The Steamboating Forum

I have two of these links in the stephenson style valve gear on my 1902 Toledo that appear to have been babbitted at some point.

One of these links has a little more play then I like and I was considering repouring the babbit.

I see that a copper shim was babbitted in one of these two links. The other one may have had also had a copper shim and perhaps it wore off and fell away.

Is there a useful resource that explains the practical aspects of babbit work?

I can weld and solder, I have done a little brazing. I have watched videos of other people pouring babbit in much larger rotational bearings.

This website has at least 8 different babbit alloys available in small quantities, I'm not sure which alloy, or if any of them would work:
https://www.rotometals.com/babbitt-bearing-alloys/





The other option I was thinking of is to buy some stock and try to machine a replacement link.

-CB

You may wish to consider plastic bearing materials; I've had good luck with Delrin in this application. Oillite might also work well here.
If the loadings are very high you may need to choose something stronger, but the very slow rotative speed and intermittent motion makes plastic a natural choice.

- Bart

Are you sure it is Babbit? It could just be someone's bodge with soft solder by the looks. I'm rather with Bart in this one, convert it to what works for you, plastic? P/B? Oilite?

Mike Rometer wrote: ↑Thu Dec 09, 2021 10:04 am Are you sure it is Babbit? It could just be someone's bodge with soft solder by the looks.

It may be filled with solder, whatever it is it feels soft when you file it.

At first glance It looks like a slot was machined and then filled. But when you look closer, It looks like the geometry has features that are meant to hold the soft metal.

This engine was made just about 50 years before Delrin was invented. There is a 0% chance that I'm putting Delrin in this engine.

-CB
.

The shim in place is definitely a bodge. The rod end is an odd shape but I think that's to allow for different placements of the bore to change rod length without needing different casting patterns. Pouring Babbitt is easy especially when you can entirely fill the cavity and bore the hole without the need to have the shaft in place when pouring.

Here are some links that may be helpful. I used Magnolia when I poured the mains on the York.

http://wiki.vintagemachinery.org/BabbittIDGuide.ashx

https://www.google.com/url?sa=t&rct=j&q ... vP-kpKQh22

https://magnoliabronze.com/products/babbitts/

Cheers

Ken

I heated the one link to get the solder/babbit to come out.

It appears to be a milled slot that was filled with the soft metal.

It is hard to see it in the first photo, but it looks like they may have tried to mar the inside of the slot to give the soft metal something to hang on to.




-CB

If you insist on using soft metal again, I recommend you use Grade 2 Nickel-Babbitt, which is harder and lead free than other Babbitt alloys.
Fill the entire slot and bore to the required location and size. The harder Nickel-Babbitt will machine better than lead alloys.

Alternately, modify the oval opening to use positionable bronze half-bearings, per prototype designs.
Then adjustments can be made later when wear is detected.

Last year several of us successfully poured all new Nickel-Babbitt bearings for a 10-ton steam traction engine. Crankshaft is 3.5" diameter.
Better than new now. An interesting learning experience.
RussN

What is the diameter of the pin vs. the width of the slot? Bearing steel against steel on one side while bearing against Babbitt on the other makes no sense. Also, filling the entire slot with Babbitt is something never seen. Babbitt isn't used in a big block, because it doesn't have the strength to stand up to compression, it is poured in as a thin liner onto a block of harder metal filling the rest of the slot.

Here is a drawing of an adjustable wristpin end of a connecting rod. The slot is mostly filled with a steel wedge, a steel block, then two bronze bearing halves. If Babbitt were to be added, it would be added to the i.d. of the bronze bearing halves. Any more than that, and it would be pounded out of existence in no time.

https://www.flickr.com/photos/190507513 ... /lightbox/

What part of the Stephenson valve gear are these? Usually, SVG has no slotted links, other than the big one at the end of the eccentric rods. Are you sure that they aren't parts for something else that are meant to have that amount of lost motion? Perhaps pressed into service on Stephenson Valve Gear as a stop gap?

Kelly beat me to it with his drawing. I have a small stationary twin that has adjustable bearings. Someone at some stage had soldered the two halves of the small ends together, out of round (???). Folks do odd things sometimes. Granted it was fiddly to get together but a bit of patience did it. It is now adjustable again with a tapered wedge set with a nut.

Kelly Anderson wrote: ↑Fri Dec 10, 2021 6:35 am What is the diameter of the pin vs. the width of the slot?

1/4"pin. The slot is slightly wider, maybe 0.010" wider.

I think the slot shouldn't really be a slot, it should probably just be a 1/4" hole. On the otherside it is hole that should be around 0.320".

Likely whoever made this past repair did not have the time or skill to do better.

Kelly Anderson wrote: ↑Fri Dec 10, 2021 6:35 am What part of the Stephenson valve gear are these?

I'm not sure I know the correct name. These are the the rods that pull the expansion links forward and backward. The other end is connected to the shaft that is what the reversing lever rotates the 1/4 turn or whatever angle that is.
*Note only 1 of 2 installed in the image below*

Kelly Anderson wrote: ↑Fri Dec 10, 2021 6:35 am ... Are you sure that they aren't parts for something else that are meant to have that amount of lost motion? Perhaps pressed into service on Stephenson Valve Gear as a stop gap?

The grain on the castings matches the grain on the other parts in this engine. They do not appear to be identical castings to any other parts.

I understand the concept of an adjustable wristpin. It is probably beyond my machining abilities to achieve. There also doesn't appear to be the space to accommodate an adjustable wrist pin.

-CB