| 摘要 |
In this mechanism ( 7 ) a moving hook comprises a body ( 20 ) provided with a nose ( 202 ) for bearing against a corresponding knife ( 14 ), and a flexible blade ( 21 ) secured to the body so as to be capable of moving relative thereto and designed to interact with a retaining lever ( 16 ) belonging to the selector device. The selector lever ( 16 ) forms a ramp ( 313 ) over which a portion ( 214 ) of the resilient blade ( 21 ) slides when the hook ( 13 ) is moved in the vicinity of its top dead-center position. The ramp on which the selector lever slides is shaped in such a manner that the component (F<SUB>A</SUB>+F<SUB>B</SUB>+F<SUB>C</SUB>) parallel to the travel direction (X-X') of the moving hook ( 13 ) of the resultant of the forces (R<SUB>A</SUB>, R<SUB>B</SUB>, R<SUB>C</SUB>) acting on the flexible blade ( 21 ) when in contact with the ramp ( 313 ) in the vicinity of the top dead-center point of its travel and at the beginning of its downward movement (F<SUB>14</SUB>), is directed downwards.
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