US Patent 7363839 Driving tool having rotatable coupling

A driving tool includes a tool stem having a non-circular spatial engaging member and having one or more flat surfaces, a tool shank having a non-circular socket opening and having one or more curved surfaces for pivotally receiving the spatial engaging member of the tool stem and for allowing the tool shank to be selectively tilted relative to a longitudinal axis of the tool stem. A control ferrule is slidably engaged onto the tool shank and slidable and engageable onto the tool stem for retaining the tool shank in line with the longitudinal axis of the tool stem and for preventing the tool shank from being tilted relative to the tool stem to other angular position.