@shitpisscum @icedquinn @paula8 @ube it's a shema of a napier deltic egnine. Basically 3 v engines arranged as opposing piston engines and also a 2-stroke diesel engine which is the hottest engine cycle there is. One of the cranks has to rotate in the opposite direction of the others to get the timings correct and they're all connected to a central shaft with gears as olis common with opposing piston designs but the contra rotating one has an extra gear to correct that which looks kinda funky.
The brits actually designed them for speed boats in ww2 because diesel is just way less dangerous to be around but they needed to cram as much power as possible into them because diesels are heavy, tha's wthy it's 2-stroke and opposing piston.
They've been later used in a bncuh of trains and even as pumps for stupidly large fire trucks.
Fun fact: the original military version couldn't start with ambient air pressure and needed an external compressor to start. Those versions where also prone to exploding on startup