12" working railroad

Discuss park gauge trains and large scale miniature railways having track gauges from 8" to 24" gauge and designed at scales of 2" to the foot or greater - whether modeled for personal use, or purpose built for amusement park operation or private railroading.

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Topics may include: antique park gauge train restoration, preservation, and history; building new grand scale equipment from scratch; large scale miniature railway construction, maintenance, and safe operation; fallen flags; track, gauge, and equipment standards; grand scale vendor offerings; and, compiling an on-line motive power roster.
rkcarguy
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Re: 12" working railroad

Post by rkcarguy »

Glenn Brooks wrote: Fri May 15, 2020 12:03 pm Ryan, I missed that part about the outside edge. Don’t know why the IBLS is .125. Unless they anticipate some outside edge contact with guard rails or frogs, etc. I’d probably increase the radius a bit more just for GP, and ease of handling on the fingers etc, when man handling the wheels and cars during operation. Prototype wheels are pretty heavily radiused as I recall...
I did some internet image searching and found some interesting results, the more square flange corners are fairly common in light rail metro applications while freight wheels have a very rounded outside edge. I wonder with the weight that freight trains move if they are concerned with the more square corner striking something and allowing a crack to start?
With the clearance I'm running between the rails and guardrails (.080" on straights and I stretch it to .125" on curves, and .400" guardrail/frog spacing) a large outside radius serves no purpose. It's easy enough to sharpen another tool though to round those corners off with a bigger radius, or just give it some more time with the file. I will need yet another QCTH if I go with another lathe bit though.
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Re: 12" working railroad

Post by Glenn Brooks »

The Square edges are certainly stress risers, multiplied by millions of ton miles of high speed service for each fright car wheel. Also I think the freight car wheels take enormous amount of abuse in freight yards, constantly striking switches, frogs, and guard rails. Seems like there may be consistent contact with the outside edge in these cases. Flip side, a square edge would play havoc with what ever it strikes... so maybe radii is a defensive measure as well.
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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NP317
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Re: 12" working railroad

Post by NP317 »

Rounded flanges are less likely to climb rails, frogs, and guards.
Sharp edges can dig in and climb. And derail.
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Re: 12" working railroad

Post by rkcarguy »

Another wheel set done tonight, and I decided to try fitting them to the truck. All was going well until I went to tighten the pillow block bolts and they are a little too long, just snug against the face of each wheel ugh. So I need some bolts about 1/8 shorter.
As for the flange radius, I found my lathe file and it cut much better so I was able to round a nice .080” radius pretty quickly.
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy »

Just an FYI, I know BDD, Harold, Glenn and I were discussing hardening of steel from the heat of laser or plasma cutting. On my little south bend 9" lathe it has enough umph now with the 1HP motor to cut the angle on the side of the flange ( side that you can see in my last picture) 1/8" at a time so it's just a couple passes. I just bury the side of the 8* tool into the flange instead of rotating the compound. The backside is where the heat built up during laser cutting and its noticeably harder, I have to take several small passes here and after each pair of wheels the carbide is pretty tired and it requires a trip to the grinder before the next wheelset.
I've got it down to about an hour per wheelset, one more to go for the riding car.
Last edited by rkcarguy on Wed May 20, 2020 1:23 pm, edited 1 time in total.
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Re: 12" working railroad

Post by 0351 »

Looking good!
Lol, something looks vaguely familiar about your trucks. Been playing around with my booster bar setup. Looks like the Chevy valve spring will work good for me.
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Re: 12" working railroad

Post by 0351 »

Ryan, are you still going with your bolster center pin design?
I’m seriously considering going with the Grand Scales center plate. It’s slightly wider than my 3”
Bolster bar, if I add a 1/2” plate base to bolt it to I believe it’ll work out good.
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy »

Hey Curtiss,

Good to see you making some progress.
The riding car trucks above were my first revision, yours were scaled up and modified from those to closer match the NG truck sides.
I have yet another version I'm using on my next builds that utilize 3/4" pillow blocks instead of 1" for a better look, the load limit on the 3/4" bearings is close to the 1" and still gives me 3 tons of capacity, way over my needs and capacities of the frames and other parts.
The bolster setup I run is Bigdumbdinosaur's design, it uses a spherical bearing (either self-aligning pillow block or separate spherical bearing), for the bolster pin pivot and separate "thrust bearings" that ride on the underside of the frame to support the load. This allows the truck to swivel up and down to equally distribute weight even with the train navigating a ramp onto or off of a trailer with a notable change in track elevation, independent of the compression of the springs, but doesn't allow any tip side to side. Its rather cheap. I'm using 3/4" 2 bolt pillow blocks ($8 each) at the bolster pins and 1/2 x 1-1/8 ball bearings as the "thrust bearings" and they were only $15 for tube of 10 on amazon. The riding car uses spherical bearings at the bolster pins but the function is the same, zoom in on that 3rd picture and you can see the "thrust bearings" sticking up on their pedestals.
I've already incorporated this into my locomotive and rolling stock designs and have parts already made for my 2 bulkhead flat cars.
The "ballast gondola" is going to be a beast, so I'll be doing a custom set of super duty parts for that later.
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Steggy
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Re: 12" working railroad

Post by Steggy »

rkcarguy wrote: Wed May 20, 2020 1:21 pmThe bolster setup I run is Bigdumbdinosaur's design...I'm using 3/4" 2 bolt pillow blocks ($8 each) at the bolster pins...
Not too much overkill, eh? :D
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rkcarguy
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Re: 12" working railroad

Post by rkcarguy »

BigDumbDinosaur wrote: Wed May 20, 2020 4:32 pm
rkcarguy wrote: Wed May 20, 2020 1:21 pmThe bolster setup I run is Bigdumbdinosaur's design...I'm using 3/4" 2 bolt pillow blocks ($8 each) at the bolster pins...
Not too much overkill, eh? :D
Error on the side of caution and things will hold up when the unforeseen need to max them out arises. That's my motto :)

Actually I have to take that back though. The locomotive has the 3/4 pillow blocks on bolsters and I doubled up the bearings so it would be good for about 2000#'s. The riding car and bulkhead flats are using bronze-ball, steel-housed spherical bushings. and I'm going to use bronze bearings to take the load on the bulkhead flats. I'm also going to go back to the 3/4" 2 bolt pillow blocks for the ballast gondola.
The nice thing about this design is it doesn't require the bolster surface to be perfectly flat or the pin perfectly straight, as it acts only as a pivot point. The bearings that ride on the frame keep things straight and level, and also distribute the load much closer to the wheels instead of at the center of the bolster.
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Steggy
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Re: 12" working railroad

Post by Steggy »

rkcarguy wrote: Wed May 20, 2020 5:02 pmThe nice thing about this design is it doesn't require the bolster surface to be perfectly flat or the pin perfectly straight, as it acts only as a pivot point. The bearings that ride on the frame keep things straight and level, and also distribute the load much closer to the wheels instead of at the center of the bolster.
That was the intent when I conjured that arrangement. It has worked out very well on my F-unit and the riding car.

Something else that I periodically think about is devising a means to dampen truck motion in roll. On full-sized locos, that is the function of the shock absorber-like devices (roll dampers) that are attached to the bearing boxes and truck frames. As our small stuff typically has a higher center of gravity relative to size than the full-sized stuff, there is more of a tendency for rocking on uneven track. At the right speed over the uneven sections, it is conceivable the natural rocking frequency could be sufficiently excited to cause the wheels on one of the trucks to be lifted clear of the rail. Roll damping would oppose that effect, but without interfering with the trucks' ability to conform to uneven rail.

As there are no scale-sized dampers of which I am aware that would be able to do the job, I had an alternate idea of incorporating an anti-roll bar into the truck. The bar would be supported on the truck bolster by some bearings (sleeve, most likely) and the bar's ends would be linked to the axles or bearing boxes in some fashion. Purely vertical motion would merely rotate the bar. However, rocking motion would try to twist the bar, which would resist the rocking motion.

It's only theory...
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Re: 12" working railroad

Post by rkcarguy »

0351 wrote: Wed May 20, 2020 12:21 pm Looking good!
Lol, something looks vaguely familiar about your trucks. Been playing around with my booster bar setup. Looks like the Chevy valve spring will work good for me.
All you'd have to do is mount a 2 bolt pillow block to the center of that bolster, and add two stanchions which come up from the bolster with bearings on them at the proper height to push on the frame. I disassemble the pillow block and flap wheel the bore of the self aligning portion a little so they move easier, but if you have more weight it may not be needed.
One word of caution, make sure your stanchions clear your brake shoe linkage before you weld or bolt them on.
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