| 摘要 |
PURPOSE:To eliminate the necessity of provision of a specific power transmitting gear to a journal portion of a crankshaft of a multicylinder engine for a motor-cycle to reduce the length of the crankshaft by forming on the periphery of a crank arm driving teeth for power transmittion. CONSTITUTION:When the invention is applied to a four-cycle four-cylinder engine placed horizontally on a body of a motor-cycle, crank pins 13 which are connected to con'rods 12 for pistons 5 of cylinders 4a-4d, four sets of crank arms 14a, 14b;- 17a, 17b which are located on both sides of the respective crank pins 13, and journal portions 18, are integrally formed on a crankshaft 9 by forging. The crank arm 15a corresponding to the second cylinder 4b is formed in a regular circle and is provided in a coaxial relationship with the journal portion 18. The crank arm 15a has in- tegrally formed on the outer periphery thereof driving teeth 19 for power transmission which are adapted to mesh with a drive gear 24. The crank arm 15 is induction hardened at the teeth 19 thereof. |
