Reversible high impact mechanism

摘要

A reversible rotary wrench includes an impact mechanism for applying intermittent torque impulses to a load. The mechanism includes a rotatable shaft having an axis and adapted to be coupled to a motive source, a rotatable anvil for coupling to the load and having a pair of anvil ears, a tubular hammer substantially coaxial with the shaft and having a pair of hammer ears engageable with the anvil ears and a rotatable tubular drive coupling member substantially coaxial with the shaft. The mechanism also includes a first helical cam structure coupling the drive coupling member to the shaft, a second helical cam structure coupling the drive coupling member to the hammer, and a spring biasing the hammer axially toward the anvil to engage the hammer ears with the anvil ears. When the shaft is rotated in a first helical direction and torque exerted by the anvil on the hammer exceeds a given threshold, the sleeve rotates and the first cam structure responds to rotation of the shaft to move the hammer axially away from the anvil thereby disengaging the hammer from the anvil. When the shaft is rotated in a second direction and torque exerted by the anvil on the hammer exceeds a given threshold, the second cam structure responds to rotation of the shaft to move the hammer axially away from the anvil thereby disengaging the hammer from the anvil.