Abstract: This invention related to an improved cam mechanism of low vibration air driven screwdriver, in particular, applicable to the clutch for the electric or pneumatic screwdriver in an effort to reduce the vibration to the minimum. The orbital surface of the cam body provides three segments of cyclic stroke, each stroke comprises the top dead point and the bottom dead point and each segment further contains four phases stroke, namely phase stroke A, phase stroke B, phase stroke C and phase stroke D. Each stroke of the orbital surface forms a recess for the catch ball to move. These two new designs are intended to reduce the vibration to the minimum and to cut the production cost in one way and to increase the friction area between the cam body and the ball so as to elongate the service life span in other way.

Abstract: A novel air-driven screwdriver is integrally designed to perform three functions, hole drilling, thread tapping and bolt tightening with special characteristic in which a passive inner gear assembly is employed as a driver to replace the clutch as used by the prior art. When the torque reaches at a specified level, the cam in the inner gear assembly will jump up and down, working similarly as the clutch, coupling with the torque spring and torque adjusting mechanism to control the output of the actual torque applied. This design eliminates the attachment of the clutch, shortens the overall length of tool, reduces the total weight and becomes more practical and reliable tool machine.