Air compressor

An air compressor comprising:

• a chassis forming bearing seats on opposite side portions thereof;
• a motor, mounted to the chassis;
• a transmission set arranged between the bearing seats, comprising a centrally located clutch and having two opposite ends which is respectively coupled to an eccentric rotation member by an axle, each eccentric rotation member having an outer side face to which a shaft is mounted for being rotatably supported in the bearing seat, each eccentric rotation member being coupled to a crank arm, the clutch being operatively coupled to the motor for being driven to continuously rotate;
• a plurality of extendible barrels each operatively coupled to a moving end of the crank arm, each barrel having an outer circumferential surface forming alternating circumferential troughs and circumferential ridges, each of which is provided with a reinforcing ring, each barrel having a top on which an air inlet port is centrally mounted and a bottom on which an air outlet port is centrally mounted.