Crankshaft surrounding structure for four-cycle engine of motor vehicle

摘要

A radial ball bearing (21) is set in the first main bearing portion (2a) of a crankcase (2). A radial roller bearing (22) is set to the second main bearing portion (2b) of the crankcase. A crankshaft (4) is rotatably supported by the radial ball bearing and radial roller bearing to the crankcase. An oil jet nozzle disperses coolant which cools a piston (12) in the second main bearing portion.