With this tool from Buzzetti crankshafts can be pulled into the crankcase / housing half of the engine and mounted.
To do this, one of the two supplied threaded pieces (M10x1.25 and M12x1.25 thread) is screwed onto the crankshaft stub and clamped in the tool. Then the crankshaft is carefully pulled into the engine housing / crankcase by tightening the rear nut.