| 摘要 |
PURPOSE:To prevent a wound power transmission device from over tension, by making the titled device into structure giving predetermined tension force always through bouncing action of a tension spring and hydraulic pressure action of a hydraulic pressure chamber. CONSTITUTION:A hydraulic gap eliminating unit U possesses a cylindrical housing 8 formed on a main body E of an engine unitarily, a cylinder 9 is slided within the housing 8 ascendably and descendably, and a plunger 12 delimiting a hydraulic pressure chamber 14 is arranged within the cylinder 9. A tension spring 20 in the inside of the hydraulic pressure chamber 14 presses down the cylinder 9 and gives appropriate tension to a belt 3 through a bell-crank lever 4 and a pressure roller 6. Although the cylinder 9 is apt to be pushed up through the pressure roller 6 and the bell-crank lever 4 when tensile force is acted upon a slackening side 3b of the belt 3, retreat of the pressure roller 6 is controlled by hydraulic pressure of the hydraulic pressure chamber 14 as a valve hole 16 is closed by a check valve 17. As the hydraulic pressure of the hydraulic pressure chamber 14 leaks through a gap to be made by sliding action, tension shock can be absorbed. |
