Starting Gradients

2384 Views 17 Replies 12 Participants Last post by Fireline, Jul 28, 2008

Fireline

Discussion Starter · Jul 20, 2008

I am deep in the building of my layout, and I have suddenly realised that there is no limit on my lack of knowledge! I am building gradients, but I don't know how to START them off from the level. I don't want to bend the rail, so will the rail simply lean slightly, or is there a better way of packing it out? I am looking at going for 1 in 40+, if that helps.... Any tips GREATLY appreciated.

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TonyDaly

· #2 · Jul 20, 2008

QUOTE (Fireline @ 20 Jul 2008, 19:51) <{POST_SNAPBACK}>I am deep in the building of my layout, and I have suddenly realised that there is no limit on my lack of knowledge! I am building gradients, but I don't know how to START them off from the level. I don't want to bend the rail, so will the rail simply lean slightly, or is there a better way of packing it out? I am looking at going for 1 in 40+, if that helps.... Any tips GREATLY appreciated.

Hello.
1 in 40 is pretty steep. The most I would try is 1 in 50 and then only on the straight.

alastairq

· #3 · Jul 20, 2008

favorite is to gradually raise the roadbed in a vertical curve, from the flat, to the desired gradient.

In much the same way as transition curves lead from the straight to the required radius.

You don't mention what type of roadbed you are using?

Easiest to get a smooth vertical transition is a plywood roadbed........by cutting out the intended trackbed using a jigsaw, and gradually introducing wood wedges underneath, the ply adopts a natural transition. The trackage will find it easy to follow the gradual increase in gradient of the roadbed.

what needs to be avoided are abrupt changes of gradient........for longer wheelbase stock this can be a reliability nightmare.

This is one reason why the addition of different levels requires far more space than folk imagine.

Brian Considine

· #4 · Jul 20, 2008 (Edited by Moderator)

As Tony says 1 :40 is pretty steep - it really depends on what locomotives you are using & train length/friction/weight - many modern locomotives have immense haulage capacity, so your gradients may be limited to what "looks right".

Try to get as smooth a transition from level to gradient as possible - Alistair's method is probably the best to achieve this & the way I would do it also. What you really need to avoid is an angle in the rail - don't forget to apply the same principle when you go back to the level at the top !

Whatever you do try & avoid curves on steep gradients, they can cause a lot of friction.

TonyDaly

· #5 · Jul 20, 2008

QUOTE (Fireline @ 20 Jul 2008, 19:51) <{POST_SNAPBACK}>I am deep in the building of my layout, and I have suddenly realised that there is no limit on my lack of knowledge! I am building gradients, but I don't know how to START them off from the level. I don't want to bend the rail, so will the rail simply lean slightly, or is there a better way of packing it out? I am looking at going for 1 in 40+, if that helps.... Any tips GREATLY appreciated.

Hello.
If you give us some idea of what you are building I am sure you will receive all the help you could ever want on this forum. A track plan would be a good start. It doesn't have to be a draftsman plan or anything special. Just to give us some idea of whats involved. The people on this forum are extremely helpful.

Fireline

Discussion Starter · #6 · Jul 20, 2008

Hi. Thanks for the thoughts guys. I am building a railway that runs round my full loft, so it is 20' by 12', and on boards of 2' depth. I can't put a diagram up at present, as I haven't got one! I am building it in conjunction with my dad, and he is the design genius! What I have is 2 outside loop lines, that will raise 2" over 10 feet on one side, and 9" on the other (so 1 in 50 and 1 in 45 nominal). The thing is, under the lifted section will be a tunnel section with storage roads, so that will drop 2" from the same point. The two levels will have a gap between them of 4".

In order to build this, I am using MDF as a base board. The slopes will be on straights, so I shouldn't have too much to worry about. I am only looking at running 4 coach trains, or so, so traction is not a huge issue. I have set a test board up, and checked loads at 1 in 40, and it was ok for me.

Oh, and Brian, all this is happening no more than three miles from you!!!!

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Robert Stokes

· #7 · Jul 20, 2008

A 2" rise in 10ft is actually 1 in 60. however if you have a bit of transistion top and bottom this will end up with the main part being at about 1 in 50 so that should be O.K. The other side 2" in 9ft averages 1 in 54 so again with transistion the main part will be about 1 in 45.

60159

· #8 · Jul 21, 2008

QUOTE (Robert Stokes @ 20 Jul 2008, 22:30) <{POST_SNAPBACK}>A 2" rise in 10ft is actually 1 in 60. however if you have a bit of transistion top and bottom this will end up with the main part being at about 1 in 50 so that should be O.K. The other side 2" in 9ft averages 1 in 54 so again with transistion the main part will be about 1 in 45.

Hi, for the all important transition between flat and incline I used good old polyfilla over stepped layers of cork to form the very gradual transition to the inclined baseboard. I took some time and care to get it looking just right. At the top I left a bit of the inclined baseboard unsupported and the natural bend of the board from the top of the supported gradient to the flat worked beautifully - probably luck!

It's worth noting that I've found there is great inconsistency between RTR locos on their ability to cope with a challenging incline - my poorest performer in this respect is the Bachmann standard class 4 tank. (Let me know if you want a rundown of how my 20-odd locos perform!)

Cheers Mike

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Chinahand

· #9 · Jul 21, 2008

Hi Fireline and welcome to the MRF.

As Alastair says, plywood is probably the best material for constructing gradients, particularly transitions as it adopts a smooth transition line almost by itself. For the transition I work on a rough 'rule of thumb' and actually do a double transition by rising half the mean gradient over the first 300mm and then going to the full gradient over the next 300mm. This spacing is set by my open grid baseboard system.

So if your mean gradient is say 1 in 50, rise by 3mm over the first 300mm and then by 6mm over the next 300mm. Maintain the 6mm per 300mm until you are 600mm from the summit and then reverse the process by rising only 3 mm over the next 300mm. This does mean that the length of your gradient is actually 600mm more than if you drew a straight line between the two points, hence Alastair's comment about gradients taking more space than you may, at first, realise.

Hope this helps,

Expat.

john woodall

· #10 · Jul 21, 2008

A reasonably quick way to get gradients is to use the woodland scenics polystyrene.

These are preformed so really useful.

As a general rule of thumb I have maximum 4% grades on straight track and 2% on curves. If I had more space the layout would have been dead flat, but . . . . . . . . .

John

Richard Johnson

· #11 · Jul 21, 2008

QUOTE (john woodall @ 21 Jul 2008, 14:21) <{POST_SNAPBACK}>A reasonably quick way to get gradients is to use the woodland scenics polystyrene.

These are preformed so really useful.

As a general rule of thumb I have maximum 4% grades on straight track and 2% on curves. If I had more space the layout would have been dead flat, but . . . . . . . . .

John

***John....4% - 1 in 25!! Bloomin heck, a mini funicular indeed - Then again Marklin puling power is legendary, and marklin track is steel or s/steel so not slippery like nickel silver, so you will get away with things Brit modellers cannot. Still, it really steep aint it!

***Fireline????
You have some really good advice already. Best running, best reliability and best "look" on a layout means nothing extreme or sudden. avoiding abrupt changes makes models both look and run better with no exceptions!!

no sudden changes from flat to gradient - always have a transition
no sudden changes from curved to straight - always have a transition
resist cramming track and use largest possible radii curves - always have a transition
use largest possible radii pointwork
no right angle corners in backscenes
no abrupt edges where backscene meets baseboard

BTW, customwood bends as well as ply, so the material is not an issue there.

regards

Richard
DCCconcepts

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hairyhandedfool

· #12 · Jul 21, 2008

2

I have two gradients which some may consider steep. both are rising 4 1/4 inches over about 10ft. the one pictured below also includes a curve. but as I only run DMUs and small freight over this one it is not so much of an issue. Trains over 7 coaches can struggle though.

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Chinahand

· #13 · Jul 21, 2008 (Edited by Moderator)

Yep. 1 in 28.2 is steep but, as you say, you can get away with it for short trains.

That's a pretty busy looking layout by the way.

I have developed an Excel spreadsheet to calculate the height of my risers at any given point based on the overall distance, a starting (datum) level and and a finishing level. All I have to do is input the distance from the start point and out pops a riser height. It also takes account of transition curves at both ends.

Cheers,

Expat.

Lancashire Fusilier

· #14 · Jul 22, 2008

See there's that scary photo again of unsupported track with a loco going over it. Freaks me out every time I see that one

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hairyhandedfool

· #15 · Jul 22, 2008

2

QUOTE (Expat @ 21 Jul 2008, 16:03) <{POST_SNAPBACK}>That's a pretty busy looking layout by the way.

yeah, I had a spell of just buying trains, which I am mostly past thankfully, but I needed space to run them or what was the point!

QUOTE (Lancashire Fusilier @ 22 Jul 2008, 03:36) <{POST_SNAPBACK}>See there's that scary photo again of unsupported track with a loco going over it. Freaks me out every time I see that one

Its following you around!!!

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SRman

· #16 · Jul 22, 2008

IIRC Melbourne's suburban trains have to cope with gradients as steep as 1 in 27. They are electric multiple units but it still shows there is a prototype for everything.

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Fireline

Discussion Starter · #17 · Jul 26, 2008

Hi. I still don't have the plan, I'm afraid. But I have realised that I do have a number of pictures of what I am doing, but I'd forgotten all about them!

They can be found at:

http://modelrailway.fotopic.net/

I will try and put some more explanation on the pics when I can.

Fireline

Discussion Starter · #18 · Jul 28, 2008

Right. Thanks for all the tips guys. I have laid a test slope in plywood, and it has come out to ABOUT 1 in 45. Certain engines aren't really that keen, particularly the Bachmann 4mt's and the Hornby Prairies. Strangely, the least upset engine was an old Mainline 43xx, with suspect traction tyres, that hauled 8 old and heavy coaches up without a single slip!!!! 80 odd engines to test, then....

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