Just google "glockenlager" for a lot of information. Basically, they are steel cranks that are pressed onto a square taper axle. BUT and a big BUT, they are not threaded for a conventional crank puller. There is a youtube video that says to remove them, you need a brave man and a big hammer. If that doesn't work, get a braver man and a bigger hammer. There is a tool that clamps into the crankarm with a threaded hole for a bolt to force them off the axle. It is a weird system, but was used for decades.