P48 for Cotton Belt: Roster addition SW1200

[Big Train James]

Dave,
Sorry that I've been slow to reply. I've been in a bit of a funk over here this past week and haven't summoned the energy to put fingers to keyboard until now.

I'm curious how you settled on the Cotton Belt as a prototype. It is often overshadowed by the SP. In fact, I have never truly understood why it even existed as a separate entity in the first place.

I'm also curious about the Atlas trucks. I can see in the photo of old versus new that the wheel gauge is slightly narrower. However, it also appears that the overall width of the trucks is quite a bit narrower. Is this attributed to Atlas revamping their sideframes to a narrower design, or did you move the sideframes inward on the bolsters at the same time you installed the new wheelsets? The brake shoes appear to be correctly positioned relative to the wheels.

I look forward to future posts as I'd like to see your progress. I am finding it ironic that I've come to a British model railroad forum and yet I see more US outline modeling here than on the US forums I typically frequent! Although frankly I'm seeing more modeling of any sort here than elsewhere. Anyhoo, carry on, I'm keeping my eye on you.

Apparently the righthand shift key on my keyboard has taken a . It's quite frustrating! I suppose a trip to the computer store is now in order.
Jim

 

[Yorkshire Dave]

Hi Jim

Cotton Belt, yes indeed why? It's mainly the original name St Louis SouthWestern and it's history really as it was a narrow gauge line to start with and they converted the whole main line to standard gauge over a weekend. And I have a penchant for not modelling the usual roads.

However, I've still kept my SP HO steam models (C9, M21, S8) together with a Cotton Belt Black Widow RSD5. I decided to move into US P48 for the challenge . I've already built some British O scale and I want to put the same level of detail, if not more, into a Cotton Belt GP9 as I did into my HO CN GP9 below converted from a Proto 2000 model. Yes I dabble in HO CN and BCR as well.





Regarding the Atlas trucks I found they produced a finer version of the 50T Barber-Bettendorf trucks (ref # 7064) and 70T roller bearing trucks (ref #7065). The also produce finer scale versions of the 100T roller bearing and caboose trucks. These newer trucks did not need any alteration apart from removing some material from the delrin (I think) bearings to take the Protocraft wheelsets as they have shouldered rather than pinpoint axles. As for the brake shoes, I just left them in position but you do have to check make sure they have been correctly installed at the factory i.e. brake detail facing the outside of the truck rather than the inside. They are a clip fit and can easily be taken out and turned around so the detail is on the outside.

As for your comment regarding British model railroad forums and US modelling it appears that's always the way . C'est la vie. Like you I find this forum practical and good no matter how dumb or complex the question asked.

D

 

[Jordan]

I am finding it ironic that I've come to a British model railroad forum and yet I see more US outline modeling here than on the US forums I typically frequent!

On another British Forum (RMweb - also refered to here as "Over There" ) US-resident members have commented that they seem to find it harder to get 2-rail O there than I do in the UK!!

 

[Yorkshire Dave]

Jordan - I can see why you used the Peco track pins rather than spikes. Found this picture on t'web and the spike heads are obviously rounded from being hammered into the tie.



Mickoo - no worries on the tangential picture diversions - always enjoyable . I have thought of burying most of the track to avoid tie plates .

D

 

[Big Train James]

Dave,
I've much the same plans for the Atlas gp9 but in Central Vermont rather than CN. It will look much the same as yours except that some will have steam generator details on the short hood roof, an extended fuel/water tank, and "torpedo tube" air tanks located on the roof. The CV had both steam generator equipped units and non equipped units, so both will make an appearance. The steam generator equipped units are sans dynamic brake, while the the non-SG units have the dynamic brakes. I already have in hand the Atlas spare parts including non-DB hatch and extra fuel tank parts to extend the existing one. I also have the air tank ends from Des Plaines or P&D, can't remember which. Yet another project I should get on with. You can see what my version will look like in the photos in my introduction thread.

I'm also a fan of the British Columbia Railway, and one or more of it's sd40-2's are in the idea queue as well. Two-tone green will do nicely . Red, white, and blue livery - blech ! Referencing back to Mick's US thread about having all CSX rolling stock, the BCR is actually one railway where quite a bit of the trains are populated with home road rolling stock.

Regarding the trucks, Atlas did at some point in the past several years revise their truck sideframe designs to narrow them up quite a bit. I think this change was applied across their entire line of trucks. For quite a while, the Lionel 100 ton roller bearing trucks had been the preferred choice for looks and proportions, plus they offered the additional perk of having rotating bearing caps on the ends of the axles. My problem with most trucks offered these days by most all manufacturers are the frequently wonky bolsters and what I consider to be an exorbitant price. The Protocraft trucks are pricey, but at least for the money the trucks look fantastic. I'd like to see something offered with a decent level of detail and accuracy with a reasonable price. My first step would be to do away with the live springing of the trucks which must add cost but almost never looks very convincing. Then prepare for the hue and cry from all the O scalers that seem to think it an absolute necessity. Some how HO and N scale modelers manage to successfully operate trains with rolling stock and locos lacking sprung trucks, all despite a significant reduction in mass and margin for error in track work. Ah well, all things I can address when I make trains myself since I know everything, right?

I could go on all day! I have a new keyboard - it's really quite liberating!!!

Jim

 

[Yorkshire Dave]

Jim

The way the Atlas O scale trucks are screwed together the springing does not actually work. Which means I can look at replacing them with something more convincing and the correct number of springs . I notice from photos the heavier trucks have at least 3 or 4 springs on each side.

A new keyboard - is a novel forthcoming .

D

 

[Big Train James]

Jim...A new keyboard - is a novel forthcoming .

D

Like I need any encouragement .

 

[Big Train James]

Jim

The way the Atlas O scale trucks are screwed together the springing does not actually work. Which means I can look at replacing them with something more convincing and the correct number of springs . I notice from photos the heavier trucks have at least 3 or 4 springs on each side.

A new keyboard - is a novel forthcoming .

D

I posted some photos in Mick's thread showing a 3d printed 100 ton roller bearing truck I modeled in 3d cad. Being somewhat compulsive I wanted it of course to be 100% accurate. So a lot of research was done, and data cobbled together, to arrive at the end result. One of the many things I learned about was the spring groupings for various size trucks, loadings, and eras of use. I'm most familiar with the modern trucks since that was my topic, but older and lighter trucks aren't that different.

One might be surprised to learn that a modern truck actually has upwards of 15 to 18 springs per side supporting the bolster and friction wedges, with springs nested inside each other. If you take a look at the pdf file I linked to in Mick's US thread, starting on page 33 there is information about the springs and their groupings. There are two types of springs, side and load Most modern trucks have 9 positions for spring bosses in a 3 x 3 grid. Many older, lighter capacity trucks have 7 positions, with a 2/3/2 arrangement from inside to out. The two outside springs in the center row of three are the side springs. The rest are load springs. The load springs support the bolster. The side springs support the friction wedges, which are pushed upward into angled pockets on the bottom of the bolster creating a centering thrust.

If you look at the end of a modern freight car you will see the spring grouping called out in stencils. Like this...


You will see that the designations correspond to those in the manual. The first line represents the load springs. The second line is the side springs. I don't yet know what the third line is, the fourth is obvious, the brake beam is a very common specification (typically either #18 or #24) and the draft gear is for the coupler.

The reason the springing never works on model trucks is the simple physics of it all. Any spring with properly scaled wire diameter and travel will be too strong for the mass of the car. Further compound that by accurately including enough of the springs - even say without the inner springs - and there won't be any springing to speak of. So either reduce the number of springs, or reduce their wire size and corresponding strength, or do both, and the aesthetic is compromised. On the prototype, the spring bed is essentially opaque. On most models, it is clearly open. The use of three wimpy springs for the sake of marketing that "ooooohhhh our models have sprung trucks" is almost always an epic fail. But now in the US O scale realm, toy train or otherwise, the prevailing attitude is that un-sprung trucks are "cheap" or an operational liability. Unless you are attempting to model really bad track, a la Jordan, then your track should be reliable enough to not derail all your stock. This topic gets under my skin, if it isn't obvious.

Enough for now. Let me know if you want to hear more, hah!

Jim

 

[mickoo]

Jordan - I can see why you used the Peco track pins rather than spikes. Found this picture on t'web and the spike heads are obviously rounded from being hammered into the tie.

D

Not so, my good man, they are rounded from the factory





The lettering on the head looks like a 1 then a logo in the middle that looks a cross between an 8 or B and under that MC.

Also of interest in your photo are the rail anti creep clips, you don't ever see those modeled, they are used in areas to stop the rail creeping under high loads from braking or accelerating or in our case to stop 750m of siding expanding into the traverser pit during the summer

 

[Yorkshire Dave]

Thanks for the clarification on the spike. Which piece of CSX track is missing that ? Now thinking I'll take Jordan's route and use Peco track pins for spikes.

 

[mickoo]

It was just lying there by the siding, seemed a shame to leave it there, especially as there was a pile of about a hundred or more and others just strewn around.

If they're short, I can always take it back in a few weeks

 

[Yorkshire Dave]

Jim, thanks for the truck spring info . I was also looking at the coupler and draft box in one of your pics which looks useful.

 

[mickoo]

Any use ?

 

[Jordan]

It was just lying there by the siding, seemed a shame to leave it there, especially as there was a pile of about a hundred or more and others just strewn around.

If they're short, I can always take it back in a few weeks

How the hell did you get it through Customs??!!??

The Atlas trucks can be made to have working springing, by removing the 2 screws on top of the bolster and the cross-piece they hold in place The downsides are - 1. The springs are too strong anyway (as above posts) 2. The Atlas trucks also have rotating bearing caps, so the axles run through bearings in the truck. As the truck frames twist on 'bad' track they can jam the axles. 3. As the springs are so strong, they also try to push the frames down, but at an angle, which also jams the axles. The angle is apparent if you view the truck end-on, & the bottom of the frames are trying to push in to each other, if that makes sense.
Guess how I know all that in fact I gave up trying to use sprung trucks on my bad track - it was easier to just loosen the truck mounting screws instead, although the trade-off then is possible "car wobble", a pet hate of mine!!!

 

[Big Train James]

Jim, thanks for the truck spring info . I was also looking at the coupler and draft box in one of your pics which looks useful.

Are you looking for something in particular? I've got other pictures that might better illustrate whatever it is you are pondering. Also keep in mind that while things haven't evolved too far, things may be a little different between the your modeling era of choice and the modern stock in these pictures.

Jim

 

[Big Train James]

Not so good sir, they are rounded from the factory

View attachment 46897

Hmmmm, I see the nascent form of an air filter box taking shape in the background.

 

[Dog Star]

I gave up trying to use sprung trucks on my bad track

Humm, not bad just an accurate representation of something, somewhere, sometime over there , where "over there" is a pointer to reality rather than a reference to "froth central" .

 

[mickoo]

How the hell did you get it through Customs??!!??

Well, not sure, I put one in each suitcase that went in the hold, no way that'd get past hand luggage, I saved three in all

I suppose for all they know I could of bought it as a souvenir at a railroad museum .

Bit cheeky, but worth a punt/risk.

 

[Oz7mm]

I use MicroMark spiking pliers (they are made by Xuron I believe). Excellent. I have extra pairs on order Mickoo!

John

 

[mickoo]

I use MicroMark spiking pliers (they are made by Xuron I believe). Excellent. I have extra pairs on order Mickoo!

John

Then I shall relieve you of a pair in exchange for coin of the realm if you wish.