Minimum radius and steepest elevation in N?

[Reptilian Feline]

I did some checking on minimum radius and steepest elevation in Z scale when I though that was what I was going to model. Now that I'm back to N, I know I can get some experience input, and not just crunch some numbers.

 

I think that I read that elevation shouldn't be steeper than 4%. I assume that it doesn't matter what scale that is. However, I also need to know the clearance of engines and coaches and wagons, so that I can calculate the elevation. For steam LNER, what would be the best number to go by?

 

Also, the radius. With proper banking, and short engines and wagons, the radius can be pretty small, but how small?

 

Setting up XtrCad for the track laying isn't that hard when you have the numbers. BTW what is the space between parallell tracks? I'm thinking that the double crossover switch could work as a template for that, but the software refuses to the list the space between the tracks.

[ikcdab]

The steepest gradient is a function on the power of your locomotives and the weight of the rolling stock it has to pull. 25% may well work for some combinations but not others. Just go for the easiest you can 

A MK1 coach is 13ft (approx) high. You need to allow clearance for bridge girders and the depth of the track.

Curves...a dock layout can have very tight curves. Again, it depends on the stock you wish to use.

[Kris]

Minimum radius for short engines would normally be Peco 1st radius (228mm) however for larger locos you will normally see the minimum radius quoted as 2nd radius (263.5mm). Some newer coaches are also quoted as needing 2nd radius. Peco set track points are 1st radius. 

[jpendle]

15 hours ago, ikcdab said:

The steepest gradient is a function on the power of your locomotives and the weight of the rolling stock it has to pull. 25% may well work for some combinations but not others. Just go for the easiest you can 

A MK1 coach is 13ft (approx) high. You need to allow clearance for bridge girders and the depth of the track.

Curves...a dock layout can have very tight curves. Again, it depends on the stock you wish to use.

 I think you mean 1 in 25 which is 4%. 

 

Anyhow, in my experience running long diesel hauled trains in N then 2%, on a straight run, is the max gradient that I can use. On a curve the gradients would have to be less steep.

 

For track spacing, in Scarm, I just use a couple of Peco Code 55 points forming a crossover to get the spacing right, and then delete them after the fact.

 

Regards,

 

John P

 

 

[Dungrange]

I've no practical experience with N gauge, but I'd say that 4% (1:25) seems a bit on the steep side.  My first layout, built in 00, had a gradient that I think may have been as steep as 1:22 or around 4.5% but didn't last long, as a two coach train struggled up the gradient and didn't look at all realistic as there was a lot of wheel slip.  I can't say I've seen anyone recommend a 4% grade and I think I'd probably try for something closer to 2.5% (1:40) as a maximum permitted grade if I was planning a layout with gradients. If you go for anything steeper, then I'd recommend doing some tests with the stock that you intend to use before committing to a plan.  Remember also to allow for a transition from level at the top and bottom of the maximum grade.  It doesn't have to be a long transition, but possibly a coach length, so say 100 mm top and bottom.

 

http://www.elginmodelrailwayclub.co.uk/2010/articles/advice/standard-railway-modelling-dimmensions.html may help with some planning dimensions.  This indicates that you want a minimum of 31 mm from top of rail to underside of an over-bridge.  To that you need to add the thickness of your baseboard, which might be 6 mm ply, and the height of your underlay (if used) and track which means that you probably need a minimum distance between top of rail and top of rail of at least 40 mm, but unless both your lower and upper tracks are flat either side of the crossing point, you should probably add a couple of extra millimetres to cope with the extra height clearance required at the transition from flat to slope, so as a design parameter, it might be better to use 45 mm. 

 

As for the distance between parallel tracks, the scale distance between track centres would be about 23 mm.  However, that's only really appropriate where you plan to use scale radius curves (ie curves of about 2 m or more in N gauge).  Given the desire to have tighter curves, the space between the tracks has to increase.  You haven't said what track system you plan to use, but Peco sell a track spacer - see https://www.trainshop.co.uk/peco-track-n/1691-6-way-gauge-5050881009307.html?gclid=Cj0KCQjw38-DBhDpARIsADJ3kjla1uRgY758CCNlaREa1FeVWZ8DKoTdmjq35MMy5s9wlw6JK2jO9tsaAtOHEALw_wcB

 

This shows the minimum spacing increased to 27 mm for the streamline range and to 35 mm for the set-track range (although if @Kris's figures are correct, the set-track spacing should be 35.5 mm).  If you're looking at radii less than 300 mm, then work with the set-track figure.  If you have space for radii greater than 500 mm, then you can probably go with the streamline spacing, but it will very much depend on the stock that you plan to use.  Since you are looking at the 1940s era, stock wasn't as long as more modern coaches, so you may get away with the narrower spacing at slightly tighter radii, but that would be by experimentation as it's dependent on the end throw of a locomotive on the inner track and the centre overhang of a bogie vehicle on the outer track.

 

Hopefully that helps.

Edited April 13, 2021 by Dungrange
spelling

[zarniwhoop]

If you want steep gradients, you need narrow gauge and short trains! The comments above about gradients and radii seem sound, except I didn't see anyone mention that a sharp curve magnifies the apparent steepness - probably the drag from flanges.

 

Conversely, on my first layout when I came back I used a 4'x2' board for HOe, approximately an oval, with station and passing loop at one end (so the inner loop is tight) exiting onto a 3% (approx) gradient at the back. The left end is built up with expanded polystyrene and at the front the slope is about 10%.

That worked for two or three 4-axle (bogie) coach trains, although some of the longer Bemo german coaches had a tendency to uncouple on the run into the 3%.

 

But the locos (even the Liliput U2) could run much longer trains on a flat layout and were comparatively heavy (many older N locos are comparatively light, and adding weight has been reported to wear some of them out).

 

I also tried running some 009 stock (small 4-wheel diesel on an N chassis, short trains of 4-wheel wagons) - the locos were not powerful enough for substantial trains.

[njee20]

10 hours ago, jpendle said:

 I think you mean 1 in 25 which is 4%. 

 

Anyhow, in my experience running long diesel hauled trains in N then 2%, on a straight run, is the max gradient that I can use. On a curve the gradients would have to be less steep.

 

For track spacing, in Scarm, I just use a couple of Peco Code 55 points forming a crossover to get the spacing right, and then delete them after the fact.

 

Regards,

 

John P

 

 

I think it’s an exaggeration to prove the point. If his stock gets up a 25% climb then that’d be the maximum. No point saying to keep below 1% if all the OP wants to run is a railcar representing a rack railway. Ditto curve radii - if stuff gets around a 150mm curve then that’s the answer.
 

I’d agree at 2% being a sensible target, but actually unless you’ve got a big layout that’s hard to stick to, needing a run of 4m to get up to 40mm and down again, assuming nothing flat at the top. I’d urge the OP to test it first - just prop up a plank with some track and see. N gauge stock is not known for its haulage capabilities. 

 

Curves you just want as gentle as possible. If you can stay above 10” you’ll be rewarded with better running. Most items of stock will negotiate 9” curves, but they’ll look silly doing it, and/or won’t like it!

[NIK]

Hi,

 

Sometimes a train may make it up a gradient but at a reduced speed so the max gradient may depend on whether it is part of a scenic section of the layout or a hidden section.

 

Also would the slowdown due to the gradient be acceptable in terms of layout operation.

As has been said using a plank of wood to do experiments is useful especially in N as you can get a reasonable length of track on a plank and get a stopwatch out to time the train if needs be.

 

I don't know whether DCC Concepts Powerbase or a DIY equivalent can be used in N but in OO I found it reduced wheel slip noticeably.

 

Steam outline model locos especially higher speed passenger locos can suffer from lack of grip and if a gradient on a layout is too steep there is little that can be done afterwards to improve things.

 

Regards

 

Nick

[Kris]

1 hour ago, NIK said:

I don't know whether DCC Concepts Powerbase or a DIY equivalent can be used in N but in OO I found it reduced wheel slip noticeably.

 

They do a specific n gauge version. 

[Reptilian Feline]

Lots of interesting replies and points.

 

So, first, I'm planning the layout in XTrackCad and the Peco libraries. My plan is to use the Peco points with Peco flextrack. It will be a DC setup, no DCC, mostly because of the cost.

 

Xtrackcad is a bit fiddly when it comes to nice changes for sidings and so on. I want to set it up with a realistic number for the tightest radius, because this is also what it uses when connecting tracks to points.

The software has a parallell track button. Very useful when making up stations, and it was set at 50 mm spacing. I tried to match the very impressive crossover from Peco, but wasn't sure I got it right.

 

The software also has a feature so I can check gradients, but I need to know the spacing between levels to set it up properly. 

 

I have a general area for where I can put the layout, but the size is somewhat flexible, but on the smaller side, and I'm trying to figure out the smallest size I need for the station and its sidings, where it will still be useful.

 

The layout will probably be O shaped, so I might not need the tightest radii for the main curves. It will be single track in and out of the station, but hopefully with a way to chose between two routs once the train leaves the station. I don't want the layout to be too flat, so some elevation and hopefully a viaduct will be part of the layout as well.

 

I probably won't have the luxury of testing gradients before hand, so I'd rather play it safe.

[Dungrange]

7 minutes ago, Reptilian Feline said:

I don't want the layout to be too flat, so some elevation and hopefully a viaduct will be part of the layout as well.

 

I probably won't have the luxury of testing gradients before hand, so I'd rather play it safe.

 

You don't actually need to have gradients to avoid the layout appearing flat if you were to use an open frame construction.  There is no reason why you couldn't have the track bed perfectly level, but have the scenery both above and below track level.  That should look more realistic than trying to incorporate gradients onto a flat board just to accommodate a viaduct.  For example, the steepest gradient on the Settle and Carlisle railway is 1:100 (ie 1.0%), but much of the route is flatter than that.

 

If you need to incorporate gradients because you want to have one line crossing over another, then try to design the plan so that one track drops down (20 - 25 mm) and the other track climbs (20 - 25 mm), so that neither track is overly steep.

[njee20]

Totally agree with the above. Adding gradients for some visual interest on a flat board will look contrived and unrealistic, because it is. Instead of considering the track level datum as the baseboard surface think about raising everything up, either by putting the track bed on risers above the board, or by building sufficient depth in the frames that you can have the land falling away below the track. It’ll look far more realistic, and not bring any of the headaches of incorporating gradients. Check out the open frame baseboard concept. 
 

50mm is the Peco set track separation, designed to be far enough apart that stock doesn’t clash on tight curves. For streamline it’s about 27mm, but you may need to widen this slightly on curves to avoid items colliding. 

I’d  recommend using code 55 track as well, it looks more realistic, it’s stronger and there’s a greater range of turnouts and crossings. 

[Chris M]

I agree with pretty much everything that has been said above. I did a "haulage test" video a while back which shows how different locos are. 

 

 

 

I would say Peco R1 or tighter are best avoided. Peco R2 is ok for most things but there are exceptions. The Dapol class 50 has a nice close coupling  but the coupler is body rather than bogie mounted. It is fine with bogie stock but will throw 4 wheel wagons and milk tanks off the track on anything less than R3.

 

I have built three N gauge layouts in recent years. Suffice to say that the latest one has no gradients and nothing tighter than R3 curves. 

 

Open baseboards are by far the best. Plan what the scenery will do when planning the track diagram. Build the boards so that your track appears to have been built through the scenery rather than the scenery built around the track. Land is almost never flat. A layout where someone starts with a full flat baseboard, lays track and then builds some scenery up from that baseboard always looks wrong (to me). 

 

 

[Chris M]

I added lead absolutely everywhere I could on that Castle and it would just about manage 7 coaches on my inclines. Strange thing is, this loco seems to pull reasonably well on the flat without any added weight. 

 

Here is my layout under construction showing the "open baseboards"

 

Here is my 9F showing that it is a competent loco on level track. I'm glad to say that she is no longer a shelf queen. You can also see a bit of the open baseboard in the background, and proof that I am not a carpenter.

 

And finally, what open baseboards and level track look like when completed.

 

 

Edited April 14, 2021 by Chris M

[Reptilian Feline]

Thanks for the wonderful videos.

 

• So... try to avoid gradients... but if need be, then let one track half down, the other half up.
• Use Peco 55 and R3 curves if possible.
• Do open baseboard for better realism.

I set up the parallell track in the software using the Peco scissor crossover as a template. It helps me when connecting points and sidings in the software. Wider gap in curves is a given, even when banking.

 

I have to set up engines, carriages and wagons to see how long my sidings need to be. I just hope that the ones I want to use have their measurements posted somewhere.

 

I have plenty of square tubing in aluminium and corner joints to make the "table"-legs, so I don't think that should be much of a problem with making the open baseboard. It should still be pretty stable. I'm used to working in papier maché, so the landscaping shouldn't be much of a problem once I get started.

 

BTW... I didn't know you put points on a gradient.