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I saw a ad some where for a adapter to run you steam engine on compressed air.

How many of you guys do that when you work on you engine?

Does the engine run different on air than it does on steam?

I was just wondering.
 

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JJ, I've used an inexpensive ($40)
air compressor I bought at WalMart a few years back, primarily for use on car & bike tires. It's self-powered
with a built-in rechargable 12-volt gel-cell pack. I've used it for doing valve adjustments (best done with the engine COLD!
) on my Accucraft Shay & Ruby; here it is in use on the 3-cylinder Shay...



To get the air actually into the boiler, I used one of the adapters furnished with the air compressor normally designed for applications like filling beach balls.
It's made of a relatively soft, rubbery plastic
- I just cut it slightly shorter, removed the brass water filler cap from the Shay's steam dome; and was able "force-thread"
it into the brass steam dome threads. The comparatively soft nozzle material was cut into by the much harder brass threads, with no harm to the steam dome threads themselves.
While not a perfect
air-tight fit (there is some air leakage
), it's adequate for testing / valve-tuning purposes.








I can pressurize the boiler to maybe about 20 PSI or so (even with the air leakage), enough to turn over the engine for valve adjustments.
Once I'm pretty sure I've got things the way I want, it's even possible to run the engine back-&-forth a few feet on air.
Then it's time for the actual steam test outdoors
-






- of course, running without the cab, I'll admit a "topless Shay"
looks a little wierd!




- There was a short article in Garden Railways recently about a standard plumbing fitting that is a perfect match
for the threads Accucraft uses for these boiler caps
- I'm going to check out the local Ace Hardware store for one to replace that leaky plastic nozzle!
Tom
 

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John, I used a compressor to set the timing on my two cylinder shay. It allows you to try many different settings until you are satisfied with how it runs in both directions. It did run a little different on live steam. A good tip I got from Dave Hottman was to disconnect the trucks on the shay to eliminate any possible binding from them. Any problem with them can be corrected at that time also. Nick Jr
 

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I have the same compressor that Tom does and it works well for testing and initial adjustments.

There are only two problems with it...

One is that it is very noisy.

But more importantly, one MUST be sure the boiler safety valves are in good working order. You don't want the boiler full of compressed air at a pressure greater than the normal working pressure; could be quite a dissaster if you over-pressurise it. This small compressor is realy not capable of overwhelming the safety valves if they are working, but could easily overpressurize the boiler/steam system if you are not paying attention to things.

If you use a compressor like this, it should be just capable of supplying enough air to run the engine and no more. Using a big commercial compressor could easily overwhelm the boiler and the safety valves and burst the boiler or damage other parts with too high of a pressure. A good pressure regulator can help in this realm; just set it for your boiler's normal working pressure. AND pay attention to the pressure reading on the boiler's pressure guage!

Another use of this compressor with coal or alcohol fired boilers is to use it, fed in through the feedwater valve, to run the internal blower to provide a draft while starting up the fire to get steam. But doing it this way can cause a lot of bubbling in the boiler if the feedwater inlet is below the water line and that adds a lot of air to the water and that is bad chemistry for a copper boiler with brass/bronze fittings. So I usually use it to supply air flow to a venturi stuck in the chimney to provide draft when starting the fire.
 

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Posted By John J on 02/03/2009 12:26 AM
I saw a ad some where for a adapter to run you steam engine on compressed air.

How many of you guys do that when you work on you engine?

Does the engine run different on air than it does on steam?

I was just wondering.



I use a compressor when checking the timing on my engines that I have purchased and need tweaking or the kits that I build, before attaching the boiler. You can get the timing set using a compressor nearly spot on (if not exactly spot on). The do run differently on steam; usually better. The steam will actually expand in the cylinder once everything is heated well, which, I don't think the air does very much at all. The other thing with steam is if there are any clearences that might be a bit close, they might be a bit tighter when things heat up. Don't forget to put oil into the line or directly into the cylinders as the displacment lubricators DO NOT work with air. (No condensed steam to displace the oil.)
 

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JJ,

I used a compressor to set the timing on my Gene Allen, 1 1/2 scale live steam Ten-wheeler. The only difference was that it was a 10 hp jobbie!
 

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I've had some success with a basket ball hand pump and the nozzle for beach balls. Only difference is that I am putting mine in to a smooth goodall valve. This pump can only make about 20 PSI, and I've been using it to check for leaks, initially, and hopefully to set valve timing later.
 

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You can use an industrial compressor just use a regulator as a throttle, just give it enough pressure to run and set the timing. I have the as supplied regulator on my compressor and have another regulator at the workbench, I can adjust the pressure conviently while I am attending to the engine at the workbench. Most engines will run on blocks at less then 5 psi, if you have to go much above ten then some work is needed.

Thanks
Steve
 

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Just a little explanation to my post. I needed a higher CFM than my home compressor would do, so I took my engine to work to run as a break-in. My ten-wheeler with a 1.5 inch bore and a 3 inch stroke only needed 5 pounds to run. It was just nice to have the volume of air. I used a regulator as the shop compressor was 120 psi or more. Nothing beats "industrial strength" compared to home tools.
 
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