When I built my layout the first thing I did was make three cardboard templates of various radii - 18", 21" and 24". The templates were the same width as the spacing between the rails of HO track. I then drew a single pencil line on the base platform to indicate the proposed centerlines of the track. Where there were curves, I used a string compass. I used the templates to set the best curves for the space. Using the centerlines I laid cork roadbed, again using the templates to maintain a proper radius. Now the problem.
I tried to use a minimum 21" radius on the entire layout. Is that too tight a radius for triple axle engine, such as an EMD E8? When i set the track I'd tap it down so the joints were even, and using a push stick, I run an empty, underweight car to test the track. I figured an underweight car would be more likely to jump than a properly weighted one.
Thank you.
It depends on the model and the manufacturer. A long diesel like an E-8 might need a larger radius curve than a shorter engine like an SD-9, even though both have three-axle trucks. Also, one manufactuer's E-8 might be built to take 18" radius curves, while another maker's E-8 might require 22" radius curves. (Note that at one time most all HO equipment was built to take 18" radius curves, but in recent years a lot of manufacturers are recommending 22" radius curves for their products.)
Even if you're using cork roadbed and flextrack, it doesn't hurt first to do a test with your equipment by getting some "click track" (like Kato Unitrack, Bachmann E-Z Track, or Atlas True-Track) in various curve radii and see how it works. Sometimes a piece of equipment like a large engine can go around a tight curve by itself, but doesn't work so well when coupled to a car or another engine.
I have a dozen E7s and they will negotiate 18” radius in AB pairs easily. I have Atlas #4 turnouts in my yard and the E7s will go through a pair of #4s in a tight S configuration.All my E7 ABs are drawbar connected and no problems. My mainline minimum is 24” and no problems at running speed towing 11 over weight passenger cars.Early on I had some Proto PAs that had problems negotiating the Atlas #4 S curves and after many dealings with Proto I gave up and sold them. My Athearn PAs work OK. I also had several Proto E7s, E8s and E9s that had no problems. Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
Make simple convex and concave curve gauges to the inner-rail curve radius (not the 'nominal' which is to the centerline) with a trammel and knife using a piece of suitable card stock or similar material. Turn the engine over and fit the gauge to the flanges for both curve directions -- this will show both inability for the trucks to pivot (e.g. if gear towers bind) and any lateral issues with the truck wheelbase or lateral accommodation.
I've got a Proto RSC-3 that's a 6-axle version of the RS-3 made for lighter trackage to better distribute locomotive weight. It works just fine on 18 inch curves.
On the other hand, I have an SD9 (I think) I picked up used at a train show that doesn't like 18 inch curves. It's in a box somewhere.
It takes an iron man to play with a toy iron horse.
I can only speak from my experience.
My only six axle diesels are a Proto 2000 SD7, an Athearn Trainmaster, two Athearn PAs, and two Proto 2000 E8s.
These will all negotiate a 22 inch radius curve with no problem and no modifications.
-Kevin
Living the dream.
RealGomer. Do you have space for slightly larger curves? If so, you engines might stay on the rails on tight curves, but they might be happier on something a bit broader if possible. And what about freight and passenger cars. Long rolling stock likes broader curves if you can spare it.
Rio Grande. The Action Road - Focus 1977-1983
Since the question is asked about 6 axle diesels in general, I can add that my Athearn BB SD40 and Fairbanks-Morse Trainmaster derailled on my 18" curve layout. My new layout has 22" curves - that they can handle.
Simon
Another thing to keep in mind when using flextrack on a layout with sharp curves is the curve radius has to be exact. If you have a slight kink in the track so the 21"R curve briefly goes down an inch or two, it could be causing the problem.
Kato Unitrack has a curve that's 19-1/4" radius, I'd maybe buy a 4-pack of them and try your engine(s) on that. If your engines work on that, then probably your 21"R curves have a kink in it somewhere.
p.s. Kato also makes a 21-5/8" radius curve, and their electric No.4 turnouts are built to match that curve...might be an option for your layout?
I'd say that it depends on what locomotive the model is, who made the model, and when it was made. I have a 22" radius mainline, and a spur with 18" radius, and all 14 of my triple axle diesels run great on the 22"s, and they also do fine on the 18"s. I also have a quad axle diesel (Athearn Blue Box DDA40X) that does fine on the 22"s and can even take the 18"s. It looks a bit odd, but it can do it. If it helps, my triple axle engines are: Athearn Blue Box ALCO PA1 and PB1, Athearn Blue Box SD40-2, Athearn Blue Box SDP40, Athearn Blue Box SD45, Athearn Blue Box FP45, Atlas Yellow Box SD24, Bachmann Spectrum GE Dash 8-40 CW, Bachmann SD70ACe, (the SD70 is new) KATO SD90/43MAC, Proto 1000 FM Erie Built, Proto 2000 E7A, Rivarossi U25C, and a ScaleTrains GE ET44 GEVO. (The GEVO is about 2 years old). Hope this helps.
Hello All,
On my 4'x8' pike, the "mainline" is made up of 15- and 18-inch sectional track that form asymmetrical curves.
I have successfully run six-axle diesels and 85-foot passenger cars over this trackage.
Yes...
These locomotives and cars can negotiate the tight radii trackage and an "S" curve created by four Atlas Snap Switches.
However, they appear more toy-like than a model railroad.
As has been said many times in these forums:
"It's your railroad, run it how you want."
I will also add, "...And make it fun!"
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
I use Kato Unitrack, with the smallest curved pieces having 19.25" radius.
My six axle locos are SD7/9, SD35, U25c (Rivarossi), RSC2. Also have a couple of Bowser c430's, which are as long as the 6-axle engines.
All of them negotiate these curves without problems...
wjstixKato Unitrack has a curve that's 19-1/4" radius, I'd maybe buy a 4-pack of them and try your engine(s) on that. If your engines work on that, then probably your 21"R curves have a kink in it somewhere.
I 100% agree that test running your equipment on a Unitrack Obstacle Course is the best way to know that the problem is on the layout.
Also what are you pulling. I use 18" radius curves and had no problems but when I was messing around to see what the longest reain I could pull was, the gremlins showed up. Now it dosn't mater for me as I built the layout for short trains but just goes to show you that you have to fiqure out what you want to run also.