Wheelspin/Gradients

parksider · Posted: Mon Nov 10, 2008 4:16 pm

On my being-built HO layout there is a steep grade which I'm stuck with because there isn't enough space to make a longer, easier gradient. A couple of my locos get half-way up with their trains then spin their wheels and can't get any further.

My questions to the more experienced model railwayers are:

1. If I leave things as they are will the problem get better or worse? (I'm wondering if the track - brand-new Peco Streamline 100 - will develop a better-gripping surface with use.)

2. Does adding extra weight to a loco help with traction, or does it just make the job more difficult for the loco because there is more total weight to lift?

3. Will the problem disappear when I switch to DCC? (I'm building the layout and testing sections as I go using an old DC transformer and controller that I've got on hand, but plan to use DCC once the track-laying is complete. One of the locos that spins its wheels is fitted with DCC, but the other is DC.)

4. Are there any options to get around the problem apart from (a) shorter trains or (b) banking locos?

Thanks in advance for any advice.

Parksider

wrongroad · Posted: Mon Nov 10, 2008 4:53 pm

G'day parksider,
I'll try to answer your questions from my own experience.
I have one very steep but short grade and these are my observations.

1. The problem will stay the same. My track has been in place for about ten years now and the same trains slip to a halt at the same place.
For the record I used Peco code 100 flex.
2. Extra weight, in the loco, will help to a certain extent but is not the be all end all of your problem. Too much weight may cause a loco to stall but not slip resulting in the possibility of burning out motors or stripping gears in the worst case.
I believe it is much better to slip to a halt. Others may beg to differ and I'll respect their views on this as should you.
3. Simple answer is no. I ran on dc and switched to DCC seven or eight years ago.......no noticeable difference.
4. You have kind of locked yourself in here by saying you do not want to run short trains or banking engines,
By what you have said, lessening the grade is not an option either. Other than offering a silly solution (helium in your rolling stock) I have nothing to offer you here.
Good luck.
Regards and respect

Enjoy the world we make

Your model rail road is a work of art. Be proud of what you can achieve and strive to be better.

parksider · Posted: Mon Nov 10, 2008 4:59 pm

Thanks for those comments. I'm not against shorter trains or banking engines but just wondered if I'd overlooked some other solution.

Parksider

jd4980 · Posted: Mon Nov 10, 2008 5:01 pm

My 2 cents for what it is worth.

The problem definately won't fix itself neither in time or migrating to DCC.

For the situation in which you find yourself, wheelspin is your friend, as you aren't damaging anything, if loco's were comming to a stand due to the load but maintaining adhesion, isn't good at all and when things like drive shafts especially will break.

See the problem as your friend, not sure on the details of your layout but if banking trains is required, it can be a great first step into some interesting layout operations. I had a section on my layout purposely built steep to require attaching and detaching bankers either front or rear between 2 locations but have since redesigned this area due to another problem that identified itself and would have been encountered if i left it the way it was.

NSWRTM123 · Posted: Mon Nov 10, 2008 5:53 pm

An easier grade does not have to be straight. The Southern Highlands line is a good example. Grades are 1 in 50? at their steepest, and the ruling grade is 1 in 75? Someone correct me if I'm wrong. COuld you post a track plan showing the location of the gradient.

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B 67 · Posted: Mon Nov 10, 2008 6:45 pm

Parksider, perhaps you could tell us what kind of locos you're using. If diesels, are all wheels driven? If you're using the kind of models that have only one bogie powered, then you may be in luck. Fitting a second one can make a big difference.

A friend of mine had problems with Lima locos slipping with a moderately long train on a moderate grade on his layout. He tried using 3 Lima locos and they still struggled a bit with the same train, but it crested the grade. I added a second motor bogie to one of his locos and that single loco could haul the same train with ease.

However, in most other cases, there's probably little you can do to improve traction. Adding more weight is easy enough to try. If it doesn't make a difference, or makes it worse, then just remove it. If the loco has unpowered wheels, there's no point adding extra weight over those wheels.

Perhaps you could also give us an idea how steep your grade is. How many cms does it rise, and over what length of track.

Generally models don't like gradients much steeper than the real thing. Steeper than 1 in 30 is where things start to get limiting. Steeper you go, the shorter the trains will be.

http://www.panoramio.com/photos/original/10772640.jpg
http://www.panoramio.com/photo/10772640
One of my pics showing a 1 in 16 adhesion only grade at Alishan, Taiwan (Shay territory).
This line usually has trains of 4 short carriages per diesel loco. The train in the background is on level track. Wink

B 67

*Most consistantly ignored Railpage Australia™ poster - 1977
*Best username incorporating a B class number between B 66 and B 68.

Gunzel Gallery

supersix · Posted: Mon Nov 10, 2008 8:20 pm

you could add a traction tyre maybe to increse tractive effort

my youtube videos can be found here http://www.youtube.com/profile_videos?user=supersix3801

B 67 · Posted: Mon Nov 10, 2008 8:31 pm

Only if the wheels are designed to take them. Wink

B 67

*Most consistantly ignored Railpage Australia™ poster - 1977
*Best username incorporating a B class number between B 66 and B 68.

Gunzel Gallery

parksider · Posted: Mon Nov 10, 2008 8:51 pm

Thanks B67. I've got an Austrains Y class and an Austrains T class, and both bogies on each appear to be powered.

My track rises about 85 mm in a curved length of about 1400 mm.

The comment about traction tyres sounds interesting, supersix. I'd like to know more about them.

Parksider

B 67 · Posted: Mon Nov 10, 2008 9:02 pm

Many locos used to have (and some still have) rubber tyres fitted to one or more wheels to increase traction. However, the wheels for these were grooved to take them. And the wheel couldn't collect electricity from the track if so fitted. Fitting such to an Austrains loco isn't recommended. To do so, you'd need to modify the wheels, or at least one wheel. A lathe would be needed.

B 67

*Most consistantly ignored Railpage Australia™ poster - 1977
*Best username incorporating a B class number between B 66 and B 68.

Gunzel Gallery

SteamtoStay · Posted: Mon Nov 10, 2008 9:38 pm

alltrainzfan · Posted: Tue Nov 11, 2008 3:57 pm

If you ran DCC, had grades, and had a loco running up a steep grade with a decoder equipped with BackEMF, doesn't that help a little? Confused

Draffa · Posted: Tue Nov 11, 2008 5:05 pm

BEMF would just keep the motor spinning at the same speed, wouldn't it? Nothing to do with traction.

TheBlacksmith · Posted: Tue Nov 11, 2008 6:02 pm

Traction tyres are a bodgy fix for a cr*ppy mechanism. Usually one where the locomotive has a limited number of driven wheels. Also, traction tyres wear out and perish, leaving you with nothing.

The real answer to this problem is to bring the grade back to a practical gradient. I have done the calculations, and your grade is closer to 1:16.5, which is way greater than it should be.

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1555 · Posted: Tue Nov 11, 2008 9:39 pm

Parksider said <My track rises about 85 mm in a curved length of about 1400 mm. >
It seems that everyone has forgotten it is on a curve.

Whats the radius of the curve ? 18"?, 3 foot?, 6 foot?, is it settrack ? , the drag caused by the curve can be extremely high, specially when compounded by other factors weve not been told about, like wheel composition, metal or smeggy plastic ?, axle type, plain bearing or pinpoint,?, does the rolling stock free roll unassisted, individually, down a 1 in 50 slope? or for that matter, at all?? (1 in 50 is the equivalent of a pencil diameter, stuck under the end of a 300mm ruler, )

If its any help, I had an almost identical problem like this with my first fixed layout, sizes as well, and the board was only 3 feet wide !!
Ya canna stop on the hill an' expect it to work properly from there young 'arry !
The old Triang R55 had almost one pound of lead in it, but it still needed a run up the hill !