Rotary piston pump for gaseous media - having an axially and radially mounted power part (11, 12) which is configured as a spur tooth ball segment and is connected to a drive apparatus (1, 2, 3), - having a shut-off part (13, 14) which is of identical radial seal diameter, is likewise configured as a spur tooth ball segment and is driven by the power part, - having working spaces between the parts, which working spaces are formed by way of meshing of the teeth of the power part (11, 12) and those of the shut-off part (13, 14), - the power part (11, 12) and the shut-off part (13, 14) being guided in a radially sealing manner in a pump housing (5, 6) and having a respectively different number of teeth on their end sides which interact with one another, in particular, in order to achieve a pumping action or in order to generate a low pressure, - having a linear positively locking connection, delimiting the working space, between flanks and tooth meshing of the interacting teeth which lie opposite one another, - the teeth of one of the interacting parts, the power part (11, 12) or the shut-off part (13, 14), having a cycloidal development of its running face as a cycloid part, - the teeth of the other part which interacts in a meshing manner in each case with the cycloid part having corresponding tooth meshing, the radius of which can be configured freely and which runs along the flanks of the cycloid part, and - the said pump (9, 10) which is formed from a power part (11, 12) and a shut-off part (13, 14) being present in each case in a double configuration, the said pumps (9, 10) being driven jointly and it being possible for their working spaces to be connected to one another, the power parts (11, 12) which are present in a double configuration being arranged coaxially on the drive side, characterized - in that a first power part is driven by an electric motor (2, 3) which is likewise arranged coaxially in a motor housing on the drive side, and - in that the second power part is rotated jointly by the first power part in a rotationally locking manner, and - elastic means which load the power parts (11, 12) in the direction of shut-off elements (13, 14) are arranged between the said power parts (11, 12), and in that, in particular, a helical spring which is arranged coaxially with the power parts (11, 12) serves as elastic means, and - a plug-in coupling which permits an axial relative movement of the parts (11, 12) serves to produce a rotationally locked connection between the power parts. - having an axially and radially mounted power part (11, 12) which is configured as a spur tooth ball segment and is connected to a drive apparatus (1, 2, 3), - having a shut-off part (13, 14) which is of identical radial seal diameter, is likewise configured as a spur tooth ball segment and is driven by the power part, - having working spaces between the parts, which working spaces are formed by way of meshing of the teeth of the power part (11, 12) and those of the shut-off part (13, 14), - the power part (11, 12) and the shut-off part (13, 14) being guided in a radially sealing manner in a pump housing (5, 6) and having a respectively different number of teeth on their end sides which interact with one another, in particular, in order to achieve a pumping action or in order to generate a low pressure, - having a linear positively locking connection, delimiting the working space, between flanks and tooth meshing of the interacting teeth which lie opposite one another, - the teeth of one of the interacting parts, the power part (11, 12) or the shut-off part (13, 14), having a cycloidal development of its running face as a cycloid part, - the teeth of the other part which interacts in a meshing manner in each case with the cycloid part having corresponding tooth meshing, the radius of which can be configured freely and which runs along the flanks of the cycloid part, and - the said pump (9, 10) which is formed from a power part (11, 12) and a shut-off part (13, 14) being present in each case in a double configuration, the said pumps (9, 10) being driven jointly and it being possible for their working spaces to be connected to one another, the power parts (11, 12) which are present in a double configuration being arranged coaxially on the drive side, characterized - in that a first power part is driven by an electric motor (2, 3) which is likewise arranged coaxially in a motor housing on the drive side, and - in that the second power part is rotated jointly by the first power part in a rotationally locking manner, and - elastic means which load the power parts (11, 12) in the direction of shut-off elements (13, 14) are arranged between the said power parts (11, 12), and in that, in particular, a helical spring which is arranged coaxially with the power parts (11, 12) serves as elastic means, and - a plug-in coupling which permits an axial relative movement of the parts (11, 12) serves to produce a rotationally locked connection between the power parts.