What's New with Piston Rings

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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Johnlanark
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What's New with Piston Rings

Post by Johnlanark » Fri Jan 22, 2010 6:44 pm

As Den's suggestion, here's a new topic looking for input on materials. My old boat needed careful oiling when laying up to prevent corrosion between the iron rings and the iron cylinder bores. I know the big paddele steamer "Waverley" uses plastic rings on the air pump at least. Does anyone have experience on "new technology" piston rings on small steamers? John
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Re: What's New with Piston Rings

Post by artemis » Sat Jan 23, 2010 8:10 pm

Johnlanark wrote:As Den's suggestion, here's a new topic looking for input on materials. My old boat needed careful oiling when laying up to prevent corrosion between the iron rings and the iron cylinder bores. I know the big paddele steamer "Waverley" uses plastic rings on the air pump at least. Does anyone have experience on "new technology" piston rings on small steamers? John
:idea: When Al Giles was still working for Olympia Brewing Co as chief millwright in the 1960s, they were having trouble with the piston rings for gas compressors. As beer qualifies as a food, most lubricants (in 1962) were not allowed in contact. Al came up with the idea of using teflon rings. He made some up, installed same, and voila. Prior to this the rings would last maybe 1000 hours. Ring life increased dramatically to 10,000 hours. He then made piston rings of teflon for the compound in Crest. they lasted a loooooooong time. He also used teflon for piston and valve rod packing.

Another problem with piston rings is the vertical split (in whatever configuration) that allows the ring to be expanded and positioned over the piston. This "split" allows steam to move from the high pressure to the low pressure side of the piston, among other things. The clupet (pronounced "CLEW PAY") piston ring is the answer. Manufactured in Maryport, Cumbria, UK, there are several good references out on the web including address - they don't have a website. Google "clupet piston rings". Several SBA members use them and a number of automobiles in SACA also. The "Likamobile" engines also used clupet rings.
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Re: What's New with Piston Rings

Post by 87gn@tahoe » Sat Jan 23, 2010 11:35 pm

What about automotive piston rigs, such as Total Seal's "gapless" psiton rings?..

http://www.totalseal.com/

Thin and "low tension" so parasitic loss is a minimum. Rings are as thin as 1/16" and thinner! So that makes for a piston that doesn't need to be anywere near as thick.. Much lighter to boot! They seem to be good enough for 1,000+HP racing engines.. There would probably be less cylinder wear than even in automobiles, as they'd probably never even see 1,000 RPM in an EC (external combustion) engine .

I'm sure they can make them for any size, and give you some insight on proper gap clearences to a given operating temperature. Just order a bunch of "top" or "second" rings.. No need for the "oil" ring in an EC engine.

Many of their "non custom" rings come in sizes that are relatively common in steam engines as well... I.E. 4" is a common small block chevrolet bore size


It was just a thought..



OOPS! I might get banned for extolling the virtues of IC engine parts :D

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steamboatjack
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Re: What's New with Piston Rings

Post by steamboatjack » Sun Jan 24, 2010 10:32 am

John, the answer is NO there is nothing new and cast iron rings are far and away the best material. Years ago I tried hydraulic type seals using a material of appropriate qualities for the conditions... useless.
Also it is a myth that a significant amount of fluid gets past the gap in conventional rings, more fluid get past behind the ring at the change of direction in a double acting engine, either way if the ring is correctly fitted it is negligible. Having said that I use only Clupet rings as they are on the doorstep so to speak and Mr Smith the manufacturer will make any size, not to mention his vast knowledge on the subject.
Problems caused by inactivity of the engine can be reduced by use of plenty of cylinder oil and avoiding large drops in temperature during storage to avoid condensation and frequent turning over.

Air pumps always had "plastic" bucket rings a material called "ebonite". A modern material for this duty is "nylacast Oilon” or Tufnol carp brand, (allowance is needed for swelling in water for all these).

An interesting point concerning the Elliott Bay engine: - the original drawings specified plain solid ungapped rings on the pistons? In forty-five years I have never heard of this??? Needless to say I have used clupet rings on the pistons and no rings on the piston valves just water grooves.

Send me an e-mail if you need details of ring suppliers in the UK, or you can make your own, trouble here is getting a supply of centrifugally cast C.I. the usual mehanite stuff is ok but its easier to buy them.
Regards jack
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