A rotary lead-through assembly supplies an operating fluid to a rotor of a
machine for processing printing material. An operating cylinder includes
an expansion chamber and a piston having a piston outlet opening. The
piston is mounted so as to be displaceable towards the rotor for coupling
a rotor inlet opening and the piston outlet opening with one another. A
pressure generator is connected both to the expansion chamber and to the
rotor, when the openings are coupled with one another. A threshold value
valve is disposed between the expansion chamber and the piston outlet
opening. The valve is automatically openable when a given threshold value
of an excess pressure of the operating fluid is exceeded. A machine for
processing printing material is also provided.
