I’d like to have 6 Axle diesels on my shelf/switching layout.
What’s the minimum radius and turnout Frog number I can safely use?
(right now my hypothetical plans inlclude a 28" minimum and #6 frogs)
A lot depends on how fast you plan on going. You could probably squeeze a 6-axle diesel through a #4 turnout at yard speeds, and maybe a 20-24" curve when spotting a car at no-breakum-egg speed. Try setting up some curves at home and see how tight it will go at slow speeds. Perhaps 15" radius curves are possible at a creep–I don’t know, I don’t have any diesels bigger than a GP-7 (which handle 12" curves, btw.)
Having too-tight curves can provide operating challenges, too–perhaps your big 6-axle diesel can’t make that tight curve into the industrial park, so it has to set out cars for a 25-ton GE switcher to shuttle into the squeaky parts of the layout. Limitations aren’t always a drawback…puzzles aren’t fun if they aren’t a challenge.
A SD40-2 should be able to go around 18 radius curves jts fine. But the larger 6 axle locomotives like Dash 8,9 and SD70 locomotives may derail the car behind the locomotive.
ShaunCN
I use Athearn blue box 6 axle SP daylight engines (PA-PB-PA), w/o consist, to test newly laid track. It works on my 20" return loops with #6 TOs. The tests start at creep speed and the fastest test speed I’ve done with my MRC Tech II DC set up is at 60-65%.
I use Kadee #5 couplers.
I’ve run Athearn Dash 9s and AC4400s on Hornby 3rd-radius curves - I think these are about 315mm radius, they’re a little under 2ft radius anyway. The locos run fine - I know they’d look a lot better with gentler curves but unfortunately I don’t have the space at the moment!
One thing about planning a shelf layout. Try to make sure that all headshunts and passing loops are long enough to accommodate your longest loco and car. The longest I had while constructing my layout was an SD40-2 and a Husky Stack, so I designed the headshunt tracks to be able to handle this. Unfortunately, I’ve since bought some superliners and a hicube box car, so I think I need to add a small extension!
You can safely use am 18" radius curve. I have one on my layout. It’s in a tunnel so no one is going to notice. I won’t go smaller than 18" though. The rest are 22"
I have an Athearn C44-9W, no problems.
I also have 9 Athearn SD40-2’s, again no problems.
I have a friend that brought his Rivarossi 4-6-6-4 over. No problems on the curve.
It didn’t look that great, a large over hang, but it made it.
If you’re using 28" radius curves, you can pretty much run anything you want.
As for turnout’s, go as least #6 on the mainline. If you use a smaller turnout, you’d have to slow your train down quite a bit to ease the possibility of de-railment.
Gordon
For sure, The Atlas SD 24 & 35 will run on operate on 18" per Atlas.
The Athearn SD-2 will
According to MR reviews.
Lifelike DL-109, 15"(22" is better)
Lifelike SD60M, 18"(24" is better)
Kato SD80MAC, 18" w/o cars(24" recommended)
Kato SD70MAC, 18" w/o cars(24" recommended)
That’s weird that Atlas lists the SD24 and SD35 as not making 18" curves as I have four and they all make it without issue on my old layout, but they are the older Atlas versions made in the 80s.
Warren
OK, now you’ve all got me considering making a return loop for my switching layout, so I can have continuous running on the “loop” while doing some switching, or for just “letting them run”.
The broadest loop I can do is 17.25" radius. From what everyone has said, it sounds like I’ll have no problem with 2 axle diesels, but will be pushing it with 3-axle units. I guess worst case scenario, the 3 axle units won’t get to make the trip around the loop (which isn’t going to be scenicked anyway).
It ALL depends. For example a stock Athearn SD40-2 will do okay on 18" radius, BUT if you put a scale lenght RPP frame under it, and scale steps, etc, it will do maybe 28" min. As you add more prototypical details to your locomotives, the larger radius they will require.
Brass locomotives typically require much larger radius because of thier more prototypical details.
Walthers had an issue with a caboose not long ago, the steps where scale, which greatly limited the truck swing…
I suggest you stick with the 28" min and #6.
I have a pair of older (Late 1980’s) Con Cor SD24’s They were run on the Store Owner’s HO layout with 18 inch radius together without any problems even with slightly bending to 15" in that one spot and dirty track (Under construction) #4’s too.
These 6 axle units will be doing alot of my local work getting into and out of tight areas while I leave the yard to a P2k 0-6-0 and a Athearn Cow and Calf. I think the SD24’s were a good choice because they did not look bad as some of the bigger engines may.
With that said, most of my Piston and Spark Power will be covered wagons (F units) and a few smaller 4 axle units run in MU (Such as Baby trainmasters etc)
Hope this helped.
Lee
I don’t know what your layout looks like but have you thought about putting “reversing tracks” on your layout rather than return loops?
Here’s what I designed for trainboy. It has reversing tracks vice loops for continuious runing.
http://members.cox.net/dbhuff/images/Alex%2003.gif