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Short Steep v Long Moderate Gradients

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Mon 2nd Oct 2017, 12:48pm
Short Steep v Long Moderate Gradients

This winter I'm planning the extension to my garden railway to the higher level of my site, the height difference is approx 5 m. but might be able to reduce that to 4 m Max length of track to reach the highest level is about 200 m. Would a continuous 1 in 40 (ish) be best or one or two steeper gradients say max 1 in 25 then leveling out be preferable? Whichever is chosen there is earth moving to do which presents no problem as machinery is owned and on site,
 

Replies To This Post

Mick

Joined: 1-01-89

Topics: 7

Replies: 114

Posted: Mon 2nd Oct 2017, 6:28pm

In my experience the long moderate incline is definitely the best.
 

Bill

Joined: 22-05-03

Topics: 17

Replies: 30

Posted: Mon 2nd Oct 2017, 10:54pm

If the width of the site allows perhaps climb with low gradients with return loops on the ends. The appearance then zig-zags when looked at from the side. Depends on the topography of the site really.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Tue 3rd Oct 2017, 1:50pm

Thanks Mick & Bill for the replies, I get the feeling that long and moderate constant gradient will be best and that is achievable. This proposed track will be a 'stop end' branch line there is not enough room to incorporate a 180 degree turn at the terminus in my chosen 30 ft radius nor even on a reduced radius of 25 ft the minimum for the bigger steam loco There is however room for a passing/run round loop to any length desired.

As a matter of interest the lower level track has a max gradient of 1 in 53 but that's entirely on a 30ft radius for a 180 degree turn and incorporates 20 m of it as a level crossing. My site has (and is) indeed been very challenging with it's variations in levels and the need to incorporate two level crossing for the entrances both being constructed to accept heavy lorries driving over them.

 

Xz

Joined: 1-01-92

Topics: 17

Replies: 244

Posted: Tue 3rd Oct 2017, 7:00pm

Don't forget you can gauge-widen to allow tighter turns.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Tue 3rd Oct 2017, 7:53pm

Thanks X2 for your reply. I've no practical experience but have heard about cheating a bit on minimum radius by gauge widening beyond the norm, how much extra width beyond that norm and what sort of wheelbase to radius ratio could you achieve? My railway is entirely private and light running only
 

Xz

Joined: 1-01-92

Topics: 17

Replies: 244

Posted: Wed 4th Oct 2017, 8:42am

There are no hard and fast rules, do your own thing. Another 1/8" is not out of the ordinary.
 

franksidebottom

Joined: 1-01-95

Topics: 4

Replies: 28

Posted: Wed 4th Oct 2017, 3:49pm

Memories of visits many years ago to the steeply-graded Jumbles Valley Railway prompted a search (in the archive section of this website) for a very interesting article by the late Eric Doyle (former Chairman of our Society) where he describes the construction of a turning triangle at the end of his branch line, offering an individual solution to the combined problems of limited space and steep gradients. The article, in issue 85 of the 7 ¼” Gauge News, summer 1998 pages 39-42, may provide further thoughts in the context of this thread. Happy reading!

As for gauge widening, I added 1/16” to my own railway’s 28-30’ radius curves. All has been well with wheelbases up to 24” (at modest speeds) although I am unable to say if the result would have been significantly different if gauge widening had not been applied or if longer wheelbases had been tried.

To cap it all, a certain character (well-known on this forum) once expertly and surreptitiously ‘gauge-widened’ some of these curves further by an unconventional method – before deciding it was high time to re-profile his loco’s knife-edge wheel flanges! At the time I even thought of collecting the resulting swarf in the hope of obtaining a good price at ‘weigh-in’! The incident has at least enabled the banter to be kept going for years! (LOL).
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Sun 8th Oct 2017, 12:09pm

Thanks Frank for the heads up re issue 85 and the jumbles Valley Railway. I like the triangle idea but in my case the high level terminus is narrow and it's at the top of a steep bank 5 m above the lower level, it would mean one leg of the triangle going out on a pier at the 5m height. Big supporting trestles would have to be constructed and installed to make this possible. As an alternative I had considered a passing loop as it doesn't require much width and at the terminal end of the main track installing a turntable sufficient to accommodate the longest loco, OK you have to stop dismount the loco and physically push it around the 180 degrees but that's not too onerous for a private (non public) operation

I love the suggestions on here and it's the first time I've used the archive a huge fount of knowledge.
 

franksidebottom

Joined: 1-01-95

Topics: 4

Replies: 28

Posted: Mon 9th Oct 2017, 11:51am

Prompted again (with thanks for XZ's help) to go delving back into the News archives, it is well worth checking out John Chetwin's inspirational three-part article 'Where There's a Will' which can be found in issues 124 Spring '08 p7, 126 Autumn '08 p23 and 128 Spring '09 p6 respectively. I understand the railway is no longer extant, but the article remains a testament to a unique achievement, fuelled by powerful enthusiasm. Happy reading!
 

Phil

Joined: 1-01-93

Topics: 0

Replies: 4

Posted: Fri 3rd Nov 2017, 9:10am

From my experience of buidling a modest garden railway and planning for a second. I would suggest trying to keep the curves as level as possible. A greater brain than mine would be able to express it more scientifically but any curve adds drag to the train.. To guess at the figures... a straight 1 in 100 would be the equivalent of,say, 1 in 50 on a curve.

So with the sort of gradients you plan if you could keep the curves flat it would help greatly.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 27

Replies: 91

Posted: Sat 4th Nov 2017, 10:05pm

Thanks Frank for the alert to the articles about John Chetwins railway, what an incredible task!

My site Phil is difficult with it's access problems and level changes inside the two entrances I need m 180 degree turn over 40 m of track at a 1 in 54 gradient then some ongoing curved track at a lesser gradient, I'm afraid it's the nature of the site. i Have however opted for standardizing on 30 ft (9.14 m) radius curves even though the loco's will handle lesser

 
 
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