Abstract: A steam engine, which comprises a crankcase frame (1) arranged so as to rest on a foundation, a steam cylinder (25) supported by the crankcase frame, a cylinder bore (28) in the steam cylinder, a reciprocating piston (45) in the cylinder bore (1), a connecting rod (50), connected at one end with the piston by means of a piston rod (46), steam valves on the cylinder, a crankshaft (56) with crank webs (57, 65) supporting a crank pin (63), for the other end of the connecting rod a crank pin (63), and in the crankcase a plurality of crankshaft bearings (8) allowing rotation of the crankshaft.