| 摘要 |
<p>PURPOSE:To discharge air naturally without impeding pump performance by boring on a piston an air vent hole opened to the displacement chamber of an oil hydraulic pump used for the lifting cylinder of a driver's stand, etc. CONSTITUTION:At least the upper opening section of a bore hole 1m opened inside a cylinder 3a to extract the air in a displacement chamber 3d is opened at a place equal to or higher than the height of the lower end face of a piston 3c at its bottom dead point. The cylinder 3a is arranged in the direction of a gravity force. Thereby, the air flowed into the displacement chamber 3d is gathered at the portion of the lower end face of the piston 3c, and when the piston 3 is lowered, the gathered air is pushed out into a reservoir through the bore hole 1m.</p> |
