bearing material inside steam chest

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barts
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bearing material inside steam chest

Post by barts » Sun Jan 14, 2018 4:44 am

Hi folks -

Rainbow's engine has a really poor HP valve rod guide design, so I'm redoing that by making a much stronger guide bolted to the valve chest and adding a guide for the top of the valve rod in the steam chest. This is because due to the short height of the engine, the distance between the valve rod guide and the bottom of the steam chest is quite small. The material for the guide rod bushing will be oillite sintered bronze, but for the top of the steam chest I'd like to use a material I can thread 5/8"-18. Any suggestions? I'd considered making the top bushing from brass and babbiting it and reaming to size, but I'm not sure how it will deal with the ~350 F we have at 150 psig working pressure. Phosphor bronze is also an option.

Any ideas + rationale for this?

Thanks -

- Bart
-------
Bart Smaalders http://smaalders.net/barts Lopez Island, WA
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dampfspieler
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Re: bearing material inside steam chest

Post by dampfspieler » Sun Jan 14, 2018 8:54 am

Hi Bart,

i prefer gunmetal for that part. The valve rod should have a small flat part a bit longer than valve stroke to prevent it from vacuum in the chamber above the rod.

Here some Pics.

The Valve rod
FLS181kl.jpeg
FLS181kl.jpeg (115.34 KiB) Viewed 3262 times
Valve rod in place in valve chest
FLS184klsmall.jpeg
FLS184klsmall.jpeg (87.28 KiB) Viewed 3262 times
complete cylinder
FLS187klsmall.jpeg
FLS187klsmall.jpeg (111.54 KiB) Viewed 3262 times
The running engine - my little steam logging loco



Best Dietrich
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Kelly Anderson
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Re: bearing material inside steam chest

Post by Kelly Anderson » Sun Jan 14, 2018 8:40 pm

Cast iron will be fine.
It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work.
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