| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a piston with reduced weight, low manufacturing costs and excellent durability. SOLUTION: A piston 8 slidably inserted in a cylinder bore formed in a cylinder block comprises a head part 81 and a drum part 82, and the head part 81 makes slide contact with the inner peripheral surface of a cylinder bore throughout the whole periphery of the outer peripheral surface thereof. The drum part 82 is continuously connected to the head part 81 and the outer peripheral surface thereof comprises at least three partial peripheral walls extending along the slide direction of the piston 8 in the cylinder bore. The partial peripheral walls 82 are formed into a shape formed through integral molding together with other part and disposed in a position wherein movement of the drum part 82 in the cylinder bore in the direction orthogonal to the central line of the cylinder bore is impossible.</p> |
