the doctor 30 is located on an imaginary connecting line of the axes of the two drag bearings 20 and 21 when using the doctor 30 no moments occur around the axis of the second drag bearing 21 consequently in spite of the dynamic load on the doctor 30 torsional vibrations can be avoided another advantage arises from the fact that the blade tip is flush with the axis of the first drag bearing 20 as a result of this arrangement it becomes possible to remove the dynamic loads acting on the blade without the creation of moments in the robust stand 5 of the support of the paper machine which is not shown here as it is well known such doctors wear during use now after the wear of the doctor 30 has exceeded the permissible tolerance paper production is interrupted and the pneumatic cylinder 25 of the swiveling device 24 is loaded in the reverse direction as a result of the translation movement of the cylinder roll 29 of the pneumatic cylinder 25 the distance between the two linking points 22 and 23 is increased by a certain amount therefore the lever 4 performs a swiveling movement in the clockwise direction around the axis of the second drag bearing 21 thus the blade supporting beam 2 which is non rotatably connected to the lever 4 also turns in the clockwise direction around the second drag bearing 21 as shown in fig2 this results in an increase of the distance of the doctor 30 from the roll 1 in this maintenance position of the blade holder the doctor 30 is accessible from the side and can also be replaced by another doctor if based on the state of wear it is still possible.