PROBLEM TO BE SOLVED: To reduce early abrasion and bearing friction of a bearing metal of a crankshaft. ;SOLUTION: In this tunnel type bearing device of crankshaft, an intermediate tunnel hole 22 is formed in a bearing wall 2 of a crankshaft of a multicylinder engine, an intermediate bearing box 11 of the crankshaft is internally fitted in this intermediate tunnel hole 22, a bearing hole 16 is arranged in a front wall 2a of a crankcase 2, a rear tunnel hole 30 is arranged in a rear wall 2b of the crankcase 2 so that a rear bearing box 25 is internally fitted in the rear tunnel hole 30, the crankshaft is inserted from the rear tunnel hole 30, the intermediate bearing box 11 is fixed by using a fastening bolt, in the state where the box 11 is offset to lower side of the intermediate tunnel hole 22. The center of a bearing hole 28 formed in the rear bearing box 25 is made coincide with the center position of an outer circumference of the rear bearing box 25, and the center of a bearing hole 12 formed on the intermediate bearing box 11 is off set upward by almost half insertion space d, compared with the central position of an outer circumference of the intermediate bearing box 11.;COPYRIGHT: (C)2001,JPO
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