Re: "Jakuba's Compounding article in the Bulletin"
October 02, 2014 02:38PM
Jim
Off topic

On the Doble E valves did you ever try to estimate the blow by of the steam by the rings with 1200 PSI into the low side of the valve?
I noticed in Barry Herbert’s book the Tale of two Dobles he shows new valves with just two rings as original on the high side but added a three ring on the low side. I would have thought he would have added more rings to the high side as well.
Rolly
Re: "Jakuba's Compounding article in the Bulletin"
October 02, 2014 06:19PM
Rolly,

That ring leak rate was investigated by Warren Doble. Those were American Hammer cast iron step gap rings. I still have a box of them.
He measured seven pounds per hour per inch of circumference. They went to four rings in the last revision of the E valve to try to get the leak rate down. They also constantly changed the port locations to try to balance the engine torque. Why you never find a set of valves alike.

Jim
Re: "Jakuba's Compounding article in the Bulletin"
October 02, 2014 06:49PM
I wonder what Barry Herbert water rate is on E22 and if he is thinking about adding more rings. The photo of his new valves is on page 170 of his book.
That’s good information Jim thanks.
Rolly
Re: "Jakuba's Compounding article in the Bulletin"
October 03, 2014 06:57AM
Thanks Jim & Rolly,

I will look into these things. I had a "pause" in the action there for some steam brainstorming/discussion, but after a tiny strategic cut in the asking price the property sale suddently got extra-crazy, with multiple new bidders. Maybe I should hire one of those fast-talking auctioneers -- they always sound like "himmina hummina himmina, bleh, himmina hummina himmina, bleh" to me. And it might go to an all-cash buyer, meaning a 10/14-day escrow period to move/store a Mount-Everest-sized heap of antiques, machine tools, books, & junk halfway across the continent. Maybe starting a few days from now. Whew!

Peter
Re: "Jakuba's Compounding article in the Bulletin"
October 03, 2014 01:08PM
Rolly,

I forgot one thing. I was always told that ordinary step gap iron piston rings are a bad source of leakage with high pressure steam engines, so the more the merrier except for the added friction. Warren's measurements confirmed this, yet what else was there?
During the deep investigation of the Wankel engine, we discovered that Mazda had gone to a 2 mm thick rotor apex seal for better sealing than the older much thicker ones in the race engines.
So, investigation uncovered that there are spiral wound rings still available, they look like one of those Slinky toys. Multiple labyrinth sealing plus the contact of each turn against the cylinder wall. FEY is one source and there are others. I completely forgot I got the last set in town when I was driving my Stanley to stop the bad ring leakage. The new Doble engine will get these rings. Google labyrinth piston rings.

Jim
Re: "Jakuba's Compounding article in the Bulletin"
October 03, 2014 03:55PM
Jim I always make my own rings out of centrifugally cast Meehanite stock.
I use a step gap and like two rings in the same grove if I can 180 degrees to each gap. On a wide ring I cut a 1/16 groove around the center of the ring.
I have never got into all these other seals, and don’t know much about them but on the other hand I never worked with 1200 psi. My 1920 Stanley with my Derr boiler I ran with a 1000 psi but that was just two much for it and settled back at the 600 psi.

Rolly


Re: "Jakuba's Compounding article in the Bulletin"
October 04, 2014 05:41AM
Well I’ve been looking and getting an education on all these new style labyrinth piston rings. I can see the advantage used in a four cycle engine when the cylinder walls are getting washed with oil twice for every compression stroke.
I have to wonder though how effective they would be in a double acting steam cylinder running 750 to 1200F with just a pissey ass spray of oil in the steam.
I have the feeling a wide high wear material like Meehanite with a couple of oil grooves is not so bad.
Rolly
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