AUTOMATIC SELF-CENTERING DRAW-DOWN CHUCKS with HERMETICALLY SEALED BODY type U-ASA II with 3 and 6 jaws linked by 2+2+2 having dimensions from dia.200 up to 900mm, used in the chucking of disc brakes, drum brakes, hubs, shafts, crown gears, differential carriers and other mechanical components from mass-productions in the automotive industry.