WRENCH OR SHIFTING SPANNER

摘要

A spanner may be a fixed open jaw, ring or shifting type, characterised in that each face of the spanner that engages a face of a hexagon nut or bolt, has a semi-circular groove in the face, the groove exceeding the dimensions of the apexes of the hexagon shape of the nut or bolt and having sharp corners where the groove meets the face. The groove can be engaged with the apexes of the nut or bolt hexagon shape as a firmer grip if very large torques must be applied, e.g. for loosening stubborn nuts or bolts.