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 Post subject: Re: Mechanical Rod Packing
PostPosted: Thu Mar 09, 2017 7:04 pm 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 5102
Location: southeastern USA
If you have the conical ring and flat ring in combination, you probably have the King style. PM packings are double stacked flat rings, two segments per stack, and depend on flat springs inside a circular retainer to press them against the rod.

Rick, just don't do what I did and forget to use some mold release agent like acetylene soot before you pour the babbit.

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Thu Mar 09, 2017 8:58 pm 

Joined: Wed Oct 31, 2007 10:40 am
Posts: 64
Location: Chama, NM
I can vouch for the packing from CPI as being a good substitute for the original Paxton Mitchell product. We use it on the Cumbres & Toltec in all our engines. The stuff we use comes in two rings that are each 1/2" thick, which is comparable to the PM packing, so there is no adjustments needed in any of the components. You can eliminate the retaining ring as the CPI packing has springs built in.

Both the King and PM packing were supplied in different alloys. A softer babbitt, like you have, for saturated steam and a bronze material for superheated steam. The bronze alloy will work fine in a saturated application.

It appears from the pictures that you also have rod lubricator swabs on the outside of the packing gland. I have found that cotton rope or felt rod, available from Mc Master-Carr works well in those. The added lubrication will extend the life of both your rods and the packing.


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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 1:14 am 

Joined: Wed Oct 25, 2006 12:12 pm
Posts: 80
Location: Bremerton, WA
I wouldn't water jet packing or any bearing material as the garnet impregnated in the material is harder than any of the components. If you want to ruin an endmill or reamer as well, feed it into garnet.

Good luck.

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 9:26 am 

Joined: Sun Aug 22, 2004 12:15 am
Posts: 424
Yeh, I forgot about the abrasives in Water-jetting, so I guess that would only leave laser-cutting or stamping (from babbitt plate). Luckily Babbitt is soft enough a quality bench vise would have enough force for stamping (if you had no access to a press or iron-worker).
Rich C.


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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 9:59 am 

Joined: Thu Sep 22, 2011 4:29 pm
Posts: 921
Location: Youngstown, OH
The plan thus far is to water jet a piece of 5/8" plate with an opening corresponding to the shape of the outside of two segments, with allowances given for 3% shrinkage and for the width of a saw kerf to cut the segments after boring. I will cast it solid then bore it out to the finished size then cut into two pieces. I will also have the plate cut into two halves to facilitate removal of the casting from the mold.

That is my approach to solving the problem. Advice and suggestions are appreciated.


Attachments:
packing segments.jpg
packing segments.jpg [ 92.06 KiB | Viewed 1000 times ]

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 11:54 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1197
Location: Strasburg, PA
Hot Metal wrote:
I will cast it solid then bore it out to the finished size then cut into two pieces.

That is my approach to solving the problem. Advice and suggestions are appreciated.

If sawn in half after boring you will have huge leaks through the saw cuts.

Steam completely surrounds the packing inside the cylinder head, looking for any way out. Eight joints must be steam tight for the packing to be successful. Eleven is even better
1. The packing to the rod.
2. The split ring to the packing gland.
3. The split ring to the packing.
4. The packing gland to the cylinder head.
5 & 6. The joints of the split ring.
7 & 8. The joints of the packing.
9 - 11. The joints and fit of the front packing.

If any one of those joints has a gap or a piece of grit between one part and its mate, the packing will leak.

The rear packing is the more critical of the two, and often when replacement was needed, the better of the two old packings was moved to the front position, and a new one put into the rear position.

Image

We have long since given up on using metal for piston rod packing. Bronze filled Teflon works very well in this service, is easier to get (except for Babbitt) and is quicker to break in.

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 12:19 pm 

Joined: Mon Aug 23, 2004 2:09 pm
Posts: 343
Location: Los Angeles
The segmented packing is not bronze nor babbit originally. The babbit may be some shops answer to packing however these segmented parts were/are leaded copper. That is why when you clean and look at the piece it looks like copper. When making these pieces the end cuts are very specific so that they work correctly, that is as the I.D. wears the ends keep an alignment and always seal. When these pieces are made the ends are cut with EDM. I think that Historic Machinery Services Corporation, Robert Yuill has correctly made these pieces in the past. The price is not for the faint of heart though. Robert frandsen of steam services of America has success in adapting modern packing to locomotive cylinders.


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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 3:55 pm 

Joined: Wed Nov 23, 2016 7:05 pm
Posts: 29
Kelly -

Do you have a thoroughly modern finished packing/supplier like Parker FlexiSeal, or do you machine your own (+ source)?

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Fri Mar 10, 2017 6:44 pm 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1197
Location: Strasburg, PA
All or our engines use King packings, and we make them in house. IIRC, we did make a set of PM packings for someone.

If our engines used PM packings, we would be hard pressed to justify not using the CPI packings.

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Sat Mar 11, 2017 9:51 am 

Joined: Wed Mar 01, 2006 4:29 pm
Posts: 57
Location: Monticello, IL
When getting Southern 401 ready for service at Monticello, we had new old stock King packing we purchased from J. David Conrad for the piston rods and valve rods, as well as the old material. We took small bits of both to the University of Illinois's Materials Research Lab to determine what, specifically, it was. We did this to confirm the material so we could make our own down the road.

This was the Lab's response:

We performed the analysis of the Babbitt material from 401. It is (in atomic percent) ~ 12% antimony (Sb) in a matrix of ~ 88 % lead (Pb). No other elements show up in significant quantity, but must of course be present as trace impurities. From the metallurgical phase diagram, the above composition is right at the eutectic point, so upon cooling below 251 deg. C the liquid will neatly separate into small grains of almost pure Sb in a matrix of almost pure Pb. We found just that in area scans of the composition. Thus, it has the usual design approach for babbit metals: hard grains in a ductile matrix.


This was for both the new old stock King packing, and the old stuff we removed from the loco. Of course, this is a slide valve soak, so I would expect superheat locos to have, as Russ noted, a material with more copper/bronze in it.

Here is the Lab's informal report:

Attachment:
401 babbitt analysis.pdf [485.25 KiB]
Downloaded 26 times


Kent McClure


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 Post subject: Re: Mechanical Rod Packing
PostPosted: Sat Mar 11, 2017 2:20 pm 

Joined: Thu Aug 05, 2010 2:06 am
Posts: 127
I'd like to take a moment to thank everyone who has contributed to this thread. This info will be a great help to the C&NW 1385....MLD


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 Post subject: Re: Mechanical Rod Packing
PostPosted: Mon Mar 13, 2017 10:29 am 

Joined: Thu Sep 22, 2011 4:29 pm
Posts: 921
Location: Youngstown, OH
I went out to my garage to see what my Ames Unaflow engine used for packing. Its packing was made by American Metallic Packing Co. in Pittsburgh and looks identical to the CPI product. Alternating layers of packing and radial rings. Piston rod for the Ames is approx. the same diameter as the 58's rods so I can make an apples to apples comparison.

To those who use the CPI packing, how do you go about purchasing them? Do you have a contact at a distributor that you work with? Exploring all options.

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Wed Mar 15, 2017 9:15 pm 

Joined: Wed Oct 31, 2007 10:40 am
Posts: 64
Location: Chama, NM
Rick,

We purchase the CPI packing directly from the manufacturer. Cost is something like $150-200 per set I am told.

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 Post subject: Re: Mechanical Rod Packing
PostPosted: Tue Apr 18, 2017 4:17 pm 

Joined: Tue Apr 18, 2017 11:39 am
Posts: 1
Dave wrote:
The CPI products resemble the France Compressor packings I retrofit to a Shay when the Paxton Mitchell rings disintegrated a couple decades ago. I think we used a stack of 4 instead of two...... very pleased with the results. If you decide to cast your own, Jack Anderson used to cast his with a product called "diesel babbit" and had good service with them. There was a Paxton Mitchell hand cranked lathe that was sold for custom boring the packings for fast refitting while in the roundhouse that i wish I had one of today.


Dave, France Compressor bought Compressor Products International (CPI) around 2007, so they are indeed the same products.


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 Post subject: Re: Mechanical Rod Packing
PostPosted: Wed Apr 19, 2017 9:24 am 

Joined: Mon Aug 23, 2004 2:09 pm
Posts: 343
Location: Los Angeles
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