| 摘要 |
PROBLEM TO BE SOLVED: To provide a driving force providing device for a tensioner silent and excellent in durability to give tensile force to an endless transmission belt such as a cam chain of an internal combustion engine. SOLUTION: This driving force providing device 20 of the tensioner the front end of which is made contact with a driven member and on which a pressing body 30 having a screw 34 is supported on a casing 21 free to move, a bearing member 25 is interposed between a rear part of a rotation shaft part 26 having a screw part 28 to be screwed on the screw 34 and the casing 21, and a spring 39 to energize the pressing body 30 in a direction to advance it and to provide the tensile force to the endless transmission belt 10 by pressing the endless transmission belt 10 in the tensile direction is devised. The device to also sets returning torque required to rotate the rotation shaft part, pushing force and returning torque to retreat the cylindrical pressing body at constant speed by overcoming energization of the spring 309 with the pushing force which is force of the pressing body 40 to project by energization of the spring 39 and in a state where a specified load is applied on the pressing body 30.
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