OK so I'm thick. But please help me.
How do you calculate the maximum safe height in a slope for 4 ft over the ground in N Gauge.
Regards
GKman
Welcome in GKman :wave:
Maximum safe gradient is largely dependent on the trains going up it - a six-axle diesel loco might happily pull a dozen coaches up a 1:20 (or 5%) gradient, whereas a little steamer may struggle to pull an autocoach up something half as steep! ;)
What trains do you intend to run? Modern or steam? Short trains or long?
Whatever the stock, calculation is probably easier in metric as otherwise you're dealing in fractions of an inch. 4ft is approx. 120cm, and usual practice is to aim for a gradient of at least 1:40, or 2.5%. That means for every 40cm travelled the height goes up by 1cm (hence 1:40, or "1 in 40"). Taking these assumptions the maximum height over 4ft (120cm) would be 3cm :thumbsup:
As said, it is possible to go steeper but at the risk of having to limit what trains are used on it. Sometimes the easiest way is to set up a test piece using a length of flexitrack and try all your trains on it at varying steepness to see what starts to slip first and at what angle :)
Paul
Not sure what you mean by "safe"...
....But if you mean max incline that locos can climb with a reasonable load, based on other discussions on this site, it would seem 2 to 3%
To work this is out (sorry going to use mm as I am metric) and saying 2% cos its easier...
2% = 2 / 100 or "2 in 100" which is the same as 1 in 50. This means for every 50 mm along, the track can go up 1mm into the air.
Converting 4ft into mm gives 1219mm (rounding down)...
...so at 2% gradient, this means (1219/100) * 2 = 24.38mm over 4ft (or just under 1 inch)
So, with your space, you can raise your track about an inch across the length of your 4ft length.
Hope that makes sense.
Skyline2uk
Let me add my experiences when I was a noob. I bought a Woodland Scenics Scenic Ridge. I love the layout overall, but they had 4% grades! :veryangry: I had no idea at the time as a novice what that would mean. Oh, yeah, the steepest part of that grade is on a 9.75" curve. :veryangry: This is a look up that grade.
(http://i163.photobucket.com/albums/t287/scottmitchell74/Train%20Stuff/P1080799_zps9cc788f0.jpg) (http://s163.photobucket.com/user/scottmitchell74/media/Train%20Stuff/P1080799_zps9cc788f0.jpg.html)
I've had some very nice Atlas models that simply couldn't make the grade, as they say. I've had to trial-and-error my way to a small roster of Locomotives than can pull a decent rake up that grade.
Lesson - If I could do it over (and when I make a new layout) my max grade will be 2%, and if I can design a bridge scene without a grade at all? Even better.
I don't know what Woodland Scenics are thinking with those 4% risers.
I would go with the above advice and ideally would try for no more than 2%. Whilst this does not seem much at all if you need to get one track level above the other so it can pass over it then try to design the layout so the lower track descends the same percentage as the other track rises. That way you can achieve the same as a 4% gradient with neither track being greater than 2%.
Sorry if this is stating the obvious. :worried:
It does mean extra work in designing and construction but will be worth it.
Steve
Quote from: GKman on February 17, 2014, 08:36:05 PM
OK so I'm thick. But please help me.
How do you calculate the maximum safe height in a slope for 4 ft over the ground in N Gauge.
Regards
GKman
Hi GKman,
I have a coal drop, which is 2.5mm high, 68mm long slope + 3-4 waggon length level. See photo in "what your modelling at the moment" Nawton Station.