A self-tightening chuck mechanism is disclosed. The chuck mechanism has a jaw mechanism with a jaw elements which are slidably disposed within corresponding channels defined in a rotatable body. A threaded socket member, which is configured to be rotated in first or second directions relative to the jaw elements is rotatably disposed about and engaged with the jaw elements. An impact assembly is configured to interface with the threaded body to apply anti-rotational forces to the socket member to prevent rotation of the socket member to close the jaws when rotated in a first direction and open the jaws when rotated in a second direction. The thrust bearing is configured to apply a first set of forces to socket member when the socket member is relatively rotated in the first direction and a second set of forces when the socket member is rotated in a second direction.