An apparatus for converting exhaust gas constituent parts of an internal combustion engine by means of at least one catalytic converter and/or particulate filter and/or particle separator as aftertreatment components and for compensating for relative movements between the internal combustion engine and the exhaust gas section and/or for relative movements of different types of the exhaust gas section by means of at least one compensating element which permits the relative movements, - the at least one catalytic converter for converting exhaust gas constituent parts and/or the at least one particulate filter and/or the at least one particle separator being arranged within the compensating element (20.1 - 20.8, 20.X, 20.Y, 20.Z) and/or within a part of the exhaust gas section which is connected non-releasably to the compensating element, - the external diameter of the catalytic converter and/or of the particulate filter and/or of the particle separator being smaller than or equal to the internal diameter of the compensating element (20.1 - 20.8, 20.X, 20.Y, 20.Z) and/or the part of the exhaust gas section which is connected non-releasably to the compensating element, characterized in that - an exhaust gas part stream (11, 11.1) branches off from the exhaust gas stream (10, 10.1) upstream of an SCR catalytic converter (6, 6.1), - a reservoir for a reducing agent and a metering device for a reducing agent are provided, and the metering device adding the reducing agent into the exhaust gas part stream (11, 11.1), - the reducing agent is a substance which breaks down into ammonia downstream of the feeding point as a result of the hot exhaust gas, or the reducing agent is ammonia, - the exhaust gas part stream (11, 11.1) is returned into the exhaust gas stream (10, 10.1) downstream of the feeding point and upstream of the SCR catalytic converter (6, 6.1), - the SCR catalytic converter (6, 6.1) which is arranged downstream of the returning point reduces the nitrogen oxides contained in the exhaust gas stream into nitrogen and water vapour with the aid of the broken-down ammonia by way of selective catalytic reduction, - an oxidation catalytic converter (16, 16.1) is arranged in the exhaust gas part stream (11, 11.1) upstream of the feeding point for the reducing agent, which oxidation catalytic converter (16, 16.1) oxidizes backflowing ammonia and/or backflowing reducing agent decomposition products in the engine operating conditions, in which there is a reversal of the exhaust gas stream into the direction of the internal combustion engine, and - the oxidation catalytic converter (16, 16.1) is arranged within the at least one compensating element (20.1, 20.3, 20.6, 20.X, 20.Y, 20.Z) and/or within a part of the exhaust gas section which is connected non-releasably to the compensating element, - the external diameter of the at least one aftertreatment component which protrudes into the compensating element being smaller than or equal to the inner diameter of the compensating element. - the at least one catalytic converter for converting exhaust gas constituent parts and/or the at least one particulate filter and/or the at least one particle separator being arranged within the compensating element (20.1 - 20.8, 20.X, 20.Y, 20.Z) and/or within a part of the exhaust gas section which is connected non-releasably to the compensating element, - the external diameter of the catalytic converter and/or of the particulate filter and/or of the particle separator being smaller than or equal to the internal diameter of the compensating element (20.1 - 20.8, 20.X, 20.Y, 20.Z) and/or the part of the exhaust gas section which is connected non-releasably to the compensating element, - an exhaust gas part stream (11, 11.1) branches off from the exhaust gas stream (10, 10.1) upstream of an SCR catalytic converter (6, 6.1), - a reservoir for a reducing agent and a metering device for a reducing agent are provided, and the metering device adding the reducing agent into the exhaust gas part stream (11, 11.1), - the reducing agent is a substance which breaks down into ammonia downstream of the feeding point as a result of the hot exhaust gas, or the reducing agent is ammonia, - the exhaust gas part stream (11, 11.1) is returned into the exhaust gas stream (10, 10.1) downstream of the feeding point and upstream of the SCR catalytic converter (6, 6.1), - the SCR catalytic converter (6, 6.1) which is arranged downstream of the returning point reduces the nitrogen oxides contained in the exhaust gas stream into nitrogen and water vapour with the aid of the broken-down ammonia by way of selective catalytic reduction, - an oxidation catalytic converter (16, 16.1) is arranged in the exhaust gas part stream (11, 11.1) upstream of the feeding point for the reducing agent, which oxidation catalytic converter (16, 16.1) oxidizes backflowing ammonia and/or backflowing reducing agent decomposition products in the engine operating conditions, in which there is a reversal of the exhaust gas stream into the direction of the internal combustion engine, and - the oxidation catalytic converter (16, 16.1) is arranged within the at least one compensating element (20.1, 20.3, 20.6, 20.X, 20.Y, 20.Z) and/or within a part of the exhaust gas section which is connected non-releasably to the compensating element, - the external diameter of the at least one aftertreatment component which protrudes into the compensating element being smaller than or equal to the inner diameter of the compensating element.