SCREW FASTENING MACHINE TO WORK WITH COMPRESSED AIR

PROBLEM TO BE SOLVED: To provide a screw fastening machine which can perform screw fastening with lesser thrust force and at a high speed, allows a slackening operation simply with a single unit of machine, and ensures an enhanced operating capability. SOLUTION: A screw fastening machine includes an air motor 2 capable of rotating both in the regular and reverse directions through controlling of the air flow by an operational valve 24, and even after a rotary slide member 7 and piston part 13 operated by a push lever 26 and the valve 24 have reached the undermost point, the piston part 13 is pressed downward always without releasing the compressed air existing on the piston part 13, and if in this condition, a driver bit 16 is engaged by a screw head and the body 1 is pressed, an air hole 56 in communication with the air motor 2 is opened which should put a rotor 3 in reverse rotation.