Would like to do some sort of mountain/mining line - possibly using switchbacks. I've browsed online and found some models using switchbacks, but very little in G scale. Anyone have any pointers on this? Perhaps some good layouts or other references that could help with planning?
Switchbacks
- Thread starter jtilleyx
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I can't remember the actual video but on youtube is a video of the longest switchback rack railway in the UK - G scale and LGB I think.
Geoff
If you want to see some more on how switchbacks work look at some YouTube vids of the Darjeeling Railway. Plenty of switchbacks and spirals to get your teeth into. Only issue I would say is to plan that the points in each switchback be accessible. A proper switchback will have at least 2 points so that the train continues engine first the same way. Some may double up on that.
Wow - very impressive. Any idea how steep of grades he is working with. Several of the switchbacks have to be significantly over 4-5%. On the video, some look as if they may be 20% or more. I've been trying to keep under 4% - I know some railways historically pushed past that, but not in double digits. For mine, while I would like to keep within some realm of reason, I am not overly concerned with true to scale. The most extreme I would need is 15%. I have a 30 inch drop over 15 feet - if I can make this, it opens up endless possibilities. What is the grade limit to push these G scale models. I'm sure there is some variability given length/type of cars: I will be using Piko Mogul 2-6-0 with only 3 or 4 cars for quite a while
Without rack you would need a loop or zig-zag (is that what you mean by switchback?) to climb 2 1/2 feet in 15 feet. That's average 1 in 6 in motoring terms, and the maximum incline would be more to allow for transition from level at both ends.
As Dave says that guy uses Rack a completely different application to attack the issue of hill climbs.
Zig zags and Spirals should work on normal accepted gradients and probably 1 inch in 20 or at worst 16 should work with small trains. Here you then come to the logistics of your site and the trains you wish to get up those gradients, zig zags will help for longer trains up impossibly sloped gardens given easier gradients say 1:30 or thereabouts on those zig zags. But of course your siding lengths at the reversals of the zig sag needs to allow for the longest train, plus a reasonable run between them to make it worthwhile to put them in in the first place to achieve some height.
Lots to think about, a good way to work things out is to use a piece of squared paper to measure rise in distance. This can be at differing scales of course and the following may give you an impression of what I am talking about. Not too well drawn with freehand, but left you have rise per inch for each square, right length of run is a Yard (36 inches) per 2 squares.
Thus in this instance arriving at the zig zag we have a rise of 3 inches in 3 yards at 1:36. Then the reverce siding and another rise after reversal of 3 inches in 3 yards again. Setting off the other way another 3 inch rise in 3 yards gives us a rise if 9 inches just 3 yards of length. Of course this is a simplistic view, but the method works for all types of gradient planning.
You're right, there's very little that I've seen in this scale using switchbacks - probably because there's the LGB rack system which can accommodate much steeper gradients.
IMHO it's one of the few areas that can be translated across the scales, because the principles of track adhesion (limiting the steepness of the gradient) and the length of the spur at each switchback (which is entirely reliant on your proposed length of train) are common.
The other constant, again across the gauges, is to ensure that the points are laid on the flat, so the gradient must start from the next piece of track.
What I don't have any experience in, and there was another thread on this quite a while ago, is the amount of vertical curvature that you can apply to G Scale track at the top and bottom of each incline - this will of course impact on the space required
Thinking about it, it'll require a lot of space
So, if I understand correctly, a "rack" system is a cog line - uses teeth to lock in as it moves forward. That would make much more sense. Never considered it. Have a feeling I know the answer, but going to ask anyway: is there a way to combine these 2 systems? Assuming rack uses specialized track - can it be used to replace sections of regular track. Can regular loco's/cars be modified to run on both?
If I worked it out correctly (thank you dunnyrail), I can make a 2 1/2 ft incline over 15 feet. However, I pushed the grade to 4-5% and only have about 2 1/2 ft on the "tails." Given loco is 22.5 inch, not very useful. I used about 9ft for each run to gain elevation. I guess that could be decreased and add more zig zags and decrease grade - what a pain in the butt, I need a cog
If I worked it out correctly (thank you dunnyrail), I can make a 2 1/2 ft incline over 15 feet. However, I pushed the grade to 4-5% and only have about 2 1/2 ft on the "tails." Given loco is 22.5 inch, not very useful. I used about 9ft for each run to gain elevation. I guess that could be decreased and add more zig zags and decrease grade - what a pain in the butt, I need a cog
Attachments
LGB make one or two rack locos as models of European prototypes - I'm not exactly sure which ones are currently available as I don't do European. There are also some more expensive KISS rack locos if you have a friendly bank manager
The big idea is that if you use a rack, you're not going to need a switchback, because rack lines will run much more steeply than normal adhesion lines.
That's the theory
LGB track is the same, the cog rail runs along the middle with clips to hold it in place. It can be clipped in place on straights and curves, even R1 curves just about. You can have plain adhesion track and then put in rack when the inclines start. There are steam and electric cog locos from LGB, mostly based on Swiss narrow gauge railways. The steam ones look cool as the cog mechanism comes into play when it hits the rack sections. Non-rack locos will run on the same track. Look on YouTube for videos of LGB Ballenberg rack loco.
Definitely a case of "because I can"! That must have taken some hard work just secure the track base
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My memory of the Diggle Valley Railway was that they had a massive height differential over the area of the garden railway.
There are a limited amount of Rack Locomotives in the market, LGB in particular do and Electric 4wheeled box cab, an 0-6-0 and a recent very expensive 0-8-0. Other than smaller manufacturers KISS has been mentioned that is your lot. The prospect if converting another loco to rack operations would be tricky at best as the locomotives have gear wheels on axles that are not a standard fitting. Here are the underneath of the 2 locomotives I mentioned, not on the steam there are 2 sets of cogs the other one is to move the counter rotating rack valve gear. This of course only works on rack fitted track as would the prototype. I also had to fit up the steamer with additional power pick ups as there were so few plungers to give anything like reliable running.
We installed a Rack at my friends line and to be honest found the running on the line was awful, very bumpy going down the grade (though the real thing can suffer rom this) and couplings riding over each other causing derailments both ways as we used to push the trains up hill.
I can see why you would find the zig zag a bit of a pain, but so much fun to operate. Another option may be a spiral of as they call them over the pond a helix.
AustrianNG
- How tight of a radius are you meaning with "hairpin"? Tighter than 24" radius? If so, guessing would require flextrack? Everyone has been very helpful on here. Just trying to make sure I at least consider all my options before startingDunnyrail - modifying a non-rack loco would be beyond my level for now.
I initially considered a helix, but the area needed is constrained by radius width (max is about 4-5 ft). I fear that there may not be enough headroom (height clearance between loops for loco to pass). If I done my math right, using a 24in radius and allowing for 9 inch clearance, I would end up with a 5.5% grade. If I can squeeze in a 60in radius, will result in 4.5%
It seems switchbacks (zig zags) are most optimal solution...….. Although, perhaps a little unorthodox: an elongated helix may be a good alternative? More of a stacked oval.
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I used R1 and R2 LGB curves (600 and 750mm radius). The average gradient was around 1 in 24 to 1 in 40.
Once you have tight-curves, and gradients together.. The drag, and load on your loco's becomes much greater. - This will mean they pull more current, and everything will wear at a greater rate.
If the consist become too big, (hopefully) the loco will slip (wheelspin).. In severe cases, if the wheels do not slip, then something will fail. - usually electronics, or burnt-out motors..
By all means try-out a simple oval of track, if you have a flatish slope you can put it on.. But be aware that 'we' are running on radii that no real railway ever would.
If the consist become too big, (hopefully) the loco will slip (wheelspin).. In severe cases, if the wheels do not slip, then something will fail. - usually electronics, or burnt-out motors..
By all means try-out a simple oval of track, if you have a flatish slope you can put it on.. But be aware that 'we' are running on radii that no real railway ever would.