Etkinlik

The most common type of Power Driver Screw Anchor Socket Type is a tapered plastic tube that’s inserted into a closely fitting drilled hole and tapped flush with the surface with a hammer. A hole in the center of the tube receives the screw and, when tightened, it expands the tube radially outwards gripping the screw anchor against the wall of the hole. Typically, the tube has slits in the base to facilitate its expansion and ribs on the sides to prevent its rotation when tightening the screw.

Screw anchors were invented by John Joseph Rawlings, a British Engineer in 1910, who had been contracted by the British Museum to attach electrical fittings without causing damage to their masonry walls. In response to the absence of any alternative to chiseling a hole and hammering in a wooden block to nail or screw into, Rawlings solution was based on the concept, “expansion means grip”.