| 摘要 |
<p>PURPOSE:To improve the working-oil filling efficiency by forming an annular oil passage between a small-diameter piston part and the large-diameter hole of a cylinder opening when a master cylinder piston is at a retreat position and allowing a hydraulic chamber and a supplied-oil chamber to communicate through the annular oil passage. CONSTITUTION:The rear-part piston 3 of a master cylinder M is equipped with a small-diameter piston part 35 at the front and a large-diameter piston part 36 at the rear. A rear-part hydraulic chamber 5 is formed in a small-diameter hole 32 in front of the small-diameter piston part 36, and a rear-part supplied-oil chamber 11 is formed between the both piston parts 35 and 36. A piston cup 9 is installed onto the front edge surface of the small-diameter piston part 35 is separated from the small-diameter hole 32 when the rear-part piston 3 is at a retreat position, and an annular oil passage 37 is opened to allow the rear-part hydraulic chamber 5 to communicate to the rear-part supplied-oil chamber 11. The piston cup 9 closely contacts with the small-diameter hole 32 when the piston 3 is at an advance position, and the annular passage 37 is closed and the both chambers 5 and 11 are cut-off.</p> |
