THE CORLISS ENGINE
When I stir up old memories of engines and their vicissitudes, my favorite always turns out to be the Corliss Steam Engine. When a person said "Corliss", they were referring to the type of valve action used in connection with a steam engine. The basis of the theory was a slow running engine, usually not more than 100 RPM, with a stroke of about three times the cylinder diameter. A typical slide or piston valve engine would have a cylinder diameter only a little less than the length of the stroke. There were many companies that used this same principal with various, and sometimes quite unique, variations.
One of the best known was the Hamilton Corliss, made by the Hooven Owens Renschler Company of Hamilton, Ohio. These engines were most commonly known as "Hamilton Corliss Engines". I remember two old Hamilton Corliss engines that I operated, in 1937. One was 18 x 48 and the other was 14 x 42. They were both built in the late 1800's and were in a Paper Mill in Three Rivers, Michigan. The small one was belted to an Alternating Current Generator and the larger one was belt connected to the Beater Room Lineshaft. This lineshaft was the source of power for the Beaters and the Jordans.
The smaller engine had a 14 ft. flywheel that also served as a belt wheel, and the larger one had a 14 ft. flywheel and a 10 ft. belt wheel. Both engines were single cylinder, single eccentric, girder frame construction.
The speed of the Corliss engine is regulated by a releasing valve arrangement, that allows steam to enter the cylinder at boiler pressure, as opposed to a throttling governor, that is found in other systems. With the slide (grid iron) or the piston valve, the governor throttles the steam, only allowing enough pressure to enter the cylinder to keep the speed up. There are many variations of this throttling system, such as the flywheel governor that automatically controls the stroke of the steam inlet valve. The Corliss valve operates entirely different. The engine's speed is controlled by the amount time that the inlet valve is allowed to remain open. The engine governor only positions a trip device that lets the steam valve close when sufficient steam has entered the cyl_inder, at boiler pressure, to maintain speed. This releasing action only applies to the steam inlet valves. The exhaust valves open and close with a fixed relationship to the position of the piston, within the cylinder.
Some Corliss engines are equipped with two eccentrics, one for the steam valves and one for the exhaust valves. This allows a more precise adjustment of the valve timing and results in a more efficient overall operation. It did, of course, cost more to build an engine with two eccentrics. Efficiency meant very little to an engine that was used in a paper mill, the reason being that the exhaust steam was used to dry the paper and in most cases there was not enough of it, so the engine exhaust was supplemented with live steam. The energy that was derived by passing the steam through an engine, was almost free, because none of the latent heat was removed, only the pressure had been reduced.
Most of the Hamilton Corliss engines that I encountered were what was known as "girder frame" construction. That meant that the only frame that the engine had was a cast iron girder that connected the cylinder to the crankshaft bearing and housed the cross head and its guides. This made a very simple, but highly effective arrangement.
The Hamilton used the rocker type valve while the Nordberg and some of the others, used a poppet valve, like an automobile.
Another peculiarity of the Corliss, is the way that they are started up and shut down. You don't just open the throttle and let her go, neither do you just close the valve and go home. To start one you first be certain that the reach rod is disconnected from the valve gear. This is the rod that connects the eccentric, on the crankshaft, to the valve mechanism. Provisions are made for the connection and disconnection of this reach rod, while the engine is rolling.
Because of the relatively long cylinder, they require more warming up than most engines. You first insert the "starting bar" into a hole in the wrist plate of the valve gear, so that you are able to open and close the valves by hand. You then open the throttle, just a crack, and rock the gear, back and forth, several times to let steam in and out of each end of the cylinder, warming it gradually and evenly.
When you feel that you have the cylinder warmed up properly, you give it a little more steam and let it roll over center, changing the valve openings at the proper times, with the starting bar. When you get it rolling along, pretty good, you release the reach rod and let it make it's connection with the valve gear. You then gradually bring the engine up to speed, at which time the governor will take control.
To shut one of these single cylinder engines down, the start-up procedure is essentially reversed. After all of the load possible is taken off, the throttle is closed and the engine is allowed to coast down to almost a stop. You then disengage the reach rod from the valve gear and insert the starting bar. With the gear in a neutral position (both steam valves closed), you crack the throttle open a little, and as the crank goes over dead center, at either end, open the steam valve at the opposite end of the cylinder. This will close the exhaust valve on that end as well as let in a little steam, so that the piston will come up on compression and stop. If it should roll on over center, just let it go, reverse the valve positions and catch it on the opposite end of the stroke.
It is not absolutely necessary to follow this procedure, but if you don't and it stops on, or real close to, either dead center, you might have a problem rolling it far enough to get it started again. Not only that, but if you were to leave one on or near center, the person who had to start it up, the next time, would probably shoot you.
When I started in the power operation field, about 1934, there were still many steam engines being used. I am only putting these things on paper because in the relatively short time that I have been here, these steam engines have been drastically reduced in numbers. I am sure that there are many of them still in operation, but I would wager that, of those still running, the most of them are operated for sentimental reasons rather than for practical purposes.
During the time that I was employed by the Mutual Boiler Insurance Company (1942 thru 1947) I saw, inspected and supervised the repair of a great many engines of every size and type that you could imagine. There were engines that drove air compressors, ammonia compressors, paper machines, pumps, lineshafts, and just about anything else that was required to rotate or reciprocate. I am thankful that I have had the privilege of living and working, intimately, with the steam engine. I saw, and was a part of the down fall of the steam engine and the rise of the steam turbine and the electric motor, in industry. Surely not the beginning of the down fall or the beginning of the rise, but I did experience a large part of the transition that has now, just about eliminated the steam engine as an effective prime mover, in industry.
If I had written down the names of all of the steam engines that we had insured, in the Cincinnati District of the Mutual Boiler Insurance Company, when I had the chance, this would have been much more satisfying, to me. Just a few of the makes that I can remember were Ball, Nordberg, Hamilton, Chandler and Taylor, Skinner, Fitchburg and no telling how many more. Let that be a lesson for you young people; write down the things that you encounter before you get so old that you can't remember dates, names, places and events.
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