US Patent 7392711 Insertable strain gauge spanner

An insertable strain gauge spanner which comprises a spanner body having a rod body and a driving head insertable into the rod body; the rod body having a handle and an inserting opening at one end thereof; the inserting opening can be received the driving head; the rod body being installed with a strain gauge; a lower end of the rod body being formed as an inserting opening; the inserting opening being in contact with the strain gauge; thereby the twisting force from the driving head can be transferred to a sensing end of the strain gauge; the twisting force being displayed in a window of the strain gauge; and the driving head having an inserting end with a shape corresponding to that of the inserting opening; and the orientation of the driving head with respect to the rod body is adjustable.