| 摘要 |
<p>PURPOSE:To prevent a cylinder inner surface from being marred by burrs that will be left on the surfaces of a piston after mold opening and to prevent the sealing from becoming defective, by forming the guide section of the piston, which corresponds to the surfaces where the parting lines of molds are located, to have flat surfaces so that spaces are formed between the cylinder surface and the guide section. CONSTITUTION:The piston 14 of a master cylinder 10 is integrally molded of a resin material, and has two guide sections 15, 16 that will abut and slide on a hole 13 in the cylinder body 11. The guide section 15 on the first side is provided with the flat surfaces 15a, 15b on the diametrically opposite sides. A parting surface P should be located at approximate centers of the flat surfaces 15a, 15b. A first cup 18 and a second cup 19 are respectively mounted to the left of the two guide sections 15, 16. A back-up ring 20 is positioned between the first cup 18 and a first side guide section 15, and this back-up ring 20 prevents the first cup 18 that will be deformed from biting into the flat surfaces 15a, 15b.</p> |
