off of the wharve 12 of the opener roller 11 the opener roller 11 is braked quickly and securely and is brought to a stop when the cover 7 is being closed the deflection lever 4 swivels back into the starting position shown in fig1 so that the drive belt 6 is again brought into contact with the drive disk 2 the rotation of the drive disk 2 is transmitted via drive belt 2 to the wharve 12 of the opener roller 11 which is thereby caused to rotate again the stop 43 ensures that the deflection lever 4 always swivels around axis 42 when the actuating lever 51 moves in the opposite direction arrow a in such manner that the braking bolt 41 is lifted up when the machine operator or the maintenance personnel opens the cover 7 the opener roller is stopped automatically so that no danger exists from a still rotating opener roller after opening of the cover the opener roller cannot only be inspected but can also be replaced for this it is necessary to take the drive belt off the wharve of the opener roller this is done especially easily and safely with the opener device according to fig1 and 2 because when the cover is open the drive belt 6 can easily be relaxed by hand by the maintenance person for this purpose the actuating lever 51 is provided with a handle 52 upon grasping the handle 52 the maintenance person can pull the actuating lever 51 in the direction of the arrow a until the right end of the oblong opening 53 presses against.