Maximum gradient

[roger440]

Im continuing to ponder my layout design ideas. (which is all i can do until i build the railway room)

 

Any views on what is a realistic maximum gradient and curve radius that can be combined and still run 10 coach trains? Layout would be all diesel.

 

Any such curves would not be on a scenic section. I had been working on a 30-36 inch minimum radius?

 

ive never had any gradients on any of my previous layouts.

[gordon s]

There is a lot on information on here re gradients and I do recall seeing a chart that gave a recommended gradient based on the type of loco, no of coaches and radius of a curve, but blowed if I can find it. Traction from diesels is generally much better than steam locos, but 10 coaches is quite a weight to pull, particularly around a curve. Personally I wouldn't go below 1:50, but others may see things differently.

[Kris]

You will find that a lot will come down to the loco and how free running your coaches are, coach weight will also play a part. I suspect that 2% (1 in 50) would be around your maximum. I would suggest that you get a 2 - 3 meter long plank and add a strip of track to it. You can then trial to find the optimum gradient. Once you have found this on the straight adjust it downwards a little to give some leeway for your curve.

[HLT 0109]

Gordon is right, there has been a lot about this on this forum in the last twelve months, some of which I have been involved in. Some may remember that I have gradients of 1:15 and 1:20 with 2nd and 3rd radius curves so what you are suggesting, Roger440, is somewhat kinder to locos than mine. In light of my experience, I would suggest that Gordon's recommendation is still quite steep for the proposed length of train but you may succeed. It appears that each loco has different, uphill pulling power and it is not entirely predictable. My Bachmann class 55 will not haul as many coaches up my incline as my Bachmann class 47 and my Bachmann class 37 hauls fewer than my Bachmann class 25. That is the opposite of what I expected considering the different weights of the locos and the fact that the class 25 has only four driving axles. Also, I find that my incline puts quite a strain on the couplings, especially the one on the loco. 1:50 or better will put less of a strain on these items. A most important consideration is the transition from level - make it as gradual as possible and keep it straight if possible. On my extreme example, I find that long coaches detach from the loco and sometimes from each other because the knuckles of the Kadees slide off one another as the loco levels and the coach is still on a steep part; then I have to catch the coaches! My remedy is to put a short parcels wagon immediately behind the loco.

[bigherb]

You also have to considered the length of the gradient, would all the train would be on the gradient at one time?

[roger440]

There is indeed more info on here. I altered my search to helix and much was found!

 

Problem is i dont/cant limit the gradient to certain stock. Everything that runs will need to climb it. And that includes 10 coach rakes, HST's etc.

 

Im now thinking the climb should be straight with the curves only downhill. Not sure i can achieve that. More plans need to be sketched!

[roger440]

You also have to considered the length of the gradient, would all the train would be on the gradient at one time?

 

Yes, probably. Trying to get a fiddle yard under a scenic section somehow.

[Allegheny1600]

Hi there,

Several things to consider here!

In addition to a gradual transition from level track to inclined, you also need to make any transition from straight to curved as gently as possible - this will guide your rolling stock and give your locos the best chance possible.

How many degrees of curvature do you need on the gradient? If you can find a way of reducing this, so much the better!

You want a scenic section over the fiddle yard? With track on the scenic, I take it? How about both lines being on a grade i.e. down to the fiddle and up to the scenic, rather than all down to the fiddle or vice-versa (unless you're already doing that?!!).

Finally, plan to keep all track and all rolling stock wheels really, really clean as it's surprising just how much friction a dirty wheel can give!

Finally, finally(!) allow for some lighting over the fiddle tracks and also some finger/hand room - as you will always need access under there!

Cheers,

John E.

 

PS my current layout has a fluctuating or uneven gradient of around 1 in 40 overall with a gradually tightening curve, initially around 6' radius down to around 4' (then to 18" radius on the level!) and most modern British diesel locos can take 10 coaches quite comfortably, full length HST is fine, even a 36 wagon MGR!

HTH.

[34theletterbetweenB&D]

Definitely trial the actual train formations you plan to operate. Something else to think about and test; will trains ever have to start from rest while standing partly or wholly on the gradient? Especially if the gradient is concealed or needs some effort to access, reliable restarting may set a limit on the gradient you can use.

[roger440]

Hi there,

Several things to consider here!

In addition to a gradual transition from level track to inclined, you also need to make any transition from straight to curved as gently as possible - this will guide your rolling stock and give your locos the best chance possible.

How many degrees of curvature do you need on the gradient? If you can find a way of reducing this, so much the better!

You want a scenic section over the fiddle yard? With track on the scenic, I take it? How about both lines being on a grade i.e. down to the fiddle and up to the scenic, rather than all down to the fiddle or vice-versa (unless you're already doing that?!!).

Finally, plan to keep all track and all rolling stock wheels really, really clean as it's surprising just how much friction a dirty wheel can give!

Finally, finally(!) allow for some lighting over the fiddle tracks and also some finger/hand room - as you will always need access under there!

Cheers,

John E.

 

PS my current layout has a fluctuating or uneven gradient of around 1 in 40 overall with a gradually tightening curve, initially around 6' radius down to around 4' (then to 18" radius on the level!) and most modern British diesel locos can take 10 coaches quite comfortably, full length HST is fine, even a 36 wagon MGR!

HTH.

 

Yes, the idea was to put the yard underneath the scenic section. So the line would come off the scenic section and round a 270 degree-ish curve, then a 90 the other way to arrive under the scenic section, with a miiror image at the other end. Having looked at the drop required in order to be able to access the yard as you suggest, this isn't achievalbe unless i go to a helix, though the question remains the same. With an outer diameter for the helix of 7ft, the gradient doesn't look quites so bad , but the WHOLE train would then be on the curve which is my concern.

 

I dont quite follow your suggestion of both lines being on a gradient? The scenic area would have to be flat as there would be times when no loceo is attached to the rolling stock. Effectively it would be a double track roundy roundy.

 

Interesting about your layout, mainly because i seriously considered buying it, hence the questions ref its stored size Sadly it not quite what i want, but mainly, its simply to wide for the space i have without major building surgery.

[Allegheny1600]

Hi Roger,

Aah righto! That was you! Thanks for your interest and sorry it's not quite right for you, I have the same problem!

What I was saying about both lines - I thought along the lines of you starting your whole layout as flat boards all the way around your room, with a gradient up to the scenery and thought, if you could drop the fiddle yard, you'd effectively double the amount of track on grade, thereby halving the grade. I (think!) I follow what you want to do now, is it all flat scenic on top of all (flat) fiddle in a sort of dogbone - not round the room?

Helixes, eh?

This is what I've got to design for the new US layout! I'm looking at a 6' diameter helix, so 1 turn gives approximately 18'9" circumference (216 inches!). I need to climb four inches between levels so 216/4 is 54 or 1 in 54! I will be happy with that but I suggest that using British stock, you will only need to climb 3 inches between levels. So, 216/3 is 72 (1 in 72).

So you should be able to either; be very comfortable with 6' diameter helix, drop the diameter and increase the grade back to c.1 in 50/55 (4'6" diameter gives 1 in 56!) or keep the 6' diameter and drop 4"!

A point to bear in mind though is that, as you increase the tightness of the curves, you also increase the friction on the wheels. So, while it may be possible to go tighter, I would stick with 6' minimum! If you wish to use the full 7' - even better as your gradient goes down and your friction due to the curve also goes down (win, win!).

Sorry for rambling on but this is a subject I am very interested in both in model and prototype terms!

I also have to remember that British locos are not as powerful as US models and UK rolling stock is not generally as free running! I'm looking at running up to 40 bogie hoppers up my helixes!

Cheers,

John E.

[Allegheny1600]

Yes, the idea was to put the yard underneath the scenic section. So the line would come off the scenic section and round a 270 degree-ish curve, then a 90 the other way to arrive under the scenic section, with a miiror image at the other end. Having looked at the drop required in order to be able to access the yard as you suggest, this isn't achievalbe unless i go to a helix, though the question remains the same. With an outer diameter for the helix of 7ft, the gradient doesn't look quites so bad , but the WHOLE train would then be on the curve which is my concern.

 

Sorry Roger,

I'm not sure I answered your query here.

I'm positive that if you go for a 7' diameter helix (264"/3" = 1 in 88!) or (264"/4" = 1 in 66!) you will be absolutely fine with the whole train on the helix. You'd have to run a train longer than 22 feet to exceed just one turn and I'd suggest you probably want at least three turns or more to gain sufficient clearance in the fiddle yard. I'm sure that most British stock will cope with a gradient and curvature like that without any problems!

Cheers,

John E.

[Kris]

Roger, I would agree with John in the suggestion that if you went for the 7ft helix you would have no problems with scale length trains. If you did then that loco needs looking at.

[Wummyock]

On the subject of helix's as that is what I have planned for next year,I was considering using 3rd and 4th radius curves(Peco) what sort of haulage should I expect working on 3" rise/lap?Or more to the point will I be able to run prototypical length trains running diesels?

[gordon s]

3rd radius is 19.875" radius which equals 39.75" diameter. To find the circumference, multiply the diameter by pi (3.142). This will give a circumference of 124.89". A rise of 3" would therefore be a gradient of 124.89/3 = 1:41.6.

 

On the face of it not bad, but the drag of trains on a curve that tight would have the effect of increasing that gradient considerably, probably 1:30 or lower. Another possible problem is that you may get string lining. This is where the coaches or wagons will try to go in a straight line and the loco will simply pull the coaches off the track.

[roger440]

Hi Roger,

Aah righto! That was you! Thanks for your interest and sorry it's not quite right for you, I have the same problem!

What I was saying about both lines - I thought along the lines of you starting your whole layout as flat boards all the way around your room, with a gradient up to the scenery and thought, if you could drop the fiddle yard, you'd effectively double the amount of track on grade, thereby halving the grade. I (think!) I follow what you want to do now, is it all flat scenic on top of all (flat) fiddle in a sort of dogbone - not round the room?

Helixes, eh?

This is what I've got to design for the new US layout! I'm looking at a 6' diameter helix, so 1 turn gives approximately 18'9" circumference (216 inches!). I need to climb four inches between levels so 216/4 is 54 or 1 in 54! I will be happy with that but I suggest that using British stock, you will only need to climb 3 inches between levels. So, 216/3 is 72 (1 in 72).

So you should be able to either; be very comfortable with 6' diameter helix, drop the diameter and increase the grade back to c.1 in 50/55 (4'6" diameter gives 1 in 56!) or keep the 6' diameter and drop 4"!

A point to bear in mind though is that, as you increase the tightness of the curves, you also increase the friction on the wheels. So, while it may be possible to go tighter, I would stick with 6' minimum! If you wish to use the full 7' - even better as your gradient goes down and your friction due to the curve also goes down (win, win!).

Sorry for rambling on but this is a subject I am very interested in both in model and prototype terms!

I also have to remember that British locos are not as powerful as US models and UK rolling stock is not generally as free running! I'm looking at running up to 40 bogie hoppers up my helixes!

Cheers,

John E.

 

You ramble away! All info is good.

 

Yes, you have assumed correctly, it would be a "dogbone" arrangement. The room is less than 8 ft wide, so a scenic section one side (quite wide if my fixation with Reading Station continues) and a decent sized fiddle yard the other side of the room would make for quite a cramped affair for the operarator(s).

 

Im warming to the helix idea right now!

 

Sorry Roger,

I'm not sure I answered your query here.

I'm positive that if you go for a 7' diameter helix (264"/3" = 1 in 88!) or (264"/4" = 1 in 66!) you will be absolutely fine with the whole train on the helix. You'd have to run a train longer than 22 feet to exceed just one turn and I'd suggest you probably want at least three turns or more to gain sufficient clearance in the fiddle yard. I'm sure that most British stock will cope with a gradient and curvature like that without any problems!

Cheers,

John E.

 

Thats encouraging. if i did Reading station i did occasionally see 16 van parcels trains as well as the stone trains during the late 80's. Ok, i can shorten them a bit, but not too much hence my concern

 

Roger, I would agree with John in the suggestion that if you went for the 7ft helix you would have no problems with scale length trains. If you did then that loco needs looking at.

 

Again encouraging. Any ideas about propelling. HSTs will need to do this.

[Wummyock]

3rd radius is 19.875" radius which equals 39.75" diameter. To find the circumference, multiply the diameter by pi (3.142). This will give a circumference of 124.89". A rise of 3" would therefore be a gradient of 124.89/3 = 1:41.6.

 

On the face of it not bad, but the drag of trains on a curve that tight would have the effect of increasing that gradient considerably, probably 1:30 or lower. Another possible problem is that you may get string lining. This is where the coaches or wagons will try to go in a straight line and the loco will simply pull the coaches off the track.

 

 

I just done the calculations for 4th and 3rd rad curves Gordon and got 1 in 47 for 4th rad(572mm) and 1 in 46 for 3rd(505mm) rad that was going to 3.14 as pi and doing the sums in mm's.Must admit Im a tad concerned about this string lining you talk of!Dont fancy seeing my money career off into the centre of a helix lol.I know its simple to set up a straight gradient for testing but its blooming hard to set up a helix short of constructing it.

[Wummyock]

What sort of gap between levels were you looking at Roger440?

[roger440]

What sort of gap between levels were you looking at Roger440?

 

For something like a 12-16 road yard, id guess that you would want 10-12 inches minimum.

[HLT 0109]

This topic is again becoming very technical with details of radii and the effects of friction on the curves etc. This all good stuff but there is no substitute for experience and I would repeat two things I have said before: (1) there used to be a website "Camelot Junction" on which the creator used a helix of 4' diameter with 7" between layers and easily ran diesel trains up it. I think that incline worked out at 1:25 or thereabouts; (2) My extreme incline of 1:20 negotiates two curves of 3rd radius which do not appear to cause the trains to slow down and leads into a straight on a 1:15. My class 47 hauls six coaches up the incline and will restart on the 1:15. This leads me to believe that Roger440 would have no problem with his proposal, although I do not think he has stated the length of the incline. His propasal sounds very much like mine - a fiddle yard below the scenic section - and my incline runs for about 25' from one level to the other giving me 17" of headroom at the bottom. A question I would ask is, why is it necessary to haul all coaches up at once? Would not additional operational interest be achieved by one loco assembling a train on the scenic section for the express?

[Wummyock]

For something like a 12-16 road yard, id guess that you would want 10-12 inches minimum.

 

 

I was thinking of 15-18 myself as I wanted to have scenery on the lower deck away from the fiddle yard,the only thing that may change that was I was thinking about a second fiddle yard as a supposed terminus/dock yard.So it may well be nearer your guess so I would only have a 20-24" gap between the 2 main levels.Having got the Model Railroader book on multi level layouts they seem to have minimal distances between main levels and staging/fiddle yards.

[roger440]

This topic is again becoming very technical with details of radii and the effects of friction on the curves etc. This all good stuff but there is no substitute for experience and I would repeat two things I have said before: (1) there used to be a website "Camelot Junction" on which the creator used a helix of 4' diameter with 7" between layers and easily ran diesel trains up it. I think that incline worked out at 1:25 or thereabouts; (2) My extreme incline of 1:20 negotiates two curves of 3rd radius which do not appear to cause the trains to slow down and leads into a straight on a 1:15. My class 47 hauls six coaches up the incline and will restart on the 1:15. This leads me to believe that Roger440 would have no problem with his proposal, although I do not think he has stated the length of the incline. His propasal sounds very much like mine - a fiddle yard below the scenic section - and my incline runs for about 25' from one level to the other giving me 17" of headroom at the bottom. A question I would ask is, why is it necessary to haul all coaches up at once? Would not additional operational interest be achieved by one loco assembling a train on the scenic section for the express?

 

Its likely (maybe) that it would be a model of Reading station, so train lengths are what they are. The operational aspects are dictated by what happened in real lfe. The "dogbone idea appeals as it gives the operator(s) more space, and depending exactly how i do it, may allow viewing from both sides.

 

6 coaches on 1:20 sounds good, but what if it was 16 bogie vans? Im guessing its not going to happen. Ive got a long space to work with so scale length trains are not a problem.

[roger440]

I was thinking of 15-18 myself as I wanted to have scenery on the lower deck away from the fiddle yard,the only thing that may change that was I was thinking about a second fiddle yard as a supposed terminus/dock yard.So it may well be nearer your guess so I would only have a 20-24" gap between the 2 main levels.Having got the Model Railroader book on multi level layouts they seem to have minimal distances between main levels and staging/fiddle yards.

 

id agree 15" - 18" would be far more desirable than 10". I have no need for scenery on the lower level, however. But a 18" drop is a lot.

[Wummyock]

Roger have a look at exeterstandrews.web.com it has a helix on it.

[roger440]

Roger have a look at exeterstandrews.web.com it has a helix on it.

 

Intertesting. Shame there is no track plan

 

The more ideas i see, the more indecisive i become!