An adjustable wrench includes: a head having a first fixed jaw; a handle extending away from the head; a selectively positionable second jaw; an adjustment mechanism that includes a rotatable shaft, an actuator, and a gear train operatively coupling the shaft to the second jaw; the shaft having an external spiral groove and disposed at least partially in the handle; the actuator slidable relative to the handle and engaging the groove; first and second flanges spaced from one another and each circumferentially surrounding the shaft; and a retainer disposed between the flanges and engaging the shaft so as to limit movement of the shaft parallel to the handle longitudinal axis in two directions via abutment with the first and second flanges. Such a wrench may have a proof torque of at least the minimum level set forth in ASME B107.8, 2003 revision. Other wrenches are also disclosed.