Abstract: An impeller includes a central shaft or a tube for mounting on a shaft; around the shaft or tube a hollow hub, which in the direction from one end to the other end increases in diameter. The hub possesses an outside and an inside oriented towards the shaft or tube; a back wall which is provided at the end of the hub with the largest diameter perpendicular to the shaft or tube which at least partially closes the hollow space of the hub; a series of blades that are attached to the outside of the hub by their base; wherein a number of flat, straight reinforcing ribs are provided which extend on the shaft or tube in an essentially radial direction and form a radial connection between the shaft or tube and the inside of the hub.

Abstract: An element for compressing or expanding a gas including a rigid housing (2) containing an internal chamber; a rotor (3a, 3b) situated in the internal chamber and comprising a rotor shaft (4a, 4b); one or more bearings (7) in which the rotor shaft (4a, 4b) is bearing-supported, wherein the rotor (3a, 3b) with its rotor shaft (4a, 4b) is rotatably mounted with respect to the housing (2) by means of these bearings (7), wherein the rotor (3a, 3b) is mounted with one or more clearances with respect to a wall (5) of the internal chamber, and the element (1) is provided with a separate yielding component (10) which is positionally adjustable with respect to the housing (2) in such a way that at least one of the clearances can be acted upon, wherein the separate yielding component (10) is not directly attached to the rotor (3a, 3b).

Abstract: An element for compressing or expanding a gas including a rigid housing (2) containing an internal chamber; a rotor (3a, 3b) situated in the internal chamber and comprising a rotor shaft (4a, 4b); one or more bearings (7) in which the rotor shaft (4a, 4b) is bearing-supported, wherein the rotor (3a, 3b) with its rotor shaft (4a, 4b) is rotatably mounted with respect to the housing (2) by means of these bearings (7), wherein the rotor (3a, 3b) is mounted with one or more clearances with respect to a wall (5) of the internal chamber, and the element (1) is provided with a separate yielding component (10) which is positionally adjustable with respect to the housing (2) in such a way that at least one of the clearances can be acted upon, wherein the separate yielding component (10) is not directly attached to the rotor (3a, 3b).

Abstract: An impeller includes a central shaft or a tube for mounting on a shaft; around the shaft or tube a hollow hub, which in the direction from one end to the other end increases in diameter. The hub possesses an outside and an inside oriented towards the shaft or tube; a back wall which is provided at the end of the hub with the largest diameter perpendicular to the shaft or tube which at least partially closes the hollow space of the hub; a series of blades that are attached to the outside of the hub by their base; wherein a number of flat, straight reinforcing ribs are provided which extend on the shaft or tube in an essentially radial direction and form a radial connection between the shaft or tube and the inside of the hub.