| 摘要 |
PROBLEM TO BE SOLVED: To absorb excessive torque applied to a reduction gear device without increasing the manufacturing cost of a power unit so as to prevent the reduction gear device from breaking down. SOLUTION: In a power unit 12 for a scooter type vehicle in which an engine 13 and a unit case 14 extending rearward are integrated, a rear wheel 15 is directly rotatably supported with the rear part of the unit case 14, and a reduction gear device 51 transmitting the power of the engine 13 to the rear wheel 15 side while reducing speed is housed in the unit case 14, at least two gears (for example a primary driven gear 48 and a secondary driven gear 50) are fixed to gear shafts (a driven shaft 44 and an axle 45) by press fitting. The press-in interference of the press-in parts A, B are set so that limiting torque TAmax, TBmax generating slip at the press-in parts A, B of these gears 48, 50 are in the range of 1.5-3 times the maximum drive torque TA, TB of the engine 13 applied to the press-in parts A, B.
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