The main-bearing halves (4) for the crankshaft (1) are formed in the crankcase (3), and onto them detachable caps (5) forming the other halves are secured in a first plane (T1). A bridge-piece (12) extending in the lengthwise direction of the crankshaft is screwed (11) in a second plane (T2) to the caps. Tie-bolts (7) passing through the crankcase extend into the caps. The cap for each main bearing (2) is a separate component, and the tie bolts screw into it. Further screws (13) secure the bridge-piece detachably to the crankcase in the second plane. The first screws can be in line with the tie bolts in the lengthwise direction (L), while the second ones can extend into the crankcase sidewalls (9). The tie bolts and first screws can be between the central plane through the crankshaft and the second screws.
