Patent ID: 7178811

Claim:
A chuck comprising: collet sleeve having an axial hole running therethrough and at least one opening positioned axially at a midsection of said collet sleeve, said at least one opening in communication with said axial hole; a sliding member slidably received in said axial hole of said collet sleeve and having a screw segment at an end thereof; at least one linkage member inserted through said opening of said collet sleeve and connected with said sliding member at an end thereof; a collet received in said axial hole of said collet sleeve having a screw hole threadedly engaged with said screw segment of said sliding member; and a driving member fitted onto said collet sleeve for driving said linkage member and said sliding member to move, allowing said collet to reciprocate with respect to said collet sleeve; wherein said linkage member is a shaft provided with an end secured with said sliding member and the other end having a rack; said driving member is an annular sleeve rotatably fitted onto the midsection of said collet sleeve having a thread at an inner periphery thereof for threadedly engaged with said rack of said linkage member; and wherein said collet sleeve comprises a first annular groove at an outer periphery thereof; said driving member comprises a second annular groove at an outer periphery thereof for corresponding to said first annular groove of said collet sleeve; said driving member comprises a through hole, a plurality of metal balls inserted into said through hole to be received in said second annular groove of said driving member and said first annular groove of said collet sleeve, and a pin fixedly received in said through hole of said driving member.