Drilling and/or percussion power tool

A drilling and a percussion power tool, comprising a tool holder;

• a housing;
• an air cushion percussion mechanism arranged in said housing and including a guiding tube, a piston reciprocating in said guiding tube, a striker reciprocating in said guiding tube, an air cushion chamber formed in said guiding tube between said striker and said piston;
• at least one control opening ventilating said air cushion chamber in an idling position of said percussion mechanism;
• a control part which in a percussion operation closes said at least one control opening for forming an air cushion in said air cushion chamber depending on a pressure on a treatment point;
• and at least one additional opening formed in said guiding tube for ventilation of said air cushion chamber and arranged forwardly of said at least one control opening at a side of a tool so that in a percussion operation said at least one additional opening is covered by said striker, depending on the tool inserted in said tool holder.