Woodwind instrument with key mechanism perfectly closing holes

A woodwind instrument for generating tones through a vibrating column of air, comprising:

• a tube having an inner space where said vibrating column of air takes place and plural holes connecting said inner space to the atmosphere;
• and
• a key mechanism including a linkage fixed to said tube and plural keys supported by said linkage over said plural holes and changed between respective open positions at which said holes are opened and respective closing positions at which said holes are closed,
• each of said keys having
• a pad cup connected to said linkage and formed with a recess,
• a deformable pad received in said recess and held in contact with a periphery of said tube defining associated one of said holes at said closing position,
• a adjusting shim inserted between said pad cup and said deformable pad, if necessary, in order to cause said deformable pad to be held in contact with the entire periphery of said tube defining said associated one of said holes at said closing position,
• a fastener connected to said pad cup and exerting force on said deformable pad for pressing said deformable pad and said adjusting shim, if any, to said pad cup and
• an automatic regulator provided in association with said fastener and causing said force to be substantially uniform over a contact surface between said fastener and said deformable pad.