High torque screw head - has curved eccentric faces for engagement by tool

摘要

The screw head allows heavy torque to be transmitted from the tool to the shank, and has curved faces (1), eccentric to the screw axis (6), for engagement by the tool. There can be three such faces, formed in a recess in the head, and also on the outside, the centres of the faces lying on a pitch circle concentric to the screw, and whose radius is approx. half that of the intersection point of two faces from the screw centre. The tool can comprise a bar profiled to fit in the socket formed by the internal faces and/or a disc with a recess fitting around the external ones.