim s-w wrote:It's even more like barnt green then. Overhead on tight curves is going to be awkward. You are going to need an awful lot more masts. I'll work out the spacing on a 3ft curve for you.


Jim,

As I am about to embark on my first piece of sceniced railway since I was 13 (and that was all my dad's work anyway!) and OHLE is a feature, maybe we should transfer the OHLE discussion to another topic? and; how the heck do I do that? Help, Keith!!

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Re: Stations on Curves and Gradients

Postby jim s-w » Wed Oct 02, 2013 4:22 pm

Hiya

See viewtopic.php?f=14&t=2979 for more on the mast spacing

Cheers

Jim

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grovenor-2685
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Re: Stations on Curves and Gradients

Postby grovenor-2685 » Sat Oct 05, 2013 9:32 pm

Managed to check over the Warship, all it needed was a good wheel clean after sitting around out of use for almost two years, running well after cleaning so I have given it a good run around. On my main line with an upgrade that probably averages 3% over a train length and reaches 4% in the middle it has no trouble with 9 coaches. I would expect several more on Jim's proposed 2%. The grade out of my bottom storage track measures out at 6% over the middle section, maybe 5 coaches worth and then has longish vertical curves each end, and fairly tight horizontal ones too. (It was an afterthought and a bit of a shoehorn job!). The Warship just manages 6 coaches out of here, seven defeated it. Not a problem for me as the sidings only hold loco + six anyway. For comparison 6% is the same as the DLR climbing out of Bank, or the Hopton incline on the C&HP.
We need at least 30% motored bogies out of Bank, ie a good unit can pull one dead one, and the tank locos on the C&HP could take about 4 wagons and brake van up Hopton, so the Warship does fairly well.
Regards
Keith
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Keith
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jim s-w
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Re: Stations on Curves and Gradients

Postby jim s-w » Sun Oct 06, 2013 1:52 pm

Thanks for that Keith

Much appreciated

Jim

John Fitton

Re: Stations on Curves and Gradients

Postby John Fitton » Sun Oct 06, 2013 8:58 pm

Thanks for that Keith for me too. So for running 12-car trains I think the modern diesel and electric models should be ok, and I will have to take my chances for my as yet unconverted steam locos.....

With a simple re-plan my station is now almost on level track, but still 3 foot radius.


John


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