Ideas needed for spring equalized truck

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apm
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Ideas needed for spring equalized truck

Post by apm » Sat May 10, 2014 9:10 pm

I took a little detour from the prints on my RMI Forney and am trying to figure out how best to do the spring rigging on the trailing truck. Here's where things are at right now;
Image

About the only prototype photo I can find online was the following;
Image

I am trying to figure my way through how best to set this one up, does anyone have any photos from builds of similar trucks?

In particular how do the springs attach to the bottom of the strap hangers in the prototype photo?

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makinsmoke
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Re: Ideas needed for spring equalized truck

Post by makinsmoke » Sat May 10, 2014 10:20 pm

It looks to me like two u shaped hangers are attached one at each
end of the springs and are hung from the two bolts that have
castellated nuts on the outside of the equalizers. The spring ends
sit in the bottom of the loops. Everything hangs between the equalizers.
I would be more interested in how the bolster is attached.

GS14403
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Re: Ideas needed for spring equalized truck

Post by GS14403 » Sat May 10, 2014 10:50 pm

Your truck looks like it is constructed similar to my lead truck. Here is a picture of the truck apart when I was painting it. The spring ends are secured in rectangular shaped straps and the center of the spring sits in the side frame. There is a half round on the spring and a corresponding shaped piece on the sideframe. The photo wasn't taken to illustrate the parts per se but hopefully it is clear enough so you can see how the parts are in relationship with each other.One thing that becomes painfully obvious is scale size springs are too stiff. For my lead truck I ended up putting in a coil spring in the bolster mount to the frame to give some vertical movement.

There is some more information about the coil spring in my GS-1 thread in the build section.

Donald
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Fender
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Re: Ideas needed for spring equalized truck

Post by Fender » Sun May 11, 2014 5:30 am

If you haven't already, suggest you look at the thread on "Converting a Baldwin 2-4-2 LYN...." in the Build forum, as there is a lot of information on forney trucks there.
Dan Watson

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Bruce_Mowbray
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Re: Ideas needed for spring equalized truck

Post by Bruce_Mowbray » Sun May 11, 2014 9:12 am

When my friend Ed built his kitbashed Forney, he used Mercer's Reading A5a tender trucks as a base. A simple swing link setup was built with the links hanging from the cross bars down to the lower portion of the bolster casting. Nothing fancy and close to prototype. His locomotive tracks beautifully even on rough track.
Bruce Mowbray
Springville & Southern RR
TMB Manufacturing & Locomotive Works

tomc
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Re: Ideas needed for spring equalized truck

Post by tomc » Sun May 11, 2014 9:25 am

Here is a picture of our driver spring, it is almost the same as the tender. The main leaf has the holder on it that hooks into the strap. What we found, if the end isn't flat, it will slip out of the holder strap.

Tom C.
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jabsteam
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Re: Ideas needed for spring equalized truck

Post by jabsteam » Sun May 11, 2014 1:47 pm

Looks like your truck is already set up for the leaf spring equalizer setup like in the prototype photo.

You have the bolster guides already at the top of your truck frame. There looks to be 2 ways to set up your bolster;

One way would be bolster inside the frame guides, hung from bolster swing links mount outside the bolster guides.
This would get you some side swing/play necessary in the rear truck of a Forney. Probably not enough to negotiate
model track curves, though.

Another way would be to mount the bolster between the frame guides supported by coil springs behind the truck frame
down to a spring plank mounted from side frame to side frame. This would get you additional suspension for better tracking,
especially if this is to be a ride-in Forney. However, it will not address the problem of additional swing needed on a Forney
rear truck to negotiate model curves.

How does RMI allow for rear truck swing on their Forney? (not swivel)

Hudson Honey
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Re: Ideas needed for spring equalized truck

Post by Hudson Honey » Sun May 11, 2014 2:47 pm

On my hudson build thtead you can see how the lead truck springs are done.

Would be in the very early pages of the build log


Pamela

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Bruce_Mowbray
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Re: Ideas needed for spring equalized truck

Post by Bruce_Mowbray » Mon May 12, 2014 9:20 am

My friends side to side play is about 5/16" each way, 5/8" total. Keep in mind that the trailing truck aids a Forney in navigating curves by preventing the "waddle" effect especially with such a long back end. The track we tested it on was FAR from perfect. Large dips and curves with less than a 30 foot radius abound. I asked him for some pics of his design. Will post when I get them.
Bruce Mowbray
Springville & Southern RR
TMB Manufacturing & Locomotive Works

chooch
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Re: Ideas needed for spring equalized truck

Post by chooch » Mon May 12, 2014 1:30 pm

Not sure if this diesel locomotive truck would work for you but-they look similar with Coil springs.
Good photos and for sale BTW from https://www.facebook.com/WBRCS
West Bend Railcar Shops--David Gehrke.
Also the truck photo is on Discoverlivesteam.com --listed on for sale page, rolling stock, track etc.

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apm
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Re: Ideas needed for spring equalized truck

Post by apm » Mon May 12, 2014 4:11 pm

Thanks everyone for the replies.

Tomc, I was looking at the picture you posted with the clip on the end, that's the clip that I am trying to figure out how best to make at this point. How are you attaching it? I plan on using hard spring steel leaves for my leaf springs. I would be inclined to braze on the shoe or maybe even weld it, however i figure that there should be a lot of cyclic stresses there that would try to snap open any weld/braze joint if not done correctly there as the whole motion of those leaf springs kind of reminds me of just twisting back and forth on a paper clip.

Fender, I had not seen that build log, thank you very much for pointing my attention to it, that is more or less what I am trying to do here.

When it comes to the bolster and how to attach the truck to the locomotive, I have been going back and forth with how best to do this. A while back Jack Bodenmann was kind enough to send me his sketches on how he set up his trucks on the #9. I made some modifications to the design however here's more or less what I currently had planned;
Image

Hard to see in the photo is that the block between the 2 springs has a welded pivot that goes to a plate below that is welded onto the top of the trucks. That plate either will get heavily greased or contain a thrust bearing there. I still haven't quite decided on all of it yet but those were along the lines I was thinking. I really would like to with the prototype way as much as possible, but it sounds like so many people have had great difficulty getting Forneys to navigate such sharp turns that it sounds like I will avoid doing it.

I would be really interested however in seeing what others here have done.

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Loco112
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Re: Ideas needed for spring equalized truck

Post by Loco112 » Mon May 12, 2014 9:08 pm

APM, what is the prototype that your prototype tender truck photo came from?
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