Sprung drivers?
#1
Question: I'm building a mechanism for an HOn3 2-8-2. I notice many imported brass steamers have sprung drivers. My mostly MDC kits are simply axles riding in slots of a die-cast frame with no bearings or springs. They run fine, but I wonder if sprung drivers would improve electrical pickup and traction. Is it worth it to make the drivers of my new mechanism sprung? Or is it just added complexity for very little gain?
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Kevin
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#2
I've never done it. Are the side rods on the model jointed or a single piece? A single piece rod might remove any benefit from springing.
David
Moderato ma non troppo
Perth & Exeter Railway Company
Esquesing & Chinguacousy Radial Railway
In model railroading, there are between six and two hundred ways of performing a given task.
Most modellers can get two of them to work.
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#3
If your track-work is perfect, unsprung locos will perform adequately, but a few bumps may introduce loss of electrical pick-up and tractive effort.

I would build the beast per instructions, then if it's not up to your standards, make some mods.

This is probably more than you want to know about the subject;

<!-- m --><a class="postlink" href="http://www.clag.org.uk/41-0rev.html">http://www.clag.org.uk/41-0rev.html</a><!-- m --> (The principles of model locomotive suspension)

These guys have taken this to a whole other level.

Read up and choose how far you want to go.

Dan M.
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#4
Kevin,
i understand your question. As far as my experiences are, the electrical pick up will improve definitely better when all wheels have permanently contact to the railhead.
Thanks to Dan M. for the link. This is a very advanced group for running gears and i will tell you how far i went.

European models, especially of German prototype are beautiful looking pieces but sometimes very poor runners because of nasty running gears. As deeeep flanges are common here, which prevent derailing on uneven track, there is no necessity for the manufacturers to develop equalized running gears or anything else in this direction. In fact the rigid running gear of a todays loco model is just the same as it was in the aera of clockwork powered miniature trains. Most Modellbahners are satisfied running their trains in a speeding toy like matter on old and older tracks and even still older worn out tracks.
But not all of them.

This was one of those cases of a beautiful looking 0-6-0 Rangierlok / switcher / shunter but a lousy runner. The motor is good, the gear and gear ratio is good, but main problem was the poor electrical pick up. Speeding yes, but crawling?
To show what i am meaning, a couple of photos:
[Image: dsc089426lkw9.jpg]
There i have made a huge dent into the rail for demonstration purposes. The left side wheels of the first an second axle have airtime. Your track on the layout will be far better than this, but even a gap of 0,02mm is a insulator for electric current.
[Image: dsc08943tsjs9.jpg]

[Image: dsc08944jrkhb.jpg]
Third axle over the dent, has contact to the rail. But now the the right side wheels of axle 1 and 2 have the airtime ... :wait:
And made your prayers that there is not even the tiniest fluff or gunk between the only wheel which has just contact to the rail on this side.

It will improve the pick up when all six wheel will have permanently contact to the rails .
What i have done here is written in chapter 7 of the principles of loco motive suspension und compounded with a little springing.
<!-- m --><a class="postlink" href="http://www.clag.org.uk/41-0rev.html#section7">http://www.clag.org.uk/41-0rev.html#section7</a><!-- m -->

In short terms:
- First axle wil become the rocking one.
- Second axle will be sprung loaded.
- Third axle will stay rigid.


[Image: dsc08960mwutw.jpg]
This simple piece of 1,2mm brass wire will become the central bearing for the first axle.


[Image: dsc08967miubt.jpg]
The bearings for axle 1 and 2 will be filed or milled so that:
- 1st axle is able for rocking
- 2nd axle is able to take sprung action
- the botton plate will also be modified to enable rocking or springing


[Image: dsc08978p7xee.jpg]
The modified running gear. Flanges were also reduced to NMRA Standards.
The leaf type spring is the "H" shaped piece.

[Image: dsc08970o1lnh.jpg]
The side rods.
As you see, this is a combination of continous and jonted. Here in this case the bore in the middle has an oval shape vertical! This enables the 2nd axle to travel up and down although the side rods are rigid.


Have a look what takes action now on the same spot:
[Image: dsc089458hkep.jpg]
[Image: dsc08946dyjnn.jpg]
[Image: dsc08947gukc1.jpg]
All wheels are permanently onto the rail.

Now this loco runs as good as it looks like. Even the slowliest crawl is possible and no fear of stalling. Good bye speed switching.
Now it is a Rangierlok / shunter / switcher who can do it's duty in a prototipical manner.


My two Cents

Lutz
Cheers Lutz
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#5
Wow, Lutz, that's an interesting idea!

I'm not trying to add springs to the MDS locos. I'm scratch building a mechanism, and am wondering if the advantages of having sprung drivers are worth the extra complexity.
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Kevin
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#6
From experience and past posts from others to the Yahoo Repower & Regear group, <!-- m --><a class="postlink" href="https://groups.yahoo.com/neo/groups/repowerandregear/info">https://groups.yahoo.com/neo/groups/rep ... egear/info</a><!-- m --> I'd say it's justified.

A properly sprung and/or equalized model will out-perform a rigid one.

If you build it and you're not happy, you'll wish you'd gone the extra steps(maybe not full equalization on the first one).

The standard design used on brass imports is simple and allows you to use available parts, like NWSL springs.

Correct balance and weight are also vital.

Dan M.

Quote:I'm not trying to add springs to the MDS locos. I'm scratch building a mechanism, and am wondering if the advantages of having sprung drivers are worth the extra complexity.
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