Author Topic: Repairs for Samhongsa steam- those pesky bearing springs  (Read 989 times)

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u18b

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Repairs for Samhongsa steam- those pesky bearing springs
« on: May 29, 2014, 01:25:22 PM »
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I hate to be known as the "spring guy"....

But I wanted to give you a heads up if you own any Samhongsa steamers.

I've helped a guy and discovered that his problem is that he is missing some of the tiny springs that go under the bearing blocks on a Sammy.

Apparently, this is a very common problem if your Sammy is ever taken apart.

Last time this subject came up, someone suggested trying the springs in watch band pins.
I did that.  Those springs are indeed pretty small, but they are VERY stiff-- being designed to compress over the *entire* one inch length.

We need a spring that adequately compresses over about 1 mm.

Well, without a good solution, I'll be going back to get some springs made from the company that made my pantograph springs.
Not many people bought my pant springs extras (hey, I still have some if you want any).

But when it comes to these Sammy springs, I would think that a LOT of people would want some.

Yes, they would be a little pricey, but so far, it will be the ONLY game in town.
And if it fixes an expensive brass steamer, wouldn't about 3 bucks per spring be worth it?

I don't have prices yet.
In fact, I don't really want to be the spring dealer for Railwire (I don't have time).

But if there is someone else here who would have some interest, speak up.

I guess in the worst case scenario, people could send in a Self-addressed envelope.  And that would save some of the hassle. (I should have thought of that before).

If you own a Sammy, I figure you need at least 2 spare springs per loco.
They get lost very easily.

If you already have a working spring solution, please speak up.
I and others need a source.

Ron Bearden
CSX N scale Archivist
http://u18b.com

"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

nstars

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #1 on: May 29, 2014, 05:44:32 PM »
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With our Samhongsa steamers the springs have all been removed when we rebuild the chassis. Most of te Samhongsa steamers (with the bearing springs) were bad running engines and needed a new chassis inserted between the old one. In most cases the springs are also useless while they were either too stiff or too soft. Springs too stiff are useless and springs too soft have an impact on the running quality while the drivers could move too much upwards due to the force in the coupling rods. Using no springs has resulted in very good running engines  :)

Marc

peteski

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #2 on: May 29, 2014, 05:58:57 PM »
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I have never encountered a brass steam loco where the bearing springs (is this a new term?) were too soft.  Wouldn't that be equivalent to not having the springs at all (since they would be constantly fully-compressed)?  But I also do not have as much experience with brass models.

Usually those springs are too stiff which also results of them not functioning as desired, resulting in the drivers  being solidly suspended in the frame (not being able to travel upwards when needed).

From both examples, the soft springs would be a better alternative, allowing the drivers to drop down into dips in the tracks, keeping electrical contact.

Best springs would be ones which would allow the drivers to sit half-way between the top and bottom limits of the bearing travel. But that would be difficult to achieve. They would have to be custom-made for each specific model (their stiffness would depend on the number of drivers, loco mass and by how much weight the leading/trailing trucks support  But as I mentioned, I think that soft springs would be a good compromise.
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SP-Wolf

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #3 on: May 29, 2014, 05:59:52 PM »
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With our Samhongsa steamers the springs have all been removed when we rebuild the chassis. Most of te Samhongsa steamers (with the bearing springs) were bad running engines and needed a new chassis inserted between the old one. In most cases the springs are also useless while they were either too stiff or too soft. Springs too stiff are useless and springs too soft have an impact on the running quality while the drivers could move too much upwards due to the force in the coupling rods. Using no springs has resulted in very good running engines  :)

Marc

This is very interesting info-- what are you using in place of the springs-?

Thanks,
Wolf

mmagliaro

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #4 on: May 29, 2014, 07:33:29 PM »
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What is the diameter, length, and fully-compressed length of these springs?
I'm on the hunt. 

Thank you.

victor miranda

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #5 on: May 29, 2014, 09:48:18 PM »
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all,
at 3 bucks a spring that is 24 dollars for a 2-8-0.

ow.

and even so, I think I would get a set.
so YES.

onward...
at one point I lost one of these for long enough
that I started planning to build a spring roller for my lathe.
I am very happy that I found the spring!

I have to reiterate what Marc  has said.
In the locos I have tinkered the springs are all stiff enough
that they may as well not be in there. lift any one wheel
and you will lift the loco.

and I tried soft springs.
The loco runs far better stiff.

this next part is conjecture on my part because I have not done it.
I suspect that finding a way to equalize the drivers
would be far more effective than separate springs.

victor


mmagliaro

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #6 on: May 30, 2014, 12:11:56 AM »
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Here ya go:



$6 for 24 springs.

Here they are installed in a Key PRR H10



I can't say whether they work better or worse.  The engine ran good before this, and it runs good now.
They fit in really nice, and they definitely have a softer feel than the originals.  As you can see, the original springs are
not all that well made/wound.  Also, with a pair of tweezers, I can lift this driver set a touch without lifting the engine,
which I cannot do with the other drivers, so I think these are an improvement.   But like I said, I don't have any scientific evidence to back that up.  It runs good either way.


« Last Edit: July 03, 2017, 07:38:29 PM by mmagliaro »

peteski

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #7 on: May 30, 2014, 01:05:40 AM »
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Very clever Max! Awesome find!
--- Peteski de Snarkski

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victor miranda

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #8 on: May 30, 2014, 01:35:37 AM »
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!!!!

the loco still sits at the high mark?

..... and you can lift just one driver.

sounds perfect.

now to hunt mchenry springs.

victor

mmagliaro

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #9 on: May 30, 2014, 02:25:30 AM »
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It sits perfect, from what I can see. 
And yes, when you put them in, you will immediately feel that they are a little softer and they let the drivers
lift a little easier.

Bear in mind, I only replaced the back two on this engine.
But then, that's what people are likely to do, replace just the missing springs, not all of them.
I think you should at least replace them in pairs so the springs on a single axle are the same.

Before I posted this, I ordered another pack of 24, because I figured you guys would scour the internet and
clean them all our wherever they may be.   But it doesn't look like they are an "unavailable" item, so they
should be relatively easy to find.  eBay had them, and the hobby shops like Klein's had them.

I had them because I noticed a pack of these in a "scraps" bin at a train show and thought, "Wow, those are some
pretty darn small springs, and they are not the super-light micro-trains springs.  I bet I can use them someday."


I had forgotten how nice this Key 2-8-0 runs (with a Kato diesel motor in it, and all-wheels-live trucks in
the tender, that is).   But it sure is a speed rocket.   If I were to work on it again, it would have to
have a gearhead.
.. and right after I typed that, I looked at my SP&S 2-8-0 book.  Bad news for Pennsy fans.
The SP&S had 15 class N-2 2-8-0's which were former GN 2-8-0's.  They were built by Baldwin, complete
with Belpaire fireboxes, and almost identical in proportion to the Pennsy H class.  Even the valve gear and cylinders
look very close.   They were the most numerous of the SP&S
2-8-0's and lasted on the roster into the 1950s.  Looks like a kitbash will be coming in the future.
I was wondering how I would make an SP&S 2-8-0.
(Max wouldn't chop up a Key brass engine, would he?  Would he?  .... you bet he would.)





nstars

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #10 on: May 30, 2014, 06:52:48 PM »
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I have never encountered a brass steam loco where the bearing springs (is this a new term?) were too soft.  Wouldn't that be equivalent to not having the springs at all (since they would be constantly fully-compressed)?  But I also do not have as much experience with brass models.

Usually those springs are too stiff which also results of them not functioning as desired, resulting in the drivers  being solidly suspended in the frame (not being able to travel upwards when needed).

From both examples, the soft springs would be a better alternative, allowing the drivers to drop down into dips in the tracks, keeping electrical contact.

Best springs would be ones which would allow the drivers to sit half-way between the top and bottom limits of the bearing travel. But that would be difficult to achieve. They would have to be custom-made for each specific model (their stiffness would depend on the number of drivers, loco mass and by how much weight the leading/trailing trucks support  But as I mentioned, I think that soft springs would be a good compromise.

Victor,

You're correct that in most cases the springs are too stiff. In that case the springs are in fact useless and you could have done without them.

Using softer springs sounds nice to assure the wheels remain on the track. However, in most cases the drivers on a brass steamer are powered by the side rods. Normally the side rods are horizontal, but when one wheel is lower than the other, they may have an angle. In combination with the horizontal forces on the side rod the angle may even result in pushing the driver up of the track instead of the spring pushing it down on the track. This is further exaggerated when you consider that drivers on both sides are quartered. As a result the side rods on both sides apply a different force on the driver, which may result in a wobble of the axle. In theory it is possible to find a perfect balance between weight in the driver and the stiffness of the spring (it's done in real life  :) ), but in scale the margins are so small, that in my opinion finding this balance will be more or less a miracle. That's the reason why we don't bother about the springs. We removed them or leave them in place when they are stiff enough.

This is very interesting info-- what are you using in place of the springs-?

Thanks,
Wolf

Nothing, the axle of the drivers is fixed in place in such way it still can turn freely without much vertical movement. When steam engines are powered through the side rods we have found out, that limiting the movement of the axle will improve the running quality of the engine.

It is a completely different situation with steam engines where the drivers are powered by gears. In that case the side rods have more play and with strategic placement of the gears the drivers can really be pushed onto the track. Perfect examples of this solution were the old Rivarossi steamers like the USRA steamers.

Marc

mmagliaro

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Re: Repairs for Samhongsa steam- those pesky bearing springs
« Reply #11 on: May 30, 2014, 07:08:57 PM »
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Marc makes an excellent point.  If the springs are too soft, there would be a tendency for drivers to bob up and down, or even slap against a rail now and then as the rods propel them around.  The spring has to be such that the driver can just barely move up and down.  Whatever "just barely" means, I don't know... .003"?  .005"?   It can't be much.

We also know from people experimenting by putting a piece of masking tape under the bearing blocks in a steam loco on
the traction tire driver that .005" makes a huge difference in traction and running quality. So I'd say that any spring that
allows "just more than zero" movement is the right spring.   Years ago, I kitbashed a 4-6-0 from Rivarossi frames, and
it couldn't pull much.  My rear driver was propelled only on the rods and it tended to float on the rods.  I put springs
into the frame on that one (tiny Microtrains coupler springs).  I thought it would do nothing except perhaps make the engine look
better as it went down the track because at least the rear drivers would stay down and not bob up.
But to my shock, that tiny bit of spring force allowed the engine to pull 25 cars up a 2% grade (instead of something less than 10).

You are all correct: we are splitting hairs and dealing with incredibly tiny forces here.  Getting it right is hard. 
Leaving the springs out is probably just as good as replacing them with McHenrys, if not better.  But at least you've got an alternative.
The McHenrys are cheap, available, easy to install, and at least for now, they seem to work.