Opposed piston engines.

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Jul 26, 2004
New Bri-en, CT
The basic concept of an opposed-piston engine is so simple that it’s remarkable how long automakers have been ignoring it. In a traditional engine, each piston sits in its own cylinder, and combustion occurs inside the cylinder head, where intake and exhaust valves regulate the inflow of air and vaporized fuel and the outflow of exhaust. In an opposed-piston engine, there’s no cylinder head: two pistons move toward and away from one another inside the same cylinder, with combustion occurring in the in-between space at the moment of greatest compression. Without the cylinder heads, the engine is lighter, and the dual-piston action means compression ratios are higher, so it gets more bang for the buck.
Some animation. http://pinnacle-engines.com/technology.html
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Hello, Simpler at the intake and cumbustion end, more complex at the output end. However the efficiencies work out is OK by me but there is more weight with two cranks and two crankshaft lournals AND the gearing (chains etc.) to synch the power. Too bad they didn't include a drawing of an aircraft application. Kira
Hello, WOW! Who knew? Thanks for what I'll call "a turn-on". This was my very first look at the interesting articles section of BITOG. WAAYYY more interesting than freaks arguing over motor oils which are used in mostly identical circumstances all the time. Don't get me wrong, I love freaks. I will use the search first from now on. Kira
Everything old is new again... The British Doxford diesel engine connected the upper piston through links to the crankshaft. The U.S. Fairbanks Morse diesel had upper & lower crankshafts connected with a shaft & bevel gears. Lots of power in a confined space, but everyone I know who worked on them hated all the extra work to take extra stuff apart to do the usual jobs. Both were vertical engines. Do a Google search for images of both.
WAsn't the Fairbanks-Morse used in US WW-II era submarines? I seem to recall the submarine at Muskegon, MI has a 9 cylinder F-B diesel with 18 pistons. Did F-B use it in their locomotives too?
I was on a WW 2 era diesel submarine for about a year in 1961. It had a 38ND 8 1/8 Fairbanks Morse diesel. 8 1/8 inch bore and a 38 inch stroke opposed piston engine driving a dc generator.
They were talking about 300 hp per unit in the earlier part of the video, anyone know torque specs? Also what kind of RPM do they spin at? They said less inertial forces or rocking, almost none, which would lead me to think high rpm.
Hmmm...."sleeve valve engines" Sleeve valves were used in the 20s, but the increased machanical complexity (and therefor cost), as well as wear and the friction from all the sliding surface meant that poppet valves (what we now have) outperformed them...are they saying that modern oils, perhaps, cut down on the friction enough to make this practical???
There's a fair bit of research going on into rotary valves. Sleeve valves I don't see much future in.
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