| 摘要 |
<p>PURPOSE:To facilitate the manufacture of the product by inserting a synthetic resin made cylindrical unit provided with an annular channel on external surfaces to keep the dust prevention boots in positions, to the cylindrical part formed by scraping the internal surface of an open end of the cup shaped metallic piston for a little amount. CONSTITUTION:An internal surface of the open end of the cup shaped forged metallic piston 31 is either scraped or swaged simultaneously with forging to form the cylindrical part 13, to which the cylindrical unit 14 composed of the synthetic resin is inserted under pressure along with the metallic washer and jointed together. Then the external surface of the cylindrical unit 14 and the back metal of the friction pad 27 is buttjointed and an end of the dust prevention boots 30 composed of corrugated flexible materials is positioned on the annular channel formed on the external surface while the other end is positioned on the annlar channel made at the end of the opening of the cylinder 2a. Consequently, the proposal can prevent the dust from entering the sliding part of the piston 31 and cylinder 2a from outside.</p> |
