Adjustment mechanism for adjusting depth at which pneumatic nailing machine drives nails into workpiece

A pneumatic nailing machine for driving a nail into a workpiece, the pneumatic nailing machine comprising:

• a main body;
• a nose provided to the main body, the nail being protrudable from the nose;
• a trigger pivotally supported to the main body for starting a nail driving operation;
• a push lever vertically movably supported to the main body, the push lever having a lower tip portion positioned near the nose and an upper tip portion positioned near the trigger, the push lever being divided into an upper section having a lowermost end and a lower section having an uppermost end;
• a drive bit supported in the main body and movable in an axial direction thereof, the drive bit being moved along the nose upon manipulation of the trigger;
• and
• a nail driving depth adjusting mechanism for controlling a distance between a lower tip end of the nose and a lower tip end of the push lever when the push lever is pressed against the workpiece, the nail driving depth adjusting mechanism comprising:
• a shaft portion rotatable about its axis, the shaft portion being positioned adjacent the trigger;
• a knob portion connected to the shaft portion for rotating the shaft portion about its axis;
• a first cam lobe provided to the shaft portion and having a first cam surface engageable with the lowermost end of the upper section;
• and
• a second cam lobe provided to the shaft portion and having a second cam surface engageable with the uppermost end of the lower section, contour of the first and second cam surfaces being arranged to simultaneously move the lowermost end and the uppermost end away from each other in accordance with a rotation of the knob in one direction and to simultaneously move the lowermost end and the uppermost end toward each other in accordance with the rotation of the knob in an opposite direction.