| 摘要 |
PURPOSE:To reduce the weight and facilitate repair, etc., by forming the bound ary surface of a crankcase body and a front side wall into each divided surface and forming the crankcase body to a casted article using a metal mold. CONSTITUTION:A crankcase 1 is constituted of a crankcase body 12, front side wall 2, rear side wall 4, and three independent parts, and the boundary surface of the crankcase body 12 and the front and rear side walls 2 and 4 is formed into each divided surface 14, 15. An intermediate side wall 3 is formed at the center in the longitudinal direction of the crankcase 12, and the front side wall 2, intermediate side wall 3, and the rear side wall 4 are arranged in the lengthwise direction of a cylinder separately in parallel in this order, and a supporting hole 10 for a crankshaft 8 is formed into concentric form over the side walls 2, 3, and 4. A crankcase 1 and a cylinder block 6 are shaped through the casting using a metal mold. |
