It depends on the locomotive and the speed at which you try to negotiate the turnout. I have 2 #4 turnouts making a crossover (I would rather not but that is all I have room for). All of my steam locomotives negotiate the crossover. I have an IHC 0-8-0, a Mantua Pacific (4-6-2), a Bachman GS4 (4-8-4), a Rivirossi Northern (4-8-4) and a Athearn Challenger (4-6-6-4). The only time I have ever had a problem is when the turnout was set wrong .
The big locomotives do not look very elegant negotiating the turnouts, but they do get from point A to point B.
You'd almost have to experiment and see. Keep in mind an engine that will go thru a No.4 OK might not go thru an S-curve created by two No.4's together. If you are using a track line that has No.5 turnouts, that might be your best bet. I believe the closure radius for a No. 5 is 26" in HO so should work OK even in an S-curve for anything except maybe long cars with body-mounted couplers like 80' passenger cars.
I haven't has a real layout in about 10 years, but I was operating with 18" minimum curves and Atlas Snap Switches and AHM equivalents when I did. Most of the steam locomotives I had at the time had absolutely no trouble. While most of the larger steam were Mantua 2-8-2s, I also had an AHM/Rivarossi NKP 2-8-4 and the N&W 2-8-8-2. Maybe it doesn't look prototypical, but never having had the room for anything more than a 5' X 12' layout, I had to go with what was available to me.
As far as blind drivers go, that is one or more drivers with no flanges, that depends on a given prototype. Over the years, many MR reviews have referred to the prototype of a given model having one or more drivers blind to match the particular prototype,and TRAINS magazine has had pictures of x-10-x locos with either a leading or trailing driver set blind, or a middle set blind. I vaguely remember a reference to at least one loco, possibly a larger 2-8-2, actually having both inner sets blind.
The layout I am planning right now will be about 6 or 6.5' wide by 13' long, and will probably have at least 24" mainline curves and #6 switches. I kitbashed a couple articulated passenger cars from Athearn kits, and the 3 unit diner need at least a 23" radius. I also have an assortment of 85' cars, and even a couple old Ambroid 90' Tobacco Hogshead cars that just don't look good on 18" radius curve, especially if coupled to something else. I don't think I have a steamer that needs anything more than 18".
markpierceMisterBeasley My Proto 0-6-0 and BLI 4-6-4 Hudson both operate on my layout with snap switches. I believe those snap switches are actually something like #4.5s, and doesn't their curve extend through the frog unlike U.S. prototypes? Curved frogs create real nasty s-curves at crossovers too. Mark
MisterBeasley My Proto 0-6-0 and BLI 4-6-4 Hudson both operate on my layout with snap switches.
My Proto 0-6-0 and BLI 4-6-4 Hudson both operate on my layout with snap switches.
I believe those snap switches are actually something like #4.5s, and doesn't their curve extend through the frog unlike U.S. prototypes? Curved frogs create real nasty s-curves at crossovers too.
Mark
Snap switches are Atlas brand with a continuous 18" radius for the diverging leg. They match Atlas 18" curved track.
The Atlas #4 is actually a 4.5 but otherwise a normal turnout, the advantage being they don't have the closure radius of 15" of a true #4.
Enjoy
Paul
Unless planning on running only small B-B locomotives such as an SW7, S-3, Heisler, and those with no more than three small-drivered axles and 40-foot-long cars, I avoid #4s. Number 5s are good for medium-sized locos and 50- to maybe 60-foot long cars. Number 6s should handle most anything, although I'd go with #8s at crossovers if running larger articulated and conventional locomotives, full-length passenger cars, or, heaven forbid, modern automobile carriers. Locomotives with either or both four-wheel leading and trailing (the worst) trucks are the greatest offenders because of their long overhang
Mark, for whom railroad-time stopped in 1956.
My Proto 0-6-0 and BLI 4-6-4 Hudson both operate on my layout with snap switches. To take the 18-inch curves, the Hudson has a dual-position mount for the tender drawbar, so that they can get the extra separation needed for the tighter curves. While these engines take the turnouts without a problem, the layout is designed so that any snap switches on the main line, where speeds are higher, are oriented so that the trains go through the straight path only.
It takes an iron man to play with a toy iron horse.
Speaking of HO scale, if you want to run Alleghanys, Santa Fe 2-10-4s or any high-drivered loco with three or more driving axles, #4 turnouts aren't a good idea.
If you run low-drivered 2-8-0s, 4-6-0s, teakettle tank locos or the Mantua/Uintah 2-6-6-2, #4 turnouts won't give you any trouble.
Manufacturers have compromised large locos with blind drivers the prototype never had, sloppy axle side play and tender drawbars two yards long to enable their products to take 18" radius curves and #4 turnouts - but the result is seriously ugly. Those locos need wider curves and #6 (at least) turnouts to look and act comfortable.
Why did I single out the Mantua 2-6-6-2 as a loco that would be suitable for tight curves? Because mine will take a 300mm (<12") radius, and is well content on 350mm. Of course, the prototype was designed to take curves of 68 degrees. (DON'T try this with a N&W Y-anything!)
My private railway uses #4 turnouts and T-I-G-H-T curves to claw its way up a steep and winding canyon, but is restricted to small locos and short cars. My Class 1 is built to much more generous standards, with #5 turnouts or larger and curves of corresponding radii. JNR locomotives, DMUs and long goods wagons are NOT welcome on the TTT - most of them would derail going into the first serious curve.
Chuck (Modeling Central Japan in September, 1964)
It would depend on what steamer you want to run through it. Some are limited to 22 inch radius and larger. Some steamers I have say they can go around an 18 inch radius but derail on a 22 inch. I have six axle diesels that derail before the 2-10-4 does. Then again it looks toylike and I would limit the small switches to the yards and industries handled by switchers and leave the big power on the mains and heavy branch lines.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
I've been told to run no smaller then a #6 turnout when running steam engines, excluding smaller locomotives without a leading truck assembly 0-6-0, 0-8-0 etc. Is this true or it it just speculation or misinformation?
Thanks