Saturday, September 19, 2009
Weekend Steam
The "Marshall Corliss" used to pump water for the city of Marshalltown, Iowa. Midwest Old Threshers acquired this beauty in the late Sixties, and it is the largest steam engine in the machinery building at Mt. Pleasant. Taking pictures is usually difficult because of the crowds moving through the displays, but EJ and I got lucky this year and were able to take lots of photos and video just before the engine was shut down for the night.
The valve gear is what makes this a Corliss. The valves rotate rather than slide as in a conventional steam engine, and the quick cutoff of the intake valves is the throttling mechanism. EJ may do a post about this valve gear some day and fill in all of the necessary technical details.
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5 comments:
What would have been its normal operating r.p.m.?
- gsc1039
Dear gsc: I found everything but the answer to your question, so I will have to go back to Old Threshers again next year! I know that I have a snapshot of an information placard for this engine in my old photos, and finding that will be a rainy day project. We DO have a digital photo of a placard for a similar size engine. Another big Corliss in the building has a 13' flywheel, and was meant to operate at 150 RPM. The engine in the video has a 14' flywheel, so it would operate no faster than 150. This engine was purchased by Marshalltown in 1922 for $37,000. It could pump 6,750,000 gallons per day against 208 pounds of pressure. The high pressure cylinder is 22" bore, the low pressure cylinder is 44"; the cyliders have a 36" stroke. The flywheel is 14' diameter, and weighs 11 tons. It operated with 125 pounds of steam pressure; the pump has 504 valves; the engine delivered 137 million ft/lb of work per 1,000 lb of dry steam. The engine and pump are 35' long, 17' wide, and they weigh 130 tons. Eight semis trasported the engine and pump to Mt. Pleasant. The foundation required 140 yards of concrete built on 11 levels. It took volunteers at Old Threshers 4 years to complete the move and erect the engine.
Jeepers! That's more information than I know what to do with! It would be interesting to know what the efficiency of this setup was compared to the equipment which replaced it...but that too could wait for a rainy day! Thanks, Sam!
-gsc1039
Complex control systems using valves requires an automatic control based input of an actuator. The actuator strokes the valve allowing the valve to be positioned accurately and allowing control over a variety of requirements.
I checked your website, and I hope our readers do, too. Impressive. The actuator on these old engines the governor (rotating gadget with weights), which limits the intake of steam via a throttling valve on conventional steam engines. On Corliss engines, the governor breaks the link which opens the rotating intake valve, which is then shut rapidly via a link to the dashpot. The machinery is fascinating to watch. The intake and exhaust valves have separate eccentrics to operate them, and of course, there is no cutoff mechanism on the exhaust valves. Come back and visit TBS often; we post old machinery regularly.
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