line 36 through which parts of the exhaust gases or mixture of exhaust gases and secondary air can be directed past the turbine 32 the amount of air directed past is determined by a wastegate 38 if the wastegate 38 is closed this leads to a maximum exhaust gas flow through the turbine 32 which then leads to a maximum compression of the fresh air in the intake duct the boost pressure is increased as a result if on the other hand the wastegate 38 is opened to the maximum as many exhaust gases as possible flow through the bypass channel 36 whereupon the turbine power taken up by the turbine 32 drops in parallel with this there is a decrease in the power delivered by the compressor 16 and consequently in the boost pressure 0022 fig2 shows the actuation of the wastegate 38 in schematic form the wastegate 38 possesses a wastegate flap 40 which covers an inlet opening 42 toward that end the flap 40 is mounted about a swiveling axis 44 the varying distance between the throttle flap 40 and the opening 42 produces a reduced throughflow area in terms of flow rate with the result that a varyingly large proportion of the exhaust gases flows through the bypass line 36 the wastegate flap 40 is mechanically linked to a diaphragm box 46 the diaphragm box 46 has two mutually separate chambers 48 and 50 to which pressure is applied via the lines 52.