In addition to working on triples, I like old iron and help out at Rough & Tumble in Kinzers Pa at the working museum. The piston ring I'm holding is out of a 1913 vintage 485 hp Cooper engine that developed 21,000 ft lbs of torque. It was originally run on natural gas and was a pump for moving natural gas thru the pipelines. This engine plus an additional six others were in Medina Ohio.
Here's me with the piston ring

The single flywheel is 14' in diameter and weighs 22,000 lbs. It has a 21-1/2" bore and a 36" stroke and is a "Tandem Double Acting" each pair of pistons has it's own cylinder casting and cooled in the center.
View from the front ( click for bigger pics)


A couple pics of the compressor


Here's how you bring an engine that weighs 150,000 lbs to TDC so you can start it. It's started with compressed air , 165 psi fed thru 2" steel pipe. The guy pumping is priming the oiling system.
https://www.youtube.com/watch?v=mvBQSYRBzdAHere's it's running on propane. Both ends and the center are saddle mounted to support the weights of the piston assembles. The large eccentrics run the intake valves on the top and the exhaust on the bottom
https://www.youtube.com/watch?v=E1jLYz9TtTY Here's a view of the ignition system and the smaller eccentrics for the oiling.
https://www.youtube.com/watch?v=iUaLLfqZx9U Here's one I took two weeks ago from the flywheel side. If you listen closely, you can hear when the air is switched off and it starts running on propane ( just a few seconds after the video starts)
https://www.youtube.com/watch?v=UVYq8DO8L_k Jeff