Fixed pilot implications on curve diameter?

If it make you think I was running a Williams model E, weaver FA, Williams GP-7 with fixed pilot on 042 and 031 curves.

Andre.

With the original stirrup steps on my WBB E7, I can't negotiate 054 curves.  if removed, it may work.

I have the WBB E7, a 3rd Rail E7, An Atlas GP9, a Lionel GP9, a MTH 0-6-0, 2-8-0, RS3, NW2, a Williams/Samhongsa brass 2-8-2, and a Hybrid 4-6-0 (Weaver brass chassis/running gear and a MTH extended 2-8-0 die-cast boiler).  The 2 E7s are the only ones I would not want to feed a steady diet of 054 curves.  My mainline is 072 curves, the sidings and yard are 054.  All the 4-axle diesels work fine on 054 with fixed pilots and Kadee couplers.

I use Caboose Industries ground throws to set my turnouts/switches, some of them I've had to use an extension wire to move the throw farther away from the track so the pilot can't snag on them.

Dan:

Realistically speaking, if you want fixed pilots on your diesels, you need to be up to at least 36" radius (O-72) curves. If switching to body-mounted couplers on your freight cars, you'll also need to keep track of the lengths of the cars coupled in the train -- i.e., you can't couple a 40-foot car to an 89-foot trailer flat on sharper curves (less than 60" radius/O-120).

Fixing the pilots on locomotives with hi-rail wheels should yield a bit more tolerance with respect to curves, but not a whole lot. If I were a betting man, I'd say the GP30 and GP35 with hi-rail wheels could handle 27" radius/O-54. The F3, E7/E8, PA, C-424, U23B and GP60 are longer locomotives and may have issues (E-units definitely will). Also, You have to make sure the truck side frames clear the pilot steps.

When I went 3RS, I decided to follow 2-rail recommendations and kept scale wheels in place. I tested for 36" radius/O-72 compatibility since we have one on the primary mainline, but if I had experienced problems with that curve, there's an alternate route the trains could take.

Next weekend I'll run a test in the harbor industrial area on the club layout as it's set up with 27" radius/O-54 curves in a couple of areas.

Too many myth sometimes.

here is my E-7 negotiating a 031 curve (my layout is only 4 ft wide so make your math)

So far work for me.

I am waiting for the 2 rails wheels to make her run again.

Andre.

Well if that's just a picture and its not running yet...... If those are body mounted couplers on that passenger car, I can assure you, it won't run on an 031 curve once you try it. Nor will you have clearance if you try to run a train on that outside curve at the same time.

LOL!

run fine on the inner curve and better on the outside curve.

All my engines and rolling stock are tested on the tightest curve obviously to ensure high performance.

The passanger car has a swivel coupler to make it happen, but the rest of the 40ft cars are body mount coupler.

So far work for me!

Andre.

Daniel,

Instead of a duck under, try either a lift out section or a lift up/drop down section (aka bridge).

Here's my drop down section, eventually to be replaced by a bridge that will also drop down (or lift up):

As soon as I design how the bridge will look with that switch involved that is

There's a bunch of posts on these types of access issues/solutions, just do a search and you should find them.

Thanks Bob, I appreciate that input.  Having a liftout was a consideration, and it does solve the problem to a degree, but for my circumstances not good enough.  I don't think it would go far enough towards making certain visitors feel comfortable coming and going, and beyond all that is my #1 goal with my layouts - to share them.

The liftouts work well for some, in fact one large club where I belong to has used one for decades with success, but I don't think it's the right solution for what I'm trying to do at home.

Based on what I have gotten from this thread I think I'll be alright with a modest collection of smaller locomotives, and for that I'm stoked!  Thanks all!

For what it's worth, I took two of my Atlas trainman gondolas that have factory body mount couplers and tested them on O-54 (27"r). No problems at all. Despite the short couplers they were even able to couple on the curve (which as my friend who works for a railroad reminds me is against the rules). The test cars were pulled by an Atlas F unit with body mounted couplers.

I am using 27"r as my min radius for industrial spurs on my 2 rail layout. The 48ft gons are the largest car that will ever use these tracks so I'm good to go.

(which as my friend who works for a railroad reminds me is against the rules)

Good to know...now I can stop trying to do it and getting that feeling that my layout is inadequate

I have one car, my Seaboard Whalebelly car, that has a Kadee with very little swing to it (due to design when built).  If I'm not careful choosing which engine I run I sometimes have some rubbing of car/engine ends when negotiating an 054 curve.  Other cars are close, but if daylight can be seen between the engine and car ends It's all good

Now that is a new one on me! I don't know what railroad your friend works for, but you may want to inquire about how train crews are supposed to handle switching duties in industrial areas, where there might NOT be any straight track.

My experience with operating scale length passenger cars with Kadee fixed couplers is that anything less than O-72 is a problem and O-72 can be a problem from time to time.  

I don't have any engines with fixed pilots so I can't comment on that.  

I have found that the scale passenger cars will work OK on O-72 track with no switches.  Going through an O-72 switch (Ross and Atlas) is a problem.  Although the curve of the switch is O-72, there is almost always an S curve coming out of the switch where the diverging route turns to run parallel to the original line.  This happens in almost every yard.

In addition, there are overhang problems.  Look at the photo AG posted above.   His E units overhangs the inside of the curve by a wide margin.  Although this is an extreme case because of the sharp O-31 curve, you do get a similar overhang with scale length passenger cars and modern 89 foot freight cars on O-72.  This means that switch machines, etc., need to be low,  far from the track, or under the bench work.  You need to allow room for tunnel portals, bridges, etc., if they are close to the curve.

I suggest that you get some O-54 switches and see if the equipment you want to run will get through them without problems.  You need to plan not only for your engines but you need to plan for the cars that you intend to operate.

Finally, I haven't met a model railroader yet who doesn't have the desire to run a steam engine from time to time.  In fact, I don't know a model railroader who has been in the hobby for more than a year or so who doesn't own a steam engine.  Steam engines, especially big ones, like big curves.   You may think that you are only going to run diesels and then you see a Big Boy running at a train show and you are hooked.

Joe 

Just thinking:

I dabble in diesels occasionally, and have fixed a few pilots. I have an 072 layout.

Mixed results. The cab diesels seem to do better; I fixed the pilots on a Weaver U25B

and it was not satisfactory even on 072; went back to the swingers. If all your cars have the articulated couplers the problem will be minimized.

It's a case by case, I'd say. I have no experience with Kadees. The large drawhead of the

O-gauge couplers interferes with the swing arc, unless you mount it with more protrusion,

but that usually looks pretty dumb; opening up the "swing slot" can help, but can also leave a big gaping mouth thing.

The swinging pilot can actually be the lesser of all the evils, especially on large curves

and depending on the geometry of a given locos jawbone.

We need a very short Electrocouler, mounted close to the pilot beam.

Of course you could do Hi-rail O steam, as I principally do, and forego all these annoyances

(and have others). Again, I'm a Hi-railer (lost soul between toy trains and 3-rail scale)

and I use the big O-gauge couplers, so what do I know?

NO offense intended, but isn't that a lot of overhang on those 031 curves? 

That's good to know. I was looking at some old aerials of downtown Los Angeles and was thinking that the only thing that would work on some of the street trackage would be 27" radius (O-54). I think my GP35's and GP38-2's might be able to squeak through those with 40-foot cars in the mix.