POWER TOOL AND METHOD OF OPERATING AN AUTOMATED DRILLING OPERATION

摘要

A power tool includes a pneumatic motor with an output shaft, a spindle that is drivingly connected to the output shaft via a drive gear to provide a rotational movement to the spindle and via a feed gear to provide a translational movement to the spindle. A cylinder that governs the gear transmission to the feed gear is arranged to be translated between a retraction gearing position and an advancement gearing position. The retraction gearing includes a retraction torque limiting coupling adapted to be released when an operational torque (T) exceeds a retraction threshold torque (TR) in order to terminate retraction. A lock mechanism is arranged to selectively block the cylinder in the retraction gearing position through engagement between a tooth of a ratchet on the lock mechanism and a shoulder on the cylinder. The lock mechanism assures that the cylinder is kept in the retraction gearing position during an initial phase of the retraction of the spindle.