11 here the threaded rod 17 and the annular part 20 with the internal thread 22 serve as the spindle drive 13 the external end of the threaded rod 17 includes a respective geometry for example the shape of a hexagon in the cross section so that a torque can be applied upon the threaded rod 17 for example via a pneumatic screw and thus the threaded rod 17 is set into a rotary motion about its longitudinal axis this way the threaded rod 17 is moved inwardly i e according to the illustration in fig1 towards the top due to the engagement of the external thread 18 of the threaded rod 17 with the internal thread 22 of the annular part 20 with the motion of the threaded rod 17 the piston 11 also performs the motion according to the illustration of fig1 upwards because the piston 11 is fastened to the threaded rod 17 in fig2 the fixing agent 5 is already pressed into the space between the anchor tube 3 and the stone 28 i e the anchor tube 3 is fastened to the stone 28 in a substance to substance fashion particularly by way of gluing.