| 摘要 |
A ratcheting driver has a shaft rotatable relative to a handle, and a ratchet mechanism between the handle and the shaft. The ratchet mechanism has a body fixed to the handle. A spur gear coaxial with the shaft is mounted in the body so as to be rotatable about a common rotation axis of the shaft and the spur gear. First and second pawls are mounted on the body so as to be tiltable about axes parallel to the rotation axis and on opposite sides of an imaginary plane containing the rotation axis. Each pawl has a free end between its tilting axis and the said plane, and is tiltable between an engaging position, in which its free end intersects the tip cylinder of the spur gear and can abut against the flank of a gear tooth to prevent rotation of the gear in one direction relative to the body, and a non-engaging position, in which its free end lies outside the tip cylinder. A control member having first and second spring legs is movable to a first ratcheting position, in which the first leg urges the first pawl to the engaging position and the second leg urges the second pawl to the non-engaging position, a second ratcheting position, in which the first leg urges the first pawl to the non-engaging position and the second leg urges the second pawl to the engaging position, and an intermediate non-ratcheting position, in which both legs urge both pawls to the engaging position. A control sleeve rotatably mounted on the body, being captive between the handle and the body, is linked to the control member so that rotation of the control sleeve clockwise and anticlockwise from a given position moves the control member from the intermediate non-ratcheting position to the first and second ratcheting positions respectively.
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