Main valve mechanism of compressed air nailing machine

A compressed air nailing machine comprising:

• a strike piston;
• a strike cylinder for slidably containing the strike piston;
• an air chamber storing compressed air;
• a ring-shaped flange portion formed to project from an outer peripheral face remote from an upper end edge of the strike cylinder;
• a main valve formed in a ring shape and slidably arranged on an upper side of the ring-shaped flange portion;
• a cylinder seal for covering surfaces of an upper face of the ring-shaped flange portion and an upper end portion of the strike cylinder from the upper face of the ring-shaped flange portion over to the upper end portion of the strike cylinder;
• a piston stop including an outer peripheral edge portion arranged on an upper side of the strike cylinder, damping the strike piston at an upper dead center position and formed to extend in a lower direction along an outer peripheral face of an upper portion of the strike cylinder;
• an air intake valve seat formed at a position of the cylinder seal opposed to a lower end of the main valve;
• an air exhaust valve seat formed at a lower end of the outer peripheral edge portion of the piston stop;
• and
• an air intake/exhaust path formed between an outer peripheral face of the cylinder seal and an inner peripheral face of the outer peripheral edge portion of the piston stop for guiding compressed air from the main valve to an upper end edge of the strike cylinder.