Heavy Machinery.  Aside from the crisp beauty of B&W photography using film (can digital equal this yet?) one can be thrilled by the aesthetic of technology here, but it is all overwhelming somehow, too....a puzzlement....appreciating the these machines as aesthetic objects, but also wondering how it all works?  As a system?

 

 

I have some video somewhere that I shot of an older version of these engines, with less shrouding and more exposed moving parts. It's quite impressive to see all that massive machinery moving in perfect sychronization. I should digitize the video if the tape hasn't died from old age yet, and post a clip.

 

These big internal combustion engines are only slightly evolved from the huge steam engines that were their immediate predecessors in industrial settings that required enormous amounts of power. They are built with pairs of cylinders placed end-to-end rather than side-by-side like an automotive engine, and each cylinder has a cylinder head, valves and ignition at both ends so that power is applied to the piston in both directions.

 

A common piston rod runs through both cylinders, passing through seals where it passes through the cylinder heads. The piston rod and pistons are hollow, and water is pumped through the inside of the rod and pistons to keep them cool. This photo:

 

 

shows the piston rod emerging from the cylinder head of the second cylinder. The rod travels back and forth 36 inches when the engine is in operation, at a speed of about twice per second. 125 revolutions per minute may seem slow compared with modern automobile engines that turn in the thousands, but with that much mass it's pretty impressive.

 

The horizontal shaft that runs along the left side of the engine is a camshaft that operates the valves via pushrods that can be seen angling upward and downward. Intake valves that admit a mixture of air and natural gas are on top of the cylinders, and exhaust valves are on the bottom. The square boxes located at intervals above the camshaft, with tubes coming out of them are lubricators that are driven by the camshaft and distribute metered amounts of oil to the various moving parts.

 

The engines were started by admitting compressed air into the cylinders to bring them to near operating speed, and then turning off the compressed air and turning on the gas. Once they were rolling, the flywheel inertia did the cranking.

 

I think these engines were installed about 1937. They may have been among the last of the tandem horizontal engines produced. The design goes back to at least the early 1900s. Tandem engines were built by Worthington, Cooper-Bessemer, Mesta, and probably others I don't know about, and were used in pipeline stations, municipal and private industrial electric plants, steel mills, and powered the San Francisco cable cars before they were replaced with electric motors. I think that took place in the 1950s.

Thank you mechanical engineers!!!!!!!!!!