Gradients.... how much is too much?

[Zerogee]

I'm at last in the position to start some serious layout planning, so need to start thinking about gradients and suchlike..... I know that the golden rule with gradients is to minimise them wherever possible, of course, but if you have to have them then what is the maximum that typical LGB locos will handle with reasonable train lengths - preferably without double-heading, adding extra weights or other fiddling about. I've read all the stuff in the books about keeping to about 3% maximum, but I'm interested in actual experiences from all the layout builders here - have you ever put in a gradient that was simply too steep and had to rip it out again, or have you been surprised when your locos happily stormed up something that you had though was way too much for them?

Thanks in advance for any advice!

Jon.

 

[bobg]

The story of gradients is not simple. It's more a case of what you can get away with and where. Bearing in mind what you said about minimising, the shorter it is the steeper it could be, is one way to look at it. Also, can you get a clean run at it? Is it on a bend? How big a train do you want to pull? I have a 15m 1:40 with a double curve in the middle, which is about as much as my loco will manage with a decent size train, and without slipping.

 

[korm kormsen]

i built two straight gradients of 6% (one in 17) eleven meters long (35foot).
a single Stainz with about one pound of additional weight draws either five LGB or playmo fourwheelers or four eightwheelers up these gradients.

the problem lies in curves!
leading to these gradients i built graded curves. - and rebuilt them - and rebuilt them - and...
the above mentioned cars drawn by a Stainz plus motorized tender will stall on a R1 curved grade of only 3%!
at the moment i am trying to keep the sharp curves under 1.5%.

 

[Zerogee]

As the (very rough) planning stands at present, I'm not looking at any curved gradients - just a single straight run that needs to climb about 250mm over a roughly 6 metre length, which works out at just over 4% I think. Should this be do-able? The rest of the track will be ground level and gradient-free.

Jon.

 

[korm kormsen]

with trains of not more than 2meter total length it should be doable.

 

[gregh]

If you really want to do some planning (not guessing) about gradients, here?s a ROUGH calculation method. It will generally underestimate the load you can pull.

You?ll need some kitchen scales to measure the mass of your locos and wagons.
Then???
[OL][*] measure your loco weight (that?s the weight on the drivers only if possible) Call it Mdrivers (grams)

[*] measure the total weight of your loco plus tender (if applicable) Mloco in grams

[*] get your curve radius in metres. I assume that a curve of radius R metres is equivalent to a grade of 1/R %. (note that Korm states that a R1 curve (0.6m rad) is equivalent to 3% grade, which is about twice as bad as what I assume. So you might like to use 2/R% instead.)

[*] get your gradient in % (If you use 1:X system, just divide 100 by X to get %)

[*] From tests, I assume that the drag of wagon wheels/bearings is equivalent to a 0.5% grade for plastic wheels and bearings; 0.2% for steel wheels.

[/OL] Now get the total drag of the train as an equivalent gradient percentage = radius% + grade% + wagondrag%.
You might have values around 2-5%

Now here?s the equation you use:

Mass of wagons you can haul = 20* Mdrivers / total drag % - Mloco


(The 20 comes from my assumption that the loco adhesion is around 20%.)

Seems complicated , but simple after the first time you do it. Here?s an example:

Say the loco has 1000g on drivers and a total weight of 1500g. You have a 4% grade, with a 2m radius curve and have steel wheels.
Train drag = 4% (grade) + 0.5% (curve) + 0.2% (bearings) = 4.7%

Wagon mass you can haul = 20 *1000/4.7 ? 1500 = 2700 grams.
Now you just need to measure your wagons? mass.

For a level track, and R1 curves, the same loco should haul 20x1000 / (.2 + 1/.6) ? 1500 = 9000g !

 

[bobg]

There is an even simpler method, to gregh's. Find yourself a long scaffold board and lay some track on it, then pack one end up a bit at a time till you achieve your traction limit, or the grade you propose. Simples.

Edit : - I could add to that, that if you can manage the grade from a standing start, it will it fly with a rolling one.

 

[stockers]

Try this thread

http://www.gscalecentral.net/tm?m=46870&high=gradients

 

[korm kormsen]

gregh,
i tend to advocate bobg's method.

for two reasons:
1) its more fun to build up and tear down test tracks, than to do mathematics i don't understand.
2) there are some additional factors to recon with. as:
a LGB postvan with metalwheels (and powerpickup) drags more than a normal freightcar with plasticwheels.
in curves a Bachmann fourwheeler with its rigid aixles is dragging for three and so on...

 

[Neil Robinson]

I fully endorse Korm's previous post and would like to add a couple more factors.
The drag of LGB twin axle stock varies a lot depending on how well or badly the axles align and realign to the track whenever the curvature varies. This means two similar trains may have a very different load on the loco.
As with the prototype poor rail conditions such as dampness, tree sap or grease can make a big difference. A train may have no problem one day but the same train may slip to a stand on another day.
Regarding slipping I don't mind it as I would rather a loco slip than stall. IMHO if a loco stalls then it overloads the motor and maybe it has too much ballast weight. I'm also cautious regarding traction tyres for the same reason.

Nigel, I'm not that familiar with current F.R./WHR tactics, but that was usually the case. Additionally as it is a relatively short line run by people with good operating knowledge day to day changing of loadings can be made dependent on conditions.
For example I once fired Linda when she hauled 12 bogies unassisted over one section of the F.R. under good conditions, yet the recent weather saw a WHR Garratt double headed with their Funkey diesel with only 7 coaches.

Edit, extra comment in reply to Nigel.

 

[bobg]

As with the prototype poor rail conditions such as dampness, tree sap or grease can make a big difference. A train may have no problem one day but the same train may slip to a stand on another day.
Regarding slipping I don't mind it as I would rather a loco slip than stall. IMHO if a loco stalls then it overloads the motor and maybe it has too much ballast weight. I'm also cautious regarding traction tyres for the same reason.

Slipping rather than stalling is a deffo with electric power. With steam it doesn't matter. An additional factor is what oil, or how well lubrcated your stock is. I ran some simple experiments last summer mainly to amuse/interest "small personage". We placed an old L.G.B. wagon (plastic wheels) at the top of the straight section of my grade and from a marked point released it with no push and marked how far it got along the level, repeated two or three times for an average. We then lubed it using clock oil and repeated the tests. As an additional test we then lubed with std engine oil and the result was quite remarkable, the distance increased by several feet. It kept S/P busy for an hour or so anyway. As the old saying goes "what goes up, must come down" so it must apply in the upward direction as well.

 

[whatlep]

Well you could say the steeper, the better. Why? Well, if your small loco can't climb it, you'll have to go out and get a nice, shiny big loco. Longer trains which big loco can't handle? Go for double heading with 2 big, shinies. I mean, who can avoid the logic: you just have to acquire more engines. Gradients - they work for me....

http://www.youtube.com/watch?v=bhJjBDUfl50

 

[Zerogee]

Well you could say the steeper, the better. Why? Well, if your small loco can't climb it, you'll have to go out and get a nice, shiny big loco. Longer trains which big loco can't handle? Go for double heading with 2 big, shinies. I mean, who can avoid the logic: you just have to acquire more engines. Gradients - they work for me....

Having spent the last few years collecting stuff ready for the day when I could start to build a permanent line, I already have FAR more locos that I really ought to have....

That's not to say I have more than I WANT, of course - the principle I work to is: "if some is good, then more is better, and too much is just enough".

Thanks for all the advice so far on the gradient issue!

Jon.

 

[CoggesRailway]

I built my current layout with an eye to reducing gradients to nothing if at all possible. Then after a visit to whatleps I have been thinking how to incorporate a hilly branch - it gave the layout a lot of interest- what would pull what etc, which is what the real railways must have to do to. I have a pair of lgb alco (avatar) either one of which pulls everything i own on my r5 and level layout including the kids playmobil and in a way this is a shame.... I doublehead two of these and it is purely for the look where as whatleps two mallets are required for their job... know what i mean? Maybe I am odd..... I said similar to the wife and she said toy trains aren't actually required at all... tsk.

 

[whatlep]

Maybe I am odd..... I said similar to the wife and she said toy trains aren't actually required at all... tsk.

Nope - you're as normal as the rest of us.

Oh dear....

 

[3Valve]

Too steep??

 

[coyote97]

Too steep?

Depends on:
should be possible with a Locher-Rack.


But what is too steep, really?
The only thing for a MODELLRAILROADER is to say:
It lies in the eye of the beholder!

U can fit a Train with half count of cars acting as locos with rubberrings and the other half to pick up current. That will make it possible to climb ridiculous gradients.....but what for?

Its a Question of likes and dislikes of the builder. I think the facts for going prototypical in some way were discussed often enough.
Therefore, all between 1% and 15% is possible.

Look at our German "Deutsche Bahn": they are building highspeed tracks with 4% gradients. Best rails and most expensive tracking, but nearly impossible to have a freight going along those lines.
All a question of motivation, likes and dislikes.......

Greetings

Frank


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[beavercreek]

When I started to build my layout I put to the back of my mind, the fact that there is a 3 foot rise up to the arbour (Arbour Summit) which has to be climbed by a shortish pretty straight route and then dropped off on the other side with a tortuous curvy route as the track follows the edge of the lawn area.
It was only when everything was ready and I changed from testing locos on their own to actually adding consists that I found out how much of a slope I had!
I now use triple or quadruple heading lash-ups or 'helper' cars which have motors in them (especailly useful with Bachmann Annies which have no real ooomph for my inclines even with extra weight). I also have found that USA Trains deisels have the best record on my layout as they have traction tyres.

I have had to put extra traction wheelsets on my LGB Uintah mallett and the also the Sumpter Valley variety.

Garden showing the incline to 'Arbour Summit'

GPs tackle the gradient

An Accucraft K@& can get up but will only pull 2 or 3 1:20.3 scale cars even though it weighs a ton

Triple or quadruple heading is the only answer for a streamline consist of 6 cars

 

[Richie]

Have some gradients much like Mikes on my Rio Grande line some sections are 1 in 18 , i also run lash ups of 3 to 4 locos much like the full scale rail road . I have now put in a new line which by passes some of my grades to make it easier for my K -27 and 1:20.3 stock as the loco would only pull 4 to 5 wagons up the grade .

Old line climbs up the wall

 

[CoggesRailway]

richie every time i see that bit of track where the gradient diverges i think it's awesome! Hope you have a an open day sometime so I can see it in the flesh...