The Steamboating Forum

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

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 Valve rod in place in valve chest complete cylinder The running engine - my little steam logging loco



Best Dietrich

Cast iron will be fine.