| 摘要 |
PURPOSE:To reduce the generation of white smoke and oil drop in the captioned crank bearing, by forming a recessed groove extending radially onto the inner wall surface of a crankcase and thereby positively utilizing lubricating oil for lubricating the crank bearing. CONSTITUTION:During the rotation of a crankweb 4a, lubricating oil adhered to the inner wall surface of a crankcase 5a is collected into a recessed groove 8 through the side wall of the crankweb 4a. And the lubricating oil flowing down the inner wall surface of a scavenging passage 7 is collected into the recessed groove 8 from the upper end part of the recessed groove 8. Thus col lected lubricating oil flows into a bearing 6 through the notch groove 9 of an outer ring 60 for being served as lubrication. Owing to this constitution, the absolute quantity of the supplied lubricating oil is reduced, and thereby the quantity of the lubricating oil being supplied to a muffler from a combustion chamber is lessened so that the generation of white smoke and oil drop is reduced.
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