Gradients

[GWJ]

Hello all

Some help with gradients please.

What is the height of the upper track on bridges from Hornby and other brands ?  And given that height, what is a typical maximum gradient for a loco with 3 or 4 coaches to get up to that level ?

I'm trying to determine what horizontal distance I need to take a loco up from the baseboard level to cross a bridge over a lower track.

Thanks !

GWJ

[96RAF]

I think when I had a multi-level the clearance required was 75mm so I,worked on a track level of 80mm.

You can easily check this with your tallest stock plus a few mm.

 

Gradients (best avoided in popular opinion) should be no more than 2%, so you are looking at 2mm rise in 100mm distance, so 80mm in 4000mm, although depending upon your 'train' and what is pulling it you could increase the slope but keeping in mind any curve effectively also increases a slope.

 

You can cheat the system by having the under track diving half the height and the over track only then rising half the height and this will foreshorten your required distance by half also. I.e. 40mm each way in 2000mm.

[Chrissaf]

I agree with RAFs suggestions. I use the up and under technique myself (one track goes up whilst the other track goes down). This effectively halves the run up distance to achieve the full height. It takes a large layout to get a 4M (12 feet) run up. Believe me, as someone who has gradients, these kind of run up lengths with gradients are definitely needed with modern light weight locos. Do not underestimate how much drag having a gradient and a curve together at the same time adds to the difficulty of a loco dragging up a rake of coaches behind it. Even a short rake of three or four coaches.

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Knowing what I now know, with the experience of my own multilevel layout. If I was building a new layout, I would NOT be designing gradients into it, unless I was building it in a barn sized space.

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If I wanted to build a two level layout for extra interest in a small space again. I would be making the two levels separate from each other, thus each level individually would be flat.

[LCDR]

From bitter experience I would say keep the track as flat and level as possible. And check it with a spirit level too. Unless of course you will only be runnng trains of 2 bogie carriages or 4 trucks avoid any gradient whatsoever.

 

My garden railway does include some shallow gradients and these certainly sort out the good from the bad. Fortunately most O gauge tinplate has considerably more pulling power than modern OO plastic.

[Jimbo1707820979]

Hi GWJ.    I was taken by your inquiry about elevated track. I am only a relative beginner but thought that a line crossing over my outside tracks would add some interest to my smallish layout. I will post a photo separately which may be helpful to you in deciding what to do.  The gradient is fairly severe but small 0-6-0 locos seem to cope with it OK but only hauling a couple of light wagons or short coaches. (My Lion and Kestrel are definitely barred access - a bit like the GWR Kings when they reached the Tamar River !!  )   The radius is somewhere around 3rd. - difficult to say exactly as part of the track is made up of semi-flexible. I would say it has been a bit of a success, the only drawback being slight more diffult to clean the lower tracks.

So I would say don't be put off. Have a go. You can easily change things if it proves a flop. (Like BR ? 😆). The photo will appear on Monday hopefully.

Kind regards

Jimbo

[Jimbo1707820979]

For GWJ. (Others please don't laugh)

Some blurring lower in picture as a result of being a "grab" from video, so moving trains not caught. I guarded against locos falling from the elevated section by using clear celluloid railings. If there's a chance of hitting the deck you can be sure they'll take it .

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[BR63]

I have just built a viaduct with ramps upto and down from it. All Hornby bridges/ piers etc are guaged to suit a 80mm track bed to track bed rise. I too wondered about grades and after a lot of research decided to use 1:40. (i.e. 3.2m length for an 80mm rise). One ramp was straight and the other swan necked.  Both appear to be no problem for my elderly (1978) Britannia and my more recent B17 Class Barnsley each pulling a 7 car rake. I changed the wheels of some older carriages to pinpoint bearings which had a tremendous benefit. Dont forget to allow sufficient clearance over the lower track to allow for bridge construction depth.

[Flashbang]

Hi

For OO the minimum recommended clearance is 60mm. This measurement is taken from the lower levels rail top (not baseboard surface) to the underside of anything above. See OO structure gauge... http://www.brian-lambert.co.uk/Hints%20&%20Tips.html#00

 

For gradients 1 in 30 is the recommended minimum. That's rise 1inch or 1 Cm for 30 inches or 30 Cm of length. Ideally shallower is better i.e. 1 in 50.  Note where a curve is involved in the rise you should then ideally make the rise shallower due to the drag created by pulling carriages or wagons around the curve.

[GWJ]

Morning everyone

Thanks for taking the time to share your knowledge and for the photo, Jimbo - that's something like I had in mind too - to add some dimension and interest.  I'm coming back to all of this after 30 years away - my dad and I built a baseboard and layout and now it's my turn with my son.  I kept all my rolling stock, but not the layout.  What I can't believe is that some of the Hornby kit (e.g. stations, building, signals), haven't changed or updated at all !

Gareth

[Britannia Builder]

I've been building my layout over the past 9 months after 60 years away from the hobby. The gradient in the photo below is 2.4 metres long with two 90 degree 2nd radius bends, rising 80mm to the high-level station on the left, and all my locos will pull 3 carriages or 7 wagons up it without problems. There's a point immediately after the top of the gradient and I had to pack up the last couple of straights at the top of the gradient to avoid an abrupt change in angle at the top, to avoid leading bogies being lifted off and derailing on the point.

 

I certainly think that the gradient and the tunnel add interest to the layout.

 

Regards, John

 

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[samfieldhouse]

I have a fairly extreme gradient on my layout. It rises from flat to the second level which is 8cm above the lower level over the course of a second radius curved half circle. 

The gradient is probably between 1 in 8 and 1 in 10? 

This isn't a 'through line' it simply connects my upper loop and sidings with the three loops on the lower level, so it's mainly lone engines running over it with the odd freight set. 

All my locos handle it well, the smaller ones having the greatest difficulty hauling stock over it. 

However, the visual impact and fun in building it far out way any negatives. 

[Bulver]

Lovely layout, BritBuilder, lots of interest, both scenically, and track-wise, well done

Rod

[RDS]

@Britaniabuilder

Your layout looks really good, thanks for sharing it with us.

[Class 08]

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[Class 08]

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[Class 08]

This is one of my gradients. Seems to work well, but nowhere near finished. 

[DJIW]

Gradiants interest me too. Mainly because I want to recreate a closed line here - so it would need to climb up onto a viaduct, over the river, down onto the flat area then along the river into another closed station, before it turns back towards where it first came, under a tunnel and back into the station with the viaduct. Got a lot of thinking to do, although I know the design in my head!

[Jimbo1707820979]

@ Class 08

Very nicely done. Hope to see more pictures when further work completed.

[Sultan]

I would suggest no steeper than 1:40 and avoid very shrap curves.  Mine a re a minimum of 950mm radius.  You can see some trains on my layout on my Liskwithiel Road FB page at  http://bit.ly/2jsR2wW including Hornby 28xx on a coal train climbing the gradient.

[81F]

 My gradients are generally fairly shallow (about 1:50 except for a branchline which is about 1:30 on a curve. Having a curve on a gradient will make things worse so if you can keep it straight all the better.

 

The gradient was chosen to be the steepest that my bachmann 57XX would pull 4 21T coal wagons and a Toad up. However, my newlt aquired W4 Pecket seems to be able to do a bit more! So it really depends on which locos you have.

 

One tip for getting one rail over another is to dip the line going under as you raise the other. This can shorten gradients by up to half.

 

Hope this helps