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OK, here's another thread in my attempt to avoid re-inventing the wheel while building a locomotive...

It's time to start thinking about building tender trucks for my little lady. Purchasing them is out of the question, since nobody makes the right style, and I'm too cheap to pay for them anyway. I've already got Sierra Valley wheels, and plenty of brass and styrene, so scratchbuilding seems the logocal way to go.

I have not picked the exact style for the truck yet. I'm thinking about going with a Mason style, having seperate pedestals and leaf springs for each bearing. Or I might go with a baldwin style, having a single leaf spring per side and an equalizing lever spanning above each frame.


Now for the problem. I have concerns about a pair of rigid trucks being able to stay on the track, especially since the SV flanges are nowhere as deep as the pizza cutters on some models. Is it worth the effort to apply springs to each axle? Alternatively, is it worthwhile to hade an equalized, but not sprung, design? The Mason design would be rather tricky to hide an equalizer in, since everything is open and there was no equalizer on the prototype. Working leaf springs would be out of the question as well, but a coil spring could be hidden in there without too much trouble.


Basically, I'm wondering if anyone has any expereince and/or opinions on rigid vs. flexible trucks on a steam loco tender.
 

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Ken,
Having scratch-built in both ride-on scale and now 1:20.3, my recommendation is to at least provide equallization when using smaller flanges, such as Sierra's.
A rigid truck has a tendency to climb the rails on uneven track.
I agree that fully sprung trucks of the type you are considering are not really practical for G1, so why don't you incorporate a pivot point where each sideframe attaches to the bolster. My Roundhouse 2-6-2 tender trucks have a sheetmetal bolster, in the form of an inverted "U", with a shoulder bolt tapped into each sideframe. Each sideframe is cast to represent an equalized type, with dummy springing and floating journal boxes.

I have been enjoying watching the progress on your engine.

Larry
 

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Anytime you can introduce some amount of equalization into a truck frame, it is a good thing. If you can do it with springs, that's great, but it generally necessitates building a working truck with separate journals (if you're going to build the kind of trucks you describe) as opposed to something like an archbar or Bettendorf-style cast truck sideframe. Building the kind of truck you're thinking, I'd recommend going with the kind of construction Larry recommends, where the sideframe is rigid, but is allowed to pivot on the bolster. This not only makes construction much easier (you can build one master and cast your sideframes), but in my opinion is actually better than relying on springs for equalization. Springs are often too stiff to be of any practical use--especially on cars that don't have enough weight to actually push down on them. Once you get into heavier cars such as passenger cars, then there's enough weight to be somewhat effective, but on a tender--unless the tender is loaded with batteries, speaker, and other things--there's doubtful going to be enough weight to where springs will be remotely effective.

Later,

K
 

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Discussion Starter #4
Thanks for the comments and suggestions guys. So far, it sounds like some form of motion is a good idea. Now, as far as what that motion shoud be....

Part of my problem is that I really like this style of truck:


Unfortunately, due to the nature of it's design, the sideframes cannot be made flexible (since there's a bar connecting them front and back, and it's highly visible on the rear). As Kevin said, it would pretty much require separate working journals, but the equalizer is still a problem. Do you think it would be too obvious if I built it with a piece of piano wire hidden inside the upper frame member, and bent down to bear on the journals at each end? Would it even work?

I don't mind building the journals. I have a length of brass tube which is a near-perfect fit on the axle bearings. I also have a section of square tube which fits over that, and it an apropriate size for a journal. Thus, all that is needed are the pedestals and springs. Pedestals can be cut from brass sheet, and the springs I'll have to work on somehow... To me, though, a big part of the reason for scratchbuilding is to have what you want, and the rest is the fun of figuring out how to make it, so this seems like a good challenge.

As far as the weight, my plan is (eventually) to have one or more speakers, encosures, and batteries in the tender, and try to keep all the control circuitry in the loco.
 

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So if I get it right, you think you can make an individual sprung wheel truck, but not an equalised version of the original that was not equalised but had individual sprung wheels? Guess you answered your own question.
 

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Discussion Starter #6
Posted By Havoc on 10/01/2008 2:08 PM
So if I get it right, you think you can make an individual sprung wheel truck, but not an equalised version of the original that was not equalised but had individual sprung wheels? Guess you answered your own question.



Havoc,

The question is not whether I can, but whether it's worth bothering. That and to see if anyone else has ever done it.
 

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Now, with the photo and your additional description, here is my idea--the rectangular section in the center of the sideframe will accept a hole for an equalizing bolt. Thread it ,and all you will see is the diameter of the threaded section of the shoulder bolt, cut flush with outside and locktited. Even though prototype had rigid endpieces, attach yours with a pin or small screw in slightly oversized hole, allowing truck frame to flex and equalize.

On a much larger scale, I used this design successfully on trucks for a 1.5" scale electric locomotive's power trucks .All the springs and links are for looks only. Also, the drivers of my 4-4-0 were equalized, not sprung, and both engines track excellently.

Larry






now that I have seen the photo and
 

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Sorry about the messed up composition there. Don't know what happened.

Larry
 

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Discussion Starter #9
Wow, Larry! That's a great idea, and one I'd not even imagined. That's why I asked on here - sounds a heck of a lot easier that my ideas.
 

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due to the nature of it's design, the sideframes cannot be made flexible (since there's a bar connecting them front and back, and it's highly visible on the rear).


I'm all for equalization - it always works and doesn't require any fiddley spring settings.

The trucks on my Don Winter coach are rigid sideframes, and I added cross-bars front and back to keep the sideframes aligned, after I released the screws holding the frames to the bolster a little to the sides had some ability to rock and roll.

Your frames have the large piece connecting top and bottom bars in the center, which presumably connects to the bolster (or maybe is the bolster end!) Just make the connection to the bolster loose so that a wheel can lift very slightly - doesn't have to be much. Only one side needs to rock if the bolster/truck pivot is fairly loose.

Do you think it would be too obvious if I built it with a piece of piano wire hidden inside the upper frame member, and bent down to bear on the journals at each end? Would it even work?


Making working journal boxes with springs is tricky, unless you set it up so that the journals are always solid against the top until you meet a bump, at which point gravity or a small spring pushes one of the journals down in its frame to keep the wheel on the track.

It will work if you just set up the spring to assist the axlebox to fall when a bump or dip leaves one wheel high and dry.

It also works because these aren't driving wheels where traction is an issue. Driven wheels are best with true equalisation, so that the weight is carried on all four wheels equally at all times.
 

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Hi Ken:
You are right on concerning the need to build each truck with individually sprung wheels. I just completed building a tender for a LGB mogul and proudly set it in place for its maiden run. The bottom line is that I found it impossible to make it around the layout without a derailment. After trying a zillion combinations of loosening the various scews in the trucks , I still couldn't get the tender to stay in the rails, despite its relatively great deal of weight.

Finally, (and this won't be of any value to you given the type of truck you'll have) I located a pair of old Delton spring trucks from one of their older C16 tenders and voila, it works like a charm!

All of this is to say, you're on the right track and there is a light at the end of the tunnel (no puns).
Good luck
Jim
 
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