| 摘要 |
A ball racket includes a head frame for racket stringing, a shaft unit including first and second tubes non-rotatably fitted to each other to be moved relative to each other along an axis, an actuator disposed within the first tube and having an actuating end and a shank body, an expandable shell disposed between the actuating end and the first tube, and a force transmitting mechanism disposed between the expandable shell and the first tube. Counterclockwise rotation of the actuating end causes the expandable shell and thus the first tube to expand radially so as to generate increased friction between the first and second tubes to thereby guard against relative axial movement between the first and second tubes. Clockwise rotation of the actuating end permits the first tube to axially move relative to the second tube so as to adjust the length of the shaft unit.
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