Abstract: The present invention is directed to an improved hand tool for using one hand to grasp a workpiece between a first and a second jaw of the hand tool and adjust the force applied to the workpiece. The hand tool includes a first arm and a second arm, the second arm is operably linked to the first arm so as to cause relative motion of the first and second jaws upon motion of the arms. The hand tool further includes a control arm having a first end pivotably linked to the first arm and a second end pivotably linked to the second arm at a moveable pivot location. The control arm is configured to control relative motion of the first and second arms into and out of an overcenter lock position. Movement of a force adjustor located on the second arm in a first direction moves the moveable pivot location so as to increase the level of force required on the second arm to move the control arm into the overcenter lock position.

Abstract: A self-adjusting pliers is operable to grasp a workpiece between an upper jaw and a lower jaw. The pliers includes an upper arm having a first end and a second end, with the upper jaw at the first end. A jaw arm has a first end and a second end. The second end of the jaw arm is pivotably connected to the upper arm at a main pivot adjacent to the second end of the upper arm, so that the first end of the jaw arm is movable in a circular arc relative to the main pivot. The lower jaw is at the first end of the jaw arm in movable facing relation to the upper jaw so that the workpiece may be grasped between the upper jaw and the lower jaw. An engagement mechanism releasably engages the jaw arm to the upper arm at an engagement position responsive to a movement of the jaw arm relative to the upper arm and responsive to a size of the workpiece grasped between the upper jaw and the lower jaw, to thereby prevent rotation of the jaw arm relative to the upper arm.