Patent attributes
A shearable fastening device (1) has a shearable fastener (2) having a plurality of screwthreaded portions (3), a head portion (4) which is connected to the screws threaded portions (3) via a first predetermined weakening (5) and further predetermined weakenings (6) in the form of cross-section constrictions are provided between the screwthreaded portions (3), as well as an internal recess (7), wherein the internal recess (7) extends from the head portion (4) at least into the region of the predetermined weakenings (6). At least one stepped predetermined weakening (8) is formed by its shear-off torque (aNm) being smaller than that of the next predetermined weakening further away from the head portion (4) and the shear-off torque (aNm+1) at the next predetermined weakening closer to the head portion (4) rising again with respect to the shear-off torque (aNm) of the stepped predetermined weakening (8). The shear-off torque of the predetermined weakenings (6) on the portions without the stepped predetermined weakening (8) increases continuously in the direction of the head portion (4), and a force transmission element (9) is insertable into the internal recess (7) of the shearable fastener (2). The force transmission element (9) in the inserted condition extends from the head portion (4) so far into the internal recess (7) such that the force transmission element (9) bridges the stepped predetermined weakening (8).
