Abstract: A novel threaded fastener is provided having an elongated shank portion with a first end and a second end opposed to the first end, and a helical thread in the form of a continuous helical ridge that is arranged on an external surface of the shank portion. The helical thread includes an asymmetrical threaded portion that has a progressively increasing axial displacement of a pressure flank of the helical thread between the first end and the second end of the shank portion, and a progressively decreasing axial displacement of a non-pressure flank of the helical thread between the first end and the second end of the shank portion. When assembled, the novel threaded fastener has a clamping force distribution that is evenly distributed on the helical threads along its axis in the direction of force transmission reducing the risk of self-loosening and increasing fatigue resistance.

Abstract: Screws are provided which have a longitudinal axis and include a threaded shank and a head wherein a socket is formed to be engaged by a wrench and having a pluri-lobed outer profile comprising a series of lobes circumferentially offset and separated by a series of circumferentially offset protrusions of the head. Each protrusion is delimited by two flanks and a front length joining the radially inner ends of the flanks and is convex and symmetrical with respect to a center axis radially oriented with respect to the longitudinal axis. The front length is formed by a center face and two inclined side faces each of which joins the radially inner end of the respective flank with a respective end of the center face, which is oriented orthogonally with respect to the center axis of the protrusion. Pluri-lobed wrenches adapted for use with such screws are also provided.

Abstract: Screws are provided which have a longitudinal axis and include a threaded shank and a head wherein a socket is formed to be engaged by a wrench and having a pluri-lobed outer profile comprising a series of lobes circumferentially offset and separated by a series of circumferentially offset protrusions of the head. Each protrusion is delimited by two flanks and a front length joining the radially inner ends of the flanks and is convex and symmetrical with respect to a center axis radially oriented with respect to the longitudinal axis. The front length is formed by a center face and two inclined side faces each of which joins the radially inner end of the respective flank with a respective end of the center face, which is oriented orthogonally with respect to the center axis of the protrusion. Pluri-lobed wrenches adapted for use with such screws are also provided.