| 摘要 |
A double-arm, sharply angled lever is pivoted at its fulcrum to the drive element of the clutch, and has one arm extending generally in a direction to the center of rotation of the driven element, and biassed by a spring force to engage the driven element. The fulcrum or pivot point of the double-arm lever is so placed with respect to the engagement surface of the arm of the lever with respect to the driven element, that the resulting force vector, resulting from the perpendicularly acting engagement force of the arm of the lever, in essentially radial direction, and the frictional force between the circumference of the driven element and the arm of the lever are located slightly behind the pivot point of the lever when the clutch is engaged, to effect self-locking of the lever arm against the driven element. The second arm of the lever carries, or is formed with a centrifugal weight and, upon rapid rotation of the driven element, moves the lever to swing outwardly, against the force of a spring, self-locking being overcome when the resultant force vector passes through and then in advance of the pivot point of the lever, providing for smooth engagement and disengagement of the clutch with positive, self-locking when the clutch is engaged. The position of the pivot or fulcrum point of the lever with respect to the resulting engagement force provides a toggle action, with binding force on one side of the toggle, and smooth, release/engagement at the other.
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