Large Scale Central

Arch Bar Truck

Modeling
#41

Eric Schade said:

Oak is a fine wood for such a project, a little water will not hurt it and rot is not an issue unless you leave your engine out in the weather for YEARS!

I been volunteering at the WW&F Railway museum and have been helping to restore an 1891vintage two foot gauge Forney with vacuum brakes. I will be molding the diaphram for its brakes as shown in that drawing If i can!

If you are interested I have some documentation on the Eames breaks that shows pictures and diagrams of the system. PM me and give me your email address and I can send it to you.

#42

Pete Thornton said:

Devon Sinsley said:

So I might have helped my cause considerably.

I found this site showing a guy assembling an arch bar truck. Its starting to come together.

http://www.armorama.com/modules.php?op=modload&name=SquawkBox&file=index&req=viewtopic&topic_id=167320

Devon,

That’s an excellent set of illustrations. From studying Brill trucks as fitted to streetcars and the EBT M-1 gas-electric railcar, I developed some theories, yet to be confirmed.

This photo is the key:

What you see is the truck bolster sitting in a slot in the sideframe and resting on the springs. The springs rest on the sideframe, so as the truck moves up and down with the bumpy track, the bolster rides on the springs and cushions the ride of the tender.

Your truck (and thanks to Ken for reversing it so I could read it,) has a full-width crosspiece below the springs, and the bolster would be allowed a little side-to-side movement, to cater for small zig-zags in the rails. There are two pairs of ‘hangers’ preventing the truck from moving too far sideways.

You did comment that it only seems to have one spring. Erecting drawings like that often show one view on one side of the center line and a different view on the other. So you may be seeing the spring inside the hangers, and the other side shows the hanger outside the spring.

Is that the biggest image you have?

No the image I have is a PDF file that can be blown up quite large. I just didn;t know how to add it here. So I made an image of the PDF and used that. I would love to share the larger file if someone could explain how.

#43

David Maynard said:

I understand Devon, that you want to understand how the trucks work, and how the breaks on the trucks work. But since I doubt that you will actually be building working breaks on your trucks, its mostly an academic discussion.

Modeling the springs, working or not, would be necessary from a visual standpoint. Having some flexibility in the trucks, to allow them to track on less then perfect track, is helpful. Bob states that having actual springs have allowed his trucks to track better. I have found that too much flexibility in the trucks, and too much “give” in the springs can cause tracking problems on some track. Everyone’s experiences are different, and I am not saying that anyone is wrong on this point.

But I do have to question, from a time and cost standpoint, wouldn’t it be less costly to buy trucks, rather then build them? Sure scratch-built trucks would look better, but nestled under a tender, would the added effort of making them really be worth it? I am just asking. If you do build trucks, I hope you post a thread on how you do it, with a lot of pictures.

David,

Yes much of this is an academic conversation. In my modeling I try and do my best to understand the real deal. Maybe I am crazy but as I model I love to learn. I enjoy making things from scratch because then I understand the principles of the real thing better than I would if I just read about it. I am a tactile, visual learner and when I assemble something it then makes sense to me.

Why build these trucks instead of buying them, simply for the challenge of doing so. To see if I can. Understanding the workings I believe makes me a better moderler because things don’t just get attached, they get attached with purpose and reason. I am a modeler first and a runner of trains second.

I believe I will tackle this project. I appreciate everyone’s input on educating me about the wrokings of the truck. I am in the middle of building the locomotive right now but when I turn my attention to the tender I beieve I will hand make these trucks. I am even intrigued with the idea of making an estetic half leaf spring and behind it using a couple coils to see if I can make a real equalized truck that looks like it has leafs. We will see,

#44

Devon, I understand. I like to learn as I go too, and having my hands on something also helps me to understand it better then just reading about it and looking at pictures.

#45

David Maynard said:

Devon, I understand. I like to learn as I go too, and having my hands on something also helps me to understand it better then just reading about it and looking at pictures.

David,

That to me is probably the most rewarding part of this hobby to me. I will spend more money and time making something that looks worse than something I ould have purchased cheaper. But in the en I have the satisfaction of knowing I did it. This isn’t for everyone and I have no disregard for those that purchase $2000.00 accucraft models. For them the hobby is having a fine model to run on their beautiful layouts. I don’t even have a layout to run my train on… i dont even have a train that will run yet. This is a big hobby with room for all sorts. We each make it what we want. For me it is building and I am a rivet counter, that’s what makes me tick. I love knowing where all the lines go an why they go there and why they go there. So this has been a great learning experience for me on how the brake system on a truck works (although I feel a little dense because I still haven’t totally got it figured out yet).

Thanks for all your input as well as everyone elses. I hope I make an awesomely inspiring truck if not I will have learned a lesson along the way to purchasing a ready made one.

Devon

#46

Bob “IA3R-7” Cope said:

Devon,

There are those that do not believe that equalized (sprung) trucks assist in tracking. To that I say horse puckey. If rigid trucks were of no value, why would the railroads have spent so much money coming up with so many designs? Dave Maynard commented that he prefers rigid trucks, I do not. . . . . .

Bob C.

Bob,

Excuse me, but I think you missed a few important points. Equalized trucks are not the same as sprung trucks.

The proponents of rigid trucks all mention that there must be some ability for the wheels to rock, or move up and down. If one sideframe is ‘loose’ so it can rock about the central bolster a small amount, then the 4 wheels can lift or drop over track irregularities

It’s the three-legged-stool principle. Fully and comprehensively explained at http://www.clag.org.uk/41-0rev.htm. If one axle is rigid and the other can rock about its center, then the truck will stay on the track.

The prototype uses springs for the additional reason that they want to absorb the shocks of big bumps in the rails. The inertia of a fully loaded car is huge compared to our models, and without springs, the body of the car would be subject to enormous instant forces that would lead to material failure. Our models are sufficiently rigid and overbuilt (compared to the prototype) that they won’t sufer damage bumping over a rail imperfaction.

There is nothing wrong with springs. If they are the correct type, they will allow a truck wheel to move relative to the other 3 - just like an equalized truck. But they are more complicated than just making one sideframe rock, and they are difficult to set correctly. I have some trucks from a heavy brass model that I transferred to a lighter plastic car. They didn’t let any wheel move up or down! I had to remove some of the springs to make them track.

It appears that many commercial trucks have springs that hold the sideframe in place and allow some rocking movement to enable good tracking. It’s not clear they ever compress like real springs.

#47

No the image I have is a PDF file that can be blown up quite large. I just didn;t know how to add it here.

Just put it in your album (so it is stored in a 24/7 online location) and insert a link to it. Like you did for the photo on your very first post.

#48

Pete,

I have not missed any points. I may not have expressed myself as clearly as I had thought. Sprung and equalized are not entirely the same thing. It is entirely possible to put springs on a rigid truck just as it is possible to equalize an un-sprung truck. It seems to me that IN GENERAL, most of the less expensive trucks are entirely un-sprung and rigid. As I mentioned above, I modify my Bachmann and USA Trains rigid plastic trucks to allow some equalization in operation.

I also referenced changing the springs in a rather high end truck because the springs were too high a spring rate (too strong) to allow the truck to ‘flex’ in operation. I don’t believe the springs necessarily need to ‘operate’ (compress relative to empty or loaded car), but they do need to allow the truck side frames enough movement to equalize.

It is my belief that an equalized truck (not necessarily spring) will track far superior to rigid trucks. Everyone’s experiences vary and I would suppose that the combination of relatively good track work and large enough flanges would make almost any car track well. I have mostly Bachmann wheel sets in all but my AMS equipment, and have little to no issues with them, even on not so hot track.work.

Your comment regarding the necessity of springing model rolling stock is quite accurate. We are not hauling someone’s new lamp or some other extremely fragile products. However I do believe that a properly sprung truck will be naturally equalized by the ability of the truck to adapt to the contour of the rails (that is assuming the the owner has put forth the effort to put down relatively good track work).

Again, my tuppence worth, and your millage may vary.

Bob C.

#49

Pete Thornton said:

No the image I have is a PDF file that can be blown up quite large. I just didn;t know how to add it here.

Just put it in your album (so it is stored in a 24/7 online location) and insert a link to it. Like you did for the photo on your very first post.

I can’t seem to be able to store a PDF file in the albums. It only seems to want a image. It wont accept a .pdf extension

Oh wait I figured out I can do a folder so next post will have the pdf

#50

OK Pete and whoever else may be interested. As promised here is the PDF of the leaf spring Arch Bar Truck

http://largescalecentral.com/folders/file/6

#51

…and here’s a picture if you don’t want to wait for the pdf to load…

#52

Thanks for including that Joe,

Pete requested a larger file for the purpose of zooming in for greater detail. The PDF is large but allows you to zoom in and actually read what is written. I am able to zoom in over 200% (no need to go larger) and read the finer details.

For anyone that wants to have an accurate drawing to work from I recommend waiting for the PDF to load. Of course if your already up to speed on how a truck is designed then it would be redundant. However if your a fat head like me and this whole design seems to escape you this will help.

This makes me want to shelf my loco and start working on the tender trucks but I will resist the impulse.

#53

On my way to Silverton yesterday the discussion turned to “Tender Trucks”. The consensus was. Generally that tender trucks are much beefier then general purpose freight trucks. They got run all the time every day, seldom sat around for any time, as engines (and their tenders) were put to work as much as possible. Not unheard of for an engine to be out working for 16-18+ hours every day. The tenders were for the most of the time, Fully loaded, or very close to max load, and often overloaded with the addition of side boards, for more coal load, all the time, never run “Empty or light”. I would class them as “extreme duty cycle”

D&RGW 315 tender trucks (Built 1895).

BTW, the steel size in the “Arches” is dimensionally larger then in a standard truck on 315’s trucks.

#54

Those are an interesting design. I wish I had a set of those that I could climb under and see for myself how all the break linkages come together. There are a few locomotives in my surrounding area that I might have to visit. I am noticing some interesting things on these trucks. One the journal boxes are unique and they do not appear to be sprung trucks. By 1895 the certainly could have been sprung. this appears to be a rigid design where the bolster has no movement.

I wish mine had that sort of truck it would be much easier to reproduce :wink:

#55

Those are an interesting design. I wish I had a set of those that I could climb under and see for myself how all the break linkages come together. There are a few locomotives in my surrounding area that I might have to visit. I am noticing some interesting things on these trucks. One the journal boxes are unique and they do not appear to be sprung trucks. By 1895 the certainly could have been sprung. this appears to be a rigid design where the bolster has no movement.

I wish mine had that sort of truck it would be much easier to reproduce :wink:

#56

Dave,

What is the purpose of the chain?

#57

I think i am beginning to “see” this truck and its pieces. Below is a piece of the drawing that I cleaned up to show only the pieces. Do I have the function correct?

The bolster if wood as this is supposed to be according to the Baldwin build sheet must have a metal cap on the ends that rides in the frame members. I wouldn’t think they would use metal on wood. That slides up and down in the frame members which is sandwiched between the frame pieces themselves. The frame members also serve as a place to hold the brake hangers. In this picture we also see the hangersa and what I think is the arm that hooks to each brake shoe. It looks like it is part of the bolster but I believe in the drawing it is “behind” the bolster. In reality their would be two of these one on each side of the bolster for each pair of shoes. there is another piece (wood? metal?) that runs on the bottom from frame to frame on the bottom and the springs rest on that and the bolster atop the spring. does this sound reasonable.

#58

This drawing is definitely not a wood bolster truck as has been suspected. The bolster is clearly a piece of channel iron or steel. the thing that I thought was the brake arm I believe is part of the bolster. I am beginning to see through the haze I think.

#59

The 315 tender trucks are sprung, You just can’t see the spring pack behind the side frame bracing.

The Chain is a “Safety Chain”. I think it is to contain the trucks in case they were to Run Away! I can’t imagine that they would really work that way.

#60

My understanding of the chain is to keep the truck from falling off in case of some sort of catastrophic event. The tender just rides on the truck, it really isn’t attached as I understand it. There is a hole in the bolster that a pin (for the lack of a better word) that is attached t the tender goes through, and it just sits there. If there were to be an event where the tender and truck were to start to come apart it could only slide down the pin so far until the chain stops it.

Thats how I understand it. I could be wrong though.