That could also be the root of the problem that appeared to be worn bushings.

I also noticed this as well

Yeah, I agree. You can see the rod isn’t straight and true @ 11:11 or so, as Keith is unscrewing it.

I understood you OK. And I ein't that smart. Is it ein't or ain't or neither?

As Keith pointed out, welding cast iron makes for brittleness. Vibration is ALWAYS present, to some degree. The weld held up for 25 years, which is not exactly shabby.

@@eliduttman315 That still doesn't explain the original failure. There is obviously some misalignment somewhere and for now I would start by straightening the valve rod which is bent.

Yes, I was musing as to what the failure story was. I noticed that the rod which screws onto it is bent, which is either a symptom or a possible cause, and I wonder if the gland was ever overtightened.

@@eliduttman315 25 years is a long time but the engine was probably fired only a few times per year. Still, something is causing that part to fail as several have pointed out. Love Keith’s knowledge and expertise in old technology.

Can’t. Remember, the casting shrinks by a significant amount when it cools so any casting made from an original will be too small.

@@whodat90 i think cast iron shrinks only 1%, if the inside ends up 1% too small, it can be machined to the correct size, and if the outside ends up 1% too small, it doesn't really matter, and cracked area can be be modified prior to casting to make it way stronger...

1/8" per foot

@@anthonyraffin1034 1/8" per foot should be very close to 1%

I'd wager somebody stepped on it in the last 110 years.

Looks to me that there is a definite alignment issue that is putting downward pressure on that sealing gland. Each time the valve rod moves through the gland it’s being forced through at slight angle not parallel to the mating surfaces of the valve and the upper plate of the steam chest and the porting surface in the cylinder. This creates a stress on the sealing gland body that repeats with each stroke of the valve. Eventually the stress creates micro defects in the metallic lattice structure, and these defect vacancies coalesce into voids and the voids further concentrate the stress which leads to cracks forming. This is the mechanism for fatigue cracking. Unless the alignment issue is corrected the repair will fail again as repetitive cycles stress and relax the brazing. A bent valve actuating rod could be the source of the alignment issue.

I suspect the completion of the HBM restoration project is on the critical path for the stoker engine to be worked on again... The first time I saw that stoker engine case, I thought to myself "this is an ideal application for a small HBM...". Then Keith bought one...

I kinda chuckled when Keith had help with the steam chest (?) but didn’t have help with the cast cover that looked like it was twice as heavy. I wondered when he took that cover off why he didn’t have any help.

Counter-intuitively, beefing up a design could actually make it more likely to break! These engines often will have weak points designed into them such that in the case of a failure it doesn't destroy itself. For a 100 year old loco it's not doing so badly, I would expect the new part to last at least another 100 years again and maybe even longer with the high quality materials and processes we have available to us today

Valve bodies were a wear point. Remember these engines weren't designed to last for over 100 years they had a service life of around 30 to 40 years before being retired and scrapped. These things are literally older than the engineers thought they'd make it.

It's possible to anneal the cast iron to take out the brittleness. The nickle would still be there and might still be a problem though.

OR, the bent rod caused the crack, or recrack I should say.

Does he have more keys than Mr Jingaling, Keeper of the Keys?

Nice link. I worked in Gray & Ductile foundry. The molecular composition of the cast iron does indeed change. How they (in your link) slowly brought up the heat in the casting was smart.

It is much easier to consult the original documents than it is to reverse engineer a part especially when you've got a 100+ year old part. This steam chest's counterpart has decades of wear and tear from high pressure steam ( which will eat through through cast iron, as it did in another episode on this locomotive ), corrosion and abrasion, maintenance via machining and boring out of irregular surfaces, field modifications, and other factors in this locomotives history unknown to the current operators.

Fact of YT life, unless you use AdBlocker, the Brave browser or pay YT money every month. Creators get very little of the advertising revenue (shame - where would YT be without them?), hence sponsorship, merch and Patreon - can't blame them for wanting to cover the cost of their time and equipment. I doubt a large percentage earn their living this way.