minimum curvature.

S

Steveford666

Women, engineering, photography, guitar plaoing, s
I have bought a couple of Bachmann Annie locos. I am laying out the route f the track. But what puzzles me is that while I would like to keep the curves to a minimum radius to make the straight runs as long as possible, what would be the smallest bends these locos would go round. Okay, I know I can buy some Peco small radius track, but this would be a waste of money of the locos will not go round them. Any ideas folks?
 
I would say go for R3 equivalent, which is 8 ft diameter, as a minimum....
 
Look at it the other way around.

The straights are just there to join the curves together :thumbup:

Go large whenever you can :bigsmile:

As Gizzy says, view 8 ft diameter as a minimum. The 4-6-0 has quite a big overhang at the front.
 
They do go round R1 curves (my trailer layout is all R1 curves and points) and I have some curves (and all points at the moment) on the garden line. Reverse curves can be a problem (I weighted the pony trucks on mine) and the original Bachmann radio controlled battery big haulers don't like R1 at all. I have five big haulers (track powered) and I think they are great locos for the money.

Mick
 
as always a question of what is possible against what is useful.

the annie goes through very sharp curves, i think to remember a youtube vid where it was on a housfloor-layout on something between R1 and R2.

But dont do that.

Three major reasons:
1.) the sharper u go, the worse is the loco-performance: traction, derailment, slowing down etc.
2.) the sharper u go, the worse it looks.
3.) using the R3 as the others said always allows to go to the 1:20,3 community with the nice rolling stock of AMS or Spectrum.

Greetings

Frank
 
].... and here's a piccy (I hope)
c59595122c0a43f3a7c0e9854b920c46.jpg
01287a4f1c874b21838694408b607f64.jpg
 
now don't ask me how I got three of the same in there!
Gone back in & deleted two.
 
I have two annies, and have no trouble running them round radius 1 curves, although i don't have many radius 1's joined together, i have mixed mine so i have say 1 radius 1 then a couple of radius2's or radius 3's or a gentler curve first ie radius 3 then one or two radius 1's then come out on radius 2's or 3's, doing it this way may be wrong, im sure some of the more experienced centralists will put me right, but this method works well for me.:thumbup:
 
Thank you all for the information. I shall be going as large a curve as possible. I need a few places where the track will have to thread between the bushes in the garden. I do agree, a sharp curve doesn't look too clever, but where needs must and all that. It will allow me a bit of room to have nice sweeping curves after the junction where the single line will split into two. One line will go up and the other will stay level. The higher one will be on a trestle bridge type thing and will curve over the top of the lower line. The problem is our back garden is not the size of the Yorkshire Moors. I was going to do an HO gauge Austrian railway with OHL equipment. But decided G gauge will work better. The HO set will go into the loft.

Steve.
 
Hi Steve,

so the trestle will be the right decission for sharp curves on a higher level. IF u need a curve that is sharper than R3, try to reduce the diameter (radius) step by step.
Never go from straight into the sharpest section. That cuts of the biggest problems.

Ever use a straight section between two "s-shaped" curves, that includes switches in parallel-tracks, too.

With switches, take the big radius THERE, its much more important. If tracklength in a staion becomes too short, better reduce the number of tracks and use high quality, eventually curved switches.

For tracklining, take a look at the picture-section on my site (link below)


Greetings

Frank
 
Points will be to a minimum of radius 3. I don't want to have to clamber over the bushes to re-rail the train. The radius 1 will be at the bottom end. I shall mix it with radius 3 curves. (or gently curved flexi track). There will be a short straight and the junction and the trestles. I can't get rid of the buhes as one was bought by my late mother and the others for our wedding anniversaries. All these (And the rape vines) are on the left hand side of the garden.

Total space I can use is 20 x 20 feet. That does tend to make things tight. So everything has to be crammed into that space. The station will only have one track and platform. The double track will join up before the station and drop to the front end of the garden.

I do like your bridge and trestles in alliminium, Frank. As I will have to have a removable section, this seems the answer.
 
Thanks everybody. I looked at the matter of the curves and decided to ease out the curves into an easier bend on at the bottom. I will take photos as I go on and post them when finished. I can do it when the shuttering comes down after the concrete has set. The reason I eased the bends out was to make it easier for the train to start the climb that is imposed by our garden. I wouldn't say it's steep, but I am looking for G scale mountain goats and Sherpas. :bigsmile:

Steve.
 
Putting down the concrete for the new curve I realised what I was doing was wrong. I should do what the railways do. Cant the rails slightly. The outside line should be a quarter inch or so to make a higher speed curve of it without the bed looking ridiculous as the train rounds it. I will have to wait for the foundation to set and use flexitrack on the curve. Once out of the curve, through some points and onto trestles, thankfully.
 
but u know steeve, doing that means to stop at least with 90 degrees.
Therefore u need a VERY high speed, NEVER stop in the high curve... :D
But: using a 90 degree "cant" takes the whole problem with curvature completely away: it has no more effective curve at all! :rolf:


Frank
 
coyote97 said:
But: using a 90 degree "cant" takes the whole problem with curvature completely away: it has no more effective curve at all! :rolf:


Frank
Click to expand...

Hmmm! That's a good space saving tip I never thought of. Build it like a giant hampster wheel and instead of a hampster running to spin the wheel , there will be a train. :bigsmile:
 
I don't to repeat others posts, but the Annie's will go round R1 curves just watch for uneven curves as the Pony truck will jump off. Sold my Anniversary Edition Annie 2yrs ago :crying:
 
Steveford666 said:
Putting down the concrete for the new curve I realised what I was doing was wrong. I should do what the railways do. Cant the rails slightly. The outside line should be a quarter inch or so to make a higher speed curve of it without the bed looking ridiculous as the train rounds it. I will have to wait for the foundation to set and use flexitrack on the curve. Once out of the curve, through some points and onto trestles, thankfully.

Click to expand...


Yeah but..no but..real railways cant curves because railway wheels are slightly conical - the diameter nearest the flange is greater than the diameter at the edge. Centrifugal force on a curve forces the train towards the outside, but track is canted so that the inside wheel travels a shorter distance than the outside wheel. On a real railway, flanges are not supposed to touch the rail. A mismatch between speed, track radius and cant produces flange squeal. Track geometry on a railway with trains going at different speeds is always a compromise - solved on the West Coast by tilting trains that can go faster because they compensate for "cant deficiency" - if the track was canted for 140 mph trains, gravity would overcome centrifugal force for slower trains and the cant would push them against the lower, inside rail - with excessive rail and wheel wear. But model railways use the flanges to guide the trains - we expect that - and at model speeds, centrifugal force is not enough to push the trains sideways. The problem comes from model locos with long fixed wheelbases on railways with very tight curves where the front and back flanges are pretty well bound to touch - and even bind - against the rails. Long wheel base models allow the end axles on a "fixed" wheelbase to move sideways (also used on real five- and six-driving axle locos, but with much more movement on the models). So cant is not really a solution for model railways - except that canted curves look more realistic. Also: with long-wheel based models on tight curves, the front and back go well outside the loading gauge...The answer is that long wheel base models need more generous curves.
 
Looking at some of the models that I have to hand with a magnifying glass, some of them do have tapered tyres and some don't. But I haven't checked the locos as they are safely put away and won't leave until the track is laid. The cant would not be that much. However, by ignoring the moans by her indoors about more of the garden going missing , I eased the track bed of the curve out even more. I ordered the track to do the corner a week ago and it still has not turned up. Mind you, other parcels I am expecting haven't turned up either. (A miniture keyboard for my entertainment centre and other rails bought from Tenmille). :impatient::nail::crying: All I need now is some track and some G scale navvies.

In the early 90's the Lomdon underground experimented with self steering bogies. Whatever they were I have no idea, but they did say they would reduce wear and tear.

From what I can remember, the Beeb showed a diagram that the APT had tyres that looked like worn tyres on ordinary trains. I can recall thinking at the time that it would make it less secure on bends. It was designed by the Concorde design team and what a success that was. From what I heard, the APT was sabotaged so it failed regularly to get bonuses up for the staff who had to ride with it. It caused miore trips out, meant it was not reliable enough for the time taken and therefore was dropped. Shame.
 
For smooth running it is advisable to use the maximum radius your space will allow, I would the think that the approach of using tightest possible curves and long straight sections would present a rather toylike rainset appearance, worth remebring that actual straight sections on full size railways are not that common (except of course on the high speed lines) and narrow gauge lines rarely have many straight sections.

I always try to add some form of curvature to my straight sections to improve the appearance

CLICK on the image to enlarge
 
When I say straight, I meant it would be a little less bent than the corners, (thanks to plants that she who must be obeyed doesn't want removed). I agree with you Steve. To my mind, to have a square railway with rounded corners and long straights comes within the realm of train sets and not models railways.

The lomgest straight stretch on Network Rail is from Barlby to Ferriby. About 16 miles with just a few very slight bends in it.
 
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