Abstract: A sealing arrangement between the shaft and housing of a fluid flow engine with a blocking gas space limited by piston rings; the blocking gas pressure is controlled by changing the effective cross section of venting bores and therewith is matched to the gas pressure to be sealed off; the change of the cross section of the venting bores is thereby automatically realized by axial displacement of the corresponding piston ring as a function of the gas, respectively, blocking gas pressure acting on the same. An axial wear at the piston ring and at the groove flank, which is present during the running-in period, is avoided subsequent thereto as a result of the decrease of the blocking gas pressure.