7j43kOvermod, I trust you are getting my point.
I didn't go into that detail as I was only concerned with potential momentary contact of a (potentially wobbly) car with a standing adjacent train with its now-fixed overhangs. I think by the time we get to Unstoppable-grade levels of tilt, we're no longer in the realm of advice to the OP on reasonable track spacing for his purposes. Even modeling of negative cant deficiency in passenger models (which Hornby did, and I presume Rapido did with their APT model) is on the esoteric side for typical modeling concerns -- although not for Amtrak on the NEC north of New Haven...
The other point in question is the wobble. Yes, good models shouldn't wobble, but a good three-point side-bearing arrangement implies that the 'stiff' truck can prevent any roll of the carbody including when the 'far end' leads into what may be sharp curves and its angular momentum change is accommodated via the center pin of the 'tiltable' truck. Long practical evidence with good model railroading practice certainly indicates this doesn't rise to the level of a chronic derailment cause, but in some cases, especially with sprung or 'articulating' sideframes, it might prove to increase the effective upper-outer 'critical contact radius' enough to matter if the situation were already critical.
All this palaver is fun but I don't think it's getting the OP much closer to what he was asking to know...
Overmod All this palaver is fun but I don't think it's getting the OP much closer to what he was asking to know...
Here's a bit more on the subject:
On a 38.5 inch radius curve, the tightest in the yard, a 65' long freight car (the potentially most troublesome) will project an approximate additional 1/8" inwards. It will not project outwards that much. Since there is 2" between track centers, and a freight car is about 1.5" wide, there is 1/2" available for clearance WITHOUT accounting for increased curve overhang.
1/8" is dramatically less than 1/2", so I say clearance in the curves in the yard for the type of cars and locomotives that will be in it is more than adequate.
IF projection outward in the curve were to also be 1/8" (which it will not), and two of these cars were passing, there would still be 1/4" clearance.
Note that no road engines nor passenger cars will be in this yard.
Now, the arrival/departure tracks might be different. I see a 37" and a 39". If an articulated is planned on being operated there, overhang outwards for the boiler front should be considered. And perhaps outward overhang on each end of a 4-8-4. Articulateds could be limited to the outer track, and likely things would be fine there.
I also note that two of the three A/D tracks don't have much straight near the switches, perhaps generating difficulties adding/removing engines and cabooses.
It would be wise if the OP were to do some overhang measurements and calculations for the "biggest" motive power and passenger cars on specified radii before locking things in.
I took a few minutes and found that the outward swing of a Big Boy's front would be a half inch on that 37" radius A/D track, so running such an engine on that track would not work out if there were cars on the next track. In fact, if articulateds are contemplated on the layout, some double-checking all over might be in order. For the A/D tracks, it might make it a fun challenge to limit articulateds to the outer of the three tracks.
Except for 89' flats, passenger cars are the big challenge on INWARD overhang. On a 37" curve, they will come inwards about a quarter inch. And less outwards.
Looks like the biggie on curves will be articulateds.
Ed
OvermodI didn't go into that detail as I was only concerned with potential momentary contact
This potential contact needs to be avoided because it will happen at the most fragile parts of detailed train cars. The corners and the center.
-Kevin
Living the dream.
7j43k SeeYou190 My 2-8-8-4 will need to be restricted to the outermost of my hidden return tracks. The cab overhang is so excessive on the outside of the curve that this is necessary. -Kevin Mmmm. Me like! Good! (Sorry about letting my inner kid appear--it happens.) Ed
SeeYou190 My 2-8-8-4 will need to be restricted to the outermost of my hidden return tracks. The cab overhang is so excessive on the outside of the curve that this is necessary. -Kevin
My 2-8-8-4 will need to be restricted to the outermost of my hidden return tracks. The cab overhang is so excessive on the outside of the curve that this is necessary.
Mmmm. Me like! Good!
(Sorry about letting my inner kid appear--it happens.)
I am amazed by the Bachmann 2-8-8-4. It runs like a fine watch, looks good, and will negotiate a 22 inch radius curve.
SeeYou190This potential contact needs to be avoided because it will happen at the most fragile parts of detailed train cars. The corners and the center.
I think Ed (and indirectly Mike) are correct about the relative unimportance of many factors on curved yard track spacing, including that nonprototypical articulated-locomotive outward overhang will likely be 'controlling'.
I'd be interested to know if the 'test' 86' boxcar has more inward interference than typical passenger cars -- likewise if 89' flats are in the same general category.
At least some of the changes to the NMRA 'gage' will be AAR plate changes over the years, with plate H now being common. Do any modern Plate H models have more serious momentary-contact inside overhang than the old 86' boxes?
Here's Gritton's useful 'unified' plate reference again, through plate H:
https://gritton.org/greg/rail/docs/clearance/AAR_plates_with_UIC.gif
Note the 'kinematic' adjustments, but more importantly the AAR recommended clearance for Plate H.
SeeYou190 7j43k SeeYou190 My 2-8-8-4 will need to be restricted to the outermost of my hidden return tracks. The cab overhang is so excessive on the outside of the curve that this is necessary. -Kevin Mmmm. Me like! Good! (Sorry about letting my inner kid appear--it happens.) Ed I am amazed by the Bachmann 2-8-8-4. It runs like a fine watch, looks good, and will negotiate a 22 inch radius curve. -Kevin
But it has some serious overhang at that radius........
It just barely stays in the 2" track center window at 36" radius.
Sheldon
ATLANTIC CENTRALBut it has some serious overhang at that radius........ It just barely stays in the 2" track center window at 36" radius.
Yep, that is why the operational restriction to the outer hidden loop only.
As far as I know, this is the only piece of equipment I have with an operational consideration like this.
When I said that a Big Boy would overhang outwards on a 37" curve by 1/2" (using up ALL possible clearance at 2" centers), that was based on a model locomotive with a non-swiveling rear engine.
7j43kWhen I said that a Big Boy would overhang outwards on a 37" curve by 1/2" (using up ALL possible clearance at 2" centers), that was based on a model locomotive with a non-swiveling rear engine.
Ed, I have compared two articulated locomotives, a Bowser 4-6-6-4, and a Bachmann 2-8-8-2. They have different designs. The Bowser has a rigid rear engine (prototypical), and the Bachmann has both engines able to rotate (non-prototypical).
I know a lot of this is apples-to-oranges, but this is what I have noted.
In prototype design, the boiler front seems to overhang a lot more on tight radius curves. With both engines rotating, boiler overhang is less, but cab overhang is increased.
Overall, both seemed to require a relatively equal side clearance.
Both of these locomotives would negotiate a 22 inch radius curve, and both looked completely ridiculous doing it.
I'll note that my overhang dimension for the Big Boy was based on drawings of the engine. With the normal slop in HO models, I wouldn't be shocked to find more. Or even less.
I'll mention that 4-12-2's don't have this problem!
SeeYou190 7j43k When I said that a Big Boy would overhang outwards on a 37" curve by 1/2" (using up ALL possible clearance at 2" centers), that was based on a model locomotive with a non-swiveling rear engine. Ed, I have compared two articulated locomotives, a Bowser 4-6-6-4, and a Bachmann 2-8-8-2. They have different designs. The Bowser has a rigid rear engine (prototypical), and the Bachmann has both engines able to rotate (non-prototypical). I know a lot of this is apples-to-oranges, but this is what I have noted. In prototype design, the boiler front seems to overhang a lot more on tight radius curves. With both engines rotating, boiler overhang is less, but cab overhang is increased. Overall, both seemed to require a relatively equal side clearance. Both of these locomotives would negotiate a 22 inch radius curve, and both looked completely ridiculous doing it. -Kevin
7j43k When I said that a Big Boy would overhang outwards on a 37" curve by 1/2" (using up ALL possible clearance at 2" centers), that was based on a model locomotive with a non-swiveling rear engine.
I completely agree with that assessment and will add that as the radius increases, the double swivel designs have less front overhang, while the fact that the rear engine swivels becomes much less noticable.
So while it may not be prototypical, the double swivel design is a great appearance compromise even for those with large curves. It makes your large curves look larger.
All of my articulated locos are modern plastic/die cast double swivel designs and look fine on 36" radius and above.
The EM-1 is the biggest overhang offender on my roster.
The others:
Spectrum 2-6-6-2's
Proto 2-8-8-2's (now 2-8-8-0's)
BLI N&W A 2-6-6-4's
Rivarossi C&O H8 2-6-6-6 (#2 overhang offender)
I'll second Sheldon's Rivarossi H-8. My 2005/6 version came with two cabs, believe it or not. The one installed had the shorter cab roof overhang of the two, the extension reaching back to the tender. They're fragile, and I broke the optional cab's extension. Had I installed it, it's side clearance intrusion into track spacing would have been quite serious in my estimation. The nose of this beast is bad enough, and the engineer's injector overflow catches on stuff near the tracks, things like shrubs or lineside details. Beware!
While I have your attention, look up! What trips me with overhead clearances are pantographs, the chimneys on the odd caboose, crane booms....don't just look to side clearances. That NMRA gauge is just a guide.
selector That NMRA gauge is just a guide.
That NMRA gauge is just a guide.
Alton Junction
Okay, quick question. Designing a switching layout. Two places will have parallel tracks on curves. Thinking of 22 and 24-inch radius curves. HO scale, 4 axle locomotives and max car size is 60 ft. Good?
On tangent track, you'll have half an inch between two cars with two inch track centers.
On a 24" radius curve, a 60' car will overhang INWARDS by a quarter inch. Overhanging of cars OUTWARD will be less, maybe an eighth of an inch. Probably less.
So. You should be able to pull it off. With at least an eighth of an inch to spare.
I say it will work.
But.
If I'm wrong, who loses here?
I recommend you build a couple of test curves to confirm things.
7j43k I recommend you build a couple of test curves to confirm things.
Rich
Okay, will mock it up when have some benchwork up... Thanks.
Arguments over mathmatics? That's an interesting engineering/physics discussion, Einstein. And accounting for the forces created by models that have essentially no mass would be a challenging calculation.
I would assume that the input variables would determine proper spacing, such as intended equipment length and the need for finger space should you want to handle the cars.
Kinda like the lack of absolute sandards real railroads would have, since input variables like available flat real estate and clearence for vehicle/people movements might be desirable and vary from location to location.
In a nutshell, although situations vary, but no matter what the situation, clearence is clearence. Clarence.
Were you guys ever part of that "toast" thread that was on the forum many years ago, or that thread about the theoretical problems different screws might have when twisting into benchwork? I liked those too.
- Douglas
Railroads have no absolute standards?
4' - 8 1/2"
And there are standards for tolerance on that dimension.
There are Plate standards. And all Plates have a maximum width of 10' - 8".
There are clearance standards, by States, in this case. Washington and Oregon come to mind. Those standards are for ALL railroads in each state. They are remarkably similar.
It's pretty hard to set up a rail system that can move a railcar to anywhere track goes in North America without some kind of standards.
Goodness. I was refering to the context of the topic, the possibility that yards may have closer track spacing depending upon the types of equipment occupy the yard or the need for a vehicle to be able to get from one end to the other, among various other possible inputs to an equation.
I wasn't referring to the absense of standards about anything anywhere.
You guys crack me up.
Douglas,
It would have been good if you had used those very words the first time. They are well written and clear. Unfortunately, your earlier attempt was not. What with "mathmatics", "Einstein", "toast", it was a bit meandering.
You make a good point by bringing in prototype practice, and that it might vary. I think this was discussed recently in another topic. I think the main concern here is on the layout level, however: Crashing trains and room for fingers and such.
I am glad we provide levity for you. I am sure you provide levity for some of us, and I hope that pleases you, also.
7j43k Douglas, It would have been good if you had used those very words the first time. They are well written and clear. Unfortunately, your earlier attempt was not. What with "mathmatics", "Einstein", "toast", it was a bit meandering.
Plus, he spelled clearance wrong, twice.
richhotrain 7j43k Douglas, It would have been good if you had used those very words the first time. They are well written and clear. Unfortunately, your earlier attempt was not. What with "mathmatics", "Einstein", "toast", it was a bit meandering. I was surprised by the sarcastic nature of that post by Douglas. It was out of character for him. Plus, he spelled clearance wrong, twice. Rich
I was surprised by the sarcastic nature of that post by Douglas. It was out of character for him.
I guess I thought with the exception of the only serious posts that addressed the topic correctly.....you and Kevin basically saying that "it depends" , that the bulk of the thread was unserious, semi scarcastic banter.
I thought that theoretical discussions about preplanning the precision needed to lay track similar to engineers building a 747 was actually a big joke...like the Toast thread and the five page discussion on torquing a screw into plywood years ago.
My apologies for misunderstanding if folks were being serious.
BTW, an NMRA gauge? I've been in the hobby 40 years and built three layouts (yes, successfully) and I never could figure out what I would use it for.
Still having fun, with no derailments, mysteriously uncoupling cars, or shorts occuring on Peco turnouts.
Not sure where Kevin fits in here. I was agreeing with Ed that the OP should test the track for clearance, and I made that same argument earlier in the thread, the very first reply in fact. I was being totally serious. I am a big believer in mathematics, but I also respect empirical evidence. When you are dealing with clearance on curves, test it.
Anyhow, all's well that ends well.
P.S. It looks like you edited your last reply after I posted mine. The reference to engineers building a 747 totally baffles me. Are you confusing this thread with some other thread?
richhotrain Not sure where Kevin fits in here. I was agreeing with Ed that the OP should test the track for clearance, and I made that same argument earlier in the thread, the very first reply in fact. I was being totally serious. I am a big believer in mathematics, but I also respect empirical evidence. When you are dealing with clearance on curves, test it. Anyhow, all's well that ends well. Rich
Kevin offered his advice based on experience. I thought that the advice that was based upon arguing the possible mathmatical solutions in the planning stages were less than sincere about answering the OPs question and more about something else...what I'm not sure.
If you take your advice about testing various combinations, and go through several iterations, you could lay two pieces of track, have it work for 40 years, and never ever know what the exact spacing between centers was.
The only reason you would have to measure it...at all in 40 years... is if you were going to lay another track in exactly the same yard where the exact same equipment would run...where no vehicles would be passing...where no maintenance shed would be located. Change one variable, and the spacing required changes too. And, you wouldn't even need to measure it if you simply eyeballed it and had enough space to work with to account for being 3/32nds off on a few tracks.
I guess I get frustrated when answers are given that imply its "only the engeering way or the hiway" when it comes to layout building.
Well, here is my reply to the OP, verbatim, and it was the first reply to this thread.
It was a serious reply based upon my own experience.
After I posted that reply to the OP, my subsequent replies were in support of Crandell's and Ed's similar responses - - - test the trackwork to see if it creates clearance problems or not.
richhotrain I don't have an absolute answer for you, but I can make some suggestions. A minimum radius of 36" is great, especially on mainlines, but not really necessary for yards. What is more important on curves is the spacing between tracks, and 2" on center on curves is tight even though you are limiting your rolling stock to 40' and 50' freight cars. Spacing of 2 1/2" on center on curves is far better, at least in my experience. Years ago, I got some good advice from my LHS guys about spacing of tracks on curves. They recommended that I buy a pair of 85' boxcars and test them on actual track to be sure. I wouldn't blindly rely on the advice of others unless they can say with certainty that 2" on center spacing for 36" radius tracks will work based upon their actual experience. If this were my layout, I would use 2 1/2" spacing on curves and, since it is the yard, I would step down the radius on curved tracks to something like 32" radius. In fact, that is exactly what I did on my old layout where I installed a yard on a curve on my layout. Hope this helps. Rich
I don't have an absolute answer for you, but I can make some suggestions.
A minimum radius of 36" is great, especially on mainlines, but not really necessary for yards. What is more important on curves is the spacing between tracks, and 2" on center on curves is tight even though you are limiting your rolling stock to 40' and 50' freight cars. Spacing of 2 1/2" on center on curves is far better, at least in my experience.
Years ago, I got some good advice from my LHS guys about spacing of tracks on curves. They recommended that I buy a pair of 85' boxcars and test them on actual track to be sure. I wouldn't blindly rely on the advice of others unless they can say with certainty that 2" on center spacing for 36" radius tracks will work based upon their actual experience.
If this were my layout, I would use 2 1/2" spacing on curves and, since it is the yard, I would step down the radius on curved tracks to something like 32" radius. In fact, that is exactly what I did on my old layout where I installed a yard on a curve on my layout.
Hope this helps.
richhotrain Well, here is my reply to the OP, verbatim, and it was the first reply to this thread. It was a serious reply based upon my own experience. After I posted that reply to the OP, my subsequent replies were in support of Crandell's and Ed's similar responses - - - test the trackwork to see if it creates clearance problems or not. Rich richhotrain I don't have an absolute answer for you, but I can make some suggestions. A minimum radius of 36" is great, especially on mainlines, but not really necessary for yards. What is more important on curves is the spacing between tracks, and 2" on center on curves is tight even though you are limiting your rolling stock to 40' and 50' freight cars. Spacing of 2 1/2" on center on curves is far better, at least in my experience. Years ago, I got some good advice from my LHS guys about spacing of tracks on curves. They recommended that I buy a pair of 85' boxcars and test them on actual track to be sure. I wouldn't blindly rely on the advice of others unless they can say with certainty that 2" on center spacing for 36" radius tracks will work based upon their actual experience. If this were my layout, I would use 2 1/2" spacing on curves and, since it is the yard, I would step down the radius on curved tracks to something like 32" radius. In fact, that is exactly what I did on my old layout where I installed a yard on a curve on my layout. Hope this helps. Rich
I know. That's what I was saying. I thought your post was a serious answer. Yes, there were a few more scattered in but a lot of it reads like that five page long thread about what SHOULD happen when you torque different screws into different grades of plywood based upon the different properties designed into the steel and plywood.
That was a thread that made fun of itself for being overserious about a simple question. At least that's the way I read it.
Maybe I'm different and have simply gotten lucky. Common sense has always worked for me. But common sense tells me that I should not use common sense to build an airplane.
My mathematical responses are completely serious.
Mathematics can be quite useful in our field. For example, if you have a room 12 feet wide and you want layout 4 feet wide on each side, I can tell you the aisle width without having to lay out and measure a real room. Or even measuring off of a scale drawing.
My calculations were a slight step above that operation.
I suggested building a test setup because of the "trust but verify" concept. Plus, with our models, there can be an amazing amount of slop in mechanical dimensions, especially in trackwork.
Also, the layout builder might find that, although the clearances are what I predicted; in real life, those clearances are still too small for his tastes (sorta how they must do airplane seating).
7j43kI suggested building a test setup
I always suggest building a test piece first. This is always time well spent.
Anybody care to guess what this track spacing would scale down to in terms of inches on center? Keeping in mind that its likely designed for a fairly uniform type of car. (Hoping the watermark printing satisfies copyright requirements).
Or this?
Or the yard that has access down the middle?
Hard to tell....
Do all the tracks in a yard even have the same center spacing?