Gradients

[1867Adelphi]

Hi everyone.
I've found a model railway gradient calculator - https://www.modelbuildings.org/track-grade-calculator/ to use for my car port / garage layout.

I'll have two slopes. 
The first is on layout level rising 90mm to an upper level and I'm going to have that at about 2-3% to keep it realistic - no problem.
My second gradient (and the one I want to ask the question about) will take the take down to my fiddle yard which I want underneath the main layout to give me more layout space on top.

What is the absolute max percentage of gradient locos can get away with?
This doesn't mean I'll go to the max but I'll have an idea for where to stop!!

The slope to the fiddle yard will be underneath the "upper level" so out of sight.
I'm going to use DCC, mainly newer locos. Rakes will generally consist of no more than 6 or 7 coaches for passenger trains and I don't have a large quantity of rolling stock (yet) so no huge rakes of wagons.
I'll also make use of the DC Concepts Powerbase to help with things.

The more grade I can get away with, the lower I can get the fiddle yard down and have more space to get at things.

Hope anyone can pass on their advice.
Mike

Edited June 19, 2021 by 1867Adelphi

[Dungrange]

That's very much locomotive and stock dependent.  Diesel locomotives can typically haul trains up gradients better than some steam locomotives, so the era you are modelling is relevant.  However, that's only a generalisation.  Also, how free running your rolling stock is will influence whether a particular locomotive can pull a particular rake of coaches or wagons up the incline.

 

In general, I'd say a 2% gradient is a desirable target and 3% is the maximum I would consider, but remember that you will need to allow transitions between level and gradient at the top and bottom of your incline, so it's a little more complicated than that simplistic calculator implies.  If you've taken the 'run' to be the total distance that you have available for your incline, and then you transition into and out if it, that calculator will give you the average incline, but the maximum will be greater.

[Kris]

I would take 3% as a maximum.

[Harlequin]

Covered fiddle yards, hidden gradients, powerbase… In my book those are all things to avoid if you possibly can!
 

Would you like to share your track plan with us? We might be able to offer some helpful suggestions.

 

[ITG]

I found that what I thought was 3% actually wasn’t. Why? Well, my baseboard wasn’t absolutely level which added an additional gradient %, and also the calculated distance at 3% didn’t allow for the transition from 0% to 3%, meaning there was a short section which was a “shock” to some locos. Some locos were ok, mainly diesels. Hence new layout was based on 2%.

[Siberian Snooper]

Curves will also be a factor in the load a loco can haul up a gradient, the tighter the curve, the flatter the gradient will need to be. I would suggest you do some trials to see what will work for you.

 

 

[ISW]

14 hours ago, 1867Adelphi said:

The more grade I can get away with, the lower I can get the fiddle yard down and have more space to get at things.

Hope anyone can pass on their advice.
Mike

Mike,

 

I have 2 ramps (gradients), one at ~1in40 and the other at ~1in48. These go around the room between the Upper Level (to be scenic) and the Lower Level (storage sidings) and the curves are ~650mm radius. All my locos are diesel but no PowerBase is fitted (didn't like the idea). With 7 or 8 coaches both ramps work just fine, but I can tell that the slight increase to ~1in40 does make a difference. If you can, try to limit to ~1in45.

 

Ian

 

[The Johnster]

This is one of those questions where the answer it 'it depends'.  It depends on how steep the gradient is (der, no sh*t, Sherlock), how powerful your locos are/how heavy or draggy are the trains they pull, and how tight any curves on the gradient are.  The steepness, as has been pointed out, needs to be measured at the steepest part of the gradient, and keeping to it requires a deal of precision in both making the trackbase of the gradient and in laying the track.  Turnouts need to kept away from the vertical transition curves at the top and bottom and any changes in steepness on the gradient itself.

 

Locos will perform better other things being equal if the power is transmitted to the railhead with a short wheelbase bogie, so steam outline, with it's longer rigid wheelbases, is at a disadvantage, and the Bullied/Raworth bogies on Class 40 and 44/5/6 are not ideally suited.  The problem can be minimised with larger vertical transition curves, but of course this will further eat into your available space.  Loads need to be lightened, but this is a double edged sword as they will be prone to derailment if they are made too light, a funtion of bouncing around at speed and the centripetal force of being pulled inward towards the centre point of the radius of curves.  Anything that drags, even very slightly, will affect the load that can be managed as well, and it is best to ensure that all wheelsets run as freely as possible and that the tyre surfaces are clean; I highly recommend binning any plastic wheels and replacing them with metal types.  Particularly suspect here are trailing wheels on steam locos (bogies and trailing pivoted or radial trucks) and long rigid wheelbase vehicles such as LNER CCTs, which will drag at the flanges on tighter curves.

 

Which segues nicely into the subject of curvature on gradients.  On a gradient, a curve is very difficult to lay accurately, as the inside rail will rise at a steeper gradient than the outside rail, forming a sort of corkscrew.  The best you can do is to ensure that the track is level across the gauge, which needs to be checked with a spirit level at each sleeper if you are doing it properly.  Failure to do this will compromise performance as not all the powered wheels will neccessarily be in full and proper contact with the railhead at all times, which will impair pickup and tractive effort.  Again, the longer the fixed wheelbase and the sharper the curved  the more prone to this the loco will be, and if you are using setrack curves it is worse of course.  For this reason I recommend commercially build spirals if you are going to use one, unless you are very confident of your carpentry and track laying skills.

 

If your plan is predicated on saving space by using gradients it is likely that you are already pushing the envelope and the problems I have outlined need to be fully considered before committing to that plan.  Personally, I would prefer the fiddle yard to be above rather than below the scenic part of the layout, as unobstructed overhead access to this is important.  Many of the Cyril Freezer plans using gradients look very difficult to build accurately and successfully within the space he claims, and while they are theoretically possible I doubt that many of them have ever been successfullly built and operated; you do not see them at shows or featured in magazine articles. 

 

Sorry if this sounds a bit discouraging, but it is better that you are appraised of likely issues before you begin the construction.

[Bittern]

On 20/06/2021 at 23:10, The Johnster said:

Many of the Cyril Freezer plans using gradients look very difficult to build accurately and successfully within the space he claims, and while they are theoretically possible I doubt that many of them have ever been successfullly built and operated; you do not see them at shows or featured in magazine articles. 

I suspect they worked better with the relatively coarse wheel  standards, more flexible chassis, and so on commonly used  when he drew most of those plans. 

[GWR-fan]

What has not been mentioned is the coefficient of friction of the different materials.  Steel wheels on steel rails is apparently adequate but when the tractive wheel or rail material is varied then the performance of a loco will change on a gradient.    Refer following link on coefficient of friction of various materials.

 

https://www.emachineshop.com/coefficient-of-friction/

 

[Il Grifone]

7 hours ago, Bittern said:

I suspect they worked better with the relatively coarse wheel  standards, more flexible chassis, and so on commonly used  when he drew most of those plans. 

 

We didn't have so much stock back then either!

 

I would (like the prototype) try to avoid anything steeper than 1 in 40 (2.5% if my calculations are correct - I still can't  get my head around percentage gradients!). My US steam locomotives can manage around ten freight cars on these without slipping (helped by traction tyres). As previously stated, the diesels have no problems (there's plenty of room in an F7A for weight!).

 

[Crewlisle]

With reference to the track plan of my 00 gauge layout Crewlisle below, the gradients are as follows:

 

Terminus up/down to mainline.  1:38.  Most larger locos can stop & start 6 coach expresses on their way up to the terminus.

 

Mainline down to reversing loop/cartridge exchange system (my fiddle yard) in operating well.  1.28  No problem as most traffic goes down but with the occasional 'up' it requires a gentle 'big hand from the sky' banker.

 

Reversing loop up to up-mainline from under right hand baseboard.  1:33  Joins the up mainline under the coaling stage.  All trains have no problem going up as I have removed most of the weights from the coaches.  My trains are usually 6 coach expresses, APT or Blue Pullman or about 1400mm long freight trains (the length of my cartridges in the operating well}.

 

Many of the locos have added lead weight to improve traction.  I tried DCC Concepts 'Power Base' but when the magnets were added under the loco (no lead weights!) I found trouble when trying to test the locos on their rolling road.  The magnets kept pulling the rollers off the track! 

 

Track radius does not seem to be a problem.  My track radius varies from 450mm to 800mm.

 

May I suggest you forget about a fiddle yard, use the cassette system like mine.  You can fit it If you have an operating well or edge of your baseboard & dispense with any gradients.  If you want a copy of the construction of my cassettes, let me know.

 

Peter

 

[DCB]

The devil is in the detail.  Crewlisle admits he has taken weights out of coaches and added them to locos and his layout certainly works and works well.  He is also an excellent craftsman whose 1 in 28 grade is a genuine 1 in 28 from horizontal. Many of us can't get less than a  1 in 100  grade when we are laying level track.

For a new comer using brand new  DCC steam outline locos I would avoid using any gradients at all.   I have a grade somewhere around 1 in 33 or 1 in 36 and most DCC ready steamers struggle with 4 coaches. Luckily my bankers will push 7 coaches up the grade but the line was built for Hornby Dublo and Wrenn locos which could manage 7 coaches or 18 wagons unassisted.   On full size railways Castles hauled 10 coaches over 1 in 38 grades.

With Traction tyres fitted my lima class 37s pull 6 coach trains up 1 in 14 grades in the garden.   You can use 1 in 30 grades but it's a lot of work to modify steam locos to achieve it.  Those grades allow  fully scenic layouts with hidden fiddle or cassette yards,  For unmodified RTR DCC Steam you really need partly scenic layouts with visible storage or fiddle yards, unless you don't mind 3 coach express trains in which case 1 in 30 may be do able.

I have a video on You Tube of an early 1960s  Triang Britannia on 13 bogies climbing the 1 in 33 ish overtaking a Bachmann "Tornado"  which had slipped to a stand pulling 5  

[RobinofLoxley]

Im planning for between 1 in 40 and 1 in 50 for my layout rebuild. How do folks manage the transition from flat to gradient - the rail will curve naturally to that degree but its the support. I am using 2mm compressible foam and was just planning to build that up where required in layers.

[DCB]

I used sundela board strips  sanded to shape, for the first foot or so until there is depth enough for full depth sundela. it's messy and fiddly but its a solid base for the track.  For the thin edge of the wedge  ramp where I can't sand the sundela thin enough I use thin wood, 1mm?  2mm maybe, mine was venetian blind slats again sanded and filed to profile.   You need to face the reality that some unmodified 2000 on made Steam RTR needs a heck of a long transition, whereas 1960s stuff will not notice if its just an angle.  I had to do a huge amount of work on our Hornby T9 to cure it from slipping to a stand with weight on bogie and trailing drivers lifting the traction tyred leading drivers off the track in th slightest dip.   We used to buy crude reliable strong lusty locos and add detail, now we buy feeble highly detailed ones and struggle to add reliability and power.   Funny old thing progress.

Edited July 9, 2021 by DavidCBroad

[RobinofLoxley]

My stock is a mixture but its all steam hauled, at least up the gradients it would be. I have some modern and some tender drive older stuff that may or may not be convertible to DCC. I have planned to do a test section before I am fully committed. All my gradient sections will have a straight run to them on the 'uphill' side.

[ITG]

I used the Woodland Scenics inclines for the main climbs, and although the bottom section is as thin as it could be, you could see the change from flat to sloping rail quite easily. I used thin card, in varying numbers of layers to graduate the transition, but only over maybe 4” or so. I’m sure a lot depends on what the main incline is, mine is 2%. All (last 20 years) steam and diesel locos handle 6 coaches but as platforms and fiddle yard roads are limited to 4 (plus longest loco), the problem of not coping doesn’t arise.

[ISW]

On 09/07/2021 at 10:08, RobinofLoxley said:

How do folks manage the transition from flat to gradient - the rail will curve naturally to that degree but its the support.

I cut the baseboard, and 'shim' one end of the cut thus allowing the baseboard to 'bend' to a suitable radius. I then 'shim' as required.

It's easier to explain in a couple of photos:

 

This photo shows the adjoining 'ramp' track:

 

I hope this explains sufficiently.

 

Ian

[RobinofLoxley]

58 minutes ago, ISW said:

I cut the baseboard, and 'shim' one end of the cut thus allowing the baseboard to 'bend' to a suitable radius. I then 'shim' as required.

It's easier to explain in a couple of photos:

 

This photo shows the adjoining 'ramp' track:

 

I hope this explains sufficiently.

 

Ian

Wouldn't be possible for me to do that but I appreciate the tip. I have plenty of 3mm ply and as my underlay is 2mm I imagine I can sand 1mm off or bridge with a second underlay.