Patent ID: 7144342

Claim:
A string pulling head structure of a racket stringer, comprising: a first string chuck and a second string chuck fixed with each other and a first chucking plate and a second chucking plate disposed between the first and second string chucks, outer faces of the first and second chucking plates respectively attaching to inner faces of the first and second string chucks, inner faces of the first and second chucking plates being respectively a first chucking face and a second chucking face, the first and second chucking faces defining therebetween a gap, the inner face of the first string chuck being formed with more than one first slot, the outer face of the first chucking plate being formed with more than one first slot mated with the first slot of the first string chuck, multiple ball members being accommodated in the first slots, the inner face of the second string chuck being formed with more than one second slot, the outer face of the second chucking plate being formed with more than one second slot mated with the second slot of the second string chuck, multiple ball members being accommodated in the second slots; a first antiwear slat disposed on outer side of the first slot of the first string chuck to seal the outer side of the first slot and another first antiwear slat disposed on inner side of the first slot of the first chucking plate to seal the inner side of the first slot, the first slats serving as the bottoms of the first slots, the first slats being inclined by equal inclination angle but in reverse direction, whereby the depths of two ends of the first slots are unequal to each other; and a second antiwear slat disposed on outer side of the second slot of the second string chuck to seal the outer side of the second slot and another second antiwear slat disposed on inner side of the second slot of the second chucking plate to seal the inner side of the second slot, the second slats serving as the bottoms of the second slots, the second slats being inclined by equal inclination angle but in reverse direction, whereby the depths of two ends of the second slots are unequal to each other.