Air damper

An air damper comprising:

• a cylinder;
• a piston adapted to reciprocate in said cylinder;
• said piston having spaced flanges on an outer periphery thereof defining therebetween an annular recessed portion;
• a sealing member slidably movable in said annular recessed portion between at least first and second positions, said sealing member slidingly contacting an inner peripheral surface of said cylinder, said sealing member and said piston cooperating to form air chambers on both sides of said piston;
• communicating means comprising a notched portion in one of said flanges, and a groove in a bottom of said annular recessed portion extending from a predetermined position in said annular recessed portion to said notched portion to communicate or not to communicate with said air chamber formed on both sides of said piston depending on the position of said sealing member in said recess;
• said cylinder having a portion of reduced interior diameter in the vicinity of one end of said cylinder, said portion gradually decreasing in interior diameter toward said one end to gradually increase frictional force between said portion of reduced interior diameter and said sealing member in order to obtain a gradually increasing damping effect.