O Rings for a CliShay

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littleevan99
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O Rings for a CliShay

Post by littleevan99 » Fri Aug 15, 2014 7:57 pm

On my CliShay, we are using O rings that are intended for a turbocharger. The only thing about them that I don't like is that they are tight enough that significant force has to be used to move them. Is there a good source for rings that work well with live steam engines?
1.5" scale CliShay
2.5" 20 ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99

10 Wheeler Rob
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Re: O Rings for a CliShay

Post by 10 Wheeler Rob » Fri Aug 15, 2014 8:34 pm

The groove depths are different for dynamic o ring seals than for static. See the on line Parker Hand book. Viton is usually the best choice for our hobby. For piston seals the cylinder bores need to be really smooth, they will wear real fast.

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David Powell
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Re: O Rings for a CliShay

Post by David Powell » Fri Aug 15, 2014 10:31 pm

I have given up on using O rings and have gone back to using soft packing. Both O rings and iron piston rings seem to need much more effort to move them than properly fitted pistons( Parallel round bores and pistons fitted with 1-2 Thous clearance per inch of diameter cold) packed with proper steam engine packing. Worse than that O rings suffer terribly if the cylinders are cast iron and they are allowed to rust up , even a short while out of use without pumping a lot of oil into the cylinders will cause rusting enough to rapidly wear the O rings. Have you ever seen red water come from draincocks if an engine is pushed along a week after being steamed and the cylinders have NOT been flooded with oil after use? Regards David Powell.

RET
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Re: O Rings for a CliShay

Post by RET » Sat Aug 16, 2014 8:06 pm

Hi,

As is said above, Viton seems to be best choice for our service. The one thing that you need to remember is that rubber expands a lot with temperature, so you can have a situation where a piston will move fairly easily at room temperature, but because of the expansion of the rubber, it will lock up solid at steam temperatures.

I have found that if you make piston grooves so the "O" ring just slides in with no side play and has just 4 to 7 thousandths interference on the diameter at room temperature, the rings will work well. Remember, the "O" ring seal is self energizing, so once the initial seal is made, you don't have to worry about it.

On cast iron you will have to replace them every year or two depending on how much service they see, but in a bronze bore, they will last much longer.

Dave is right. They don't like rust. Its abrasive and wears them fast.

Just my experience.

Richard Trounce.

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Chris Hollands
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Re: O Rings for a CliShay

Post by Chris Hollands » Sat Aug 16, 2014 10:42 pm

You also have to allow for oring hardness ,their is varying types useally 70 to 90 duro ,70 being soft and 90 bring quite hard,this will affect the operation of what it is being used for especially on smaller diameters.
the harder the more resistance to movement

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DianneB
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Re: O Rings for a CliShay

Post by DianneB » Sun Aug 17, 2014 4:55 am

In conversation with Parker last year, they recommended AFLAS for low pressure steam service (100 PSI) as piston rings.

I used the Parker handbook for dimensional clearances but found that a little less compression gave me smoother and easier running with no blow-by.

I did learn one thing about O-rings in this climate up here - don't move your engine when it is -30C :shock: I had to put new rings in my American after moving it midwinter. (Not surprising, really. Wont do that again LOL!) Other than that, I am getting great service from the AFLAS O-rings.

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littleevan99
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Re: O Rings for a CliShay

Post by littleevan99 » Sun Aug 17, 2014 10:21 pm

Thankfully, where I live at in California it doesn't get colder than 20° in the Winter time.
DianneB wrote:
I did learn one thing about O-rings in this climate up here - don't move your engine when it is -30C :shock: I had to put new rings in my American after moving it midwinter. (Not surprising, really. Wont do that again LOL!) Other than that, I am getting great service from the AFLAS O-rings.
1.5" scale CliShay
2.5" 20 ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99

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littleevan99
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Location: Northern California
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Re: O Rings for a CliShay

Post by littleevan99 » Sun Aug 24, 2014 9:14 pm

The O ring issue has been solved. My grandfather just made new ones out of cast iron, they seem to be working rather well.
1.5" scale CliShay
2.5" 20 ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99

kapullen
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Re: O Rings for a CliShay

Post by kapullen » Wed Aug 27, 2014 7:36 am

Evan,

If your grandfathers rings don't work out, this company
has cast iron rings for a very reasonable price.
They are located in Elkton Maryland.

http://www.ringspacers.com/

I have no connection other than being a satisfied customer.

Kap
Fadal Turn, Fadal Vmc 15, Prototrak 16 x 30 Cnc Lathe, Pratt and Whitney 16 x 54 lathe, Pratt and Whitney Vertical Shaper, G & E 16" Shaper, B & O Electric turret lathe, 36" Doall band saw,
Enco B.P. Clone, Bridgeport CNC Mill, Delta 12" Surface Grinder.

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