Abstract: A rotor assembly for an electronic machine such as a motor includes a rotor on a shaft having a bearing at each end portion, the bearings being arranged to rotatably support the rotor and shaft. The assembly further includes a balancing member, from which material may be removed for balancing the rotor assembly. The balancing member is located in a predetermined position and orientation with respect to the rotor. The balancing member includes an encoder disk, arranged to permit positioning of the rotor with respect to a stator. The provision of a balancing member having an integral encoder disk facilitates the manufacture of the rotor assembly. As the balancing member is located in a predetermined position, the encoder automatically assumes a predetermined position and hence the position of the rotor can be determined with certainty.

Abstract: A rotor assembly that includes a shaft to which are mounted an impeller, a rotor core and a bearing cartridge. The bearing cartridge is mounted between the impeller and the rotor core and comprises a pair of bearings, a spring that applies a preload to each of the bearings, and a sleeve that surrounds the bearings.

Abstract: A centrifugal compressor that includes an impeller, a diffuser and a shroud. One of the diffuser and shroud includes a plurality of recesses and the other of the diffuser and shroud includes a plurality of radial vanes. The shroud covers the impeller and diffuser such that each radial vane projects into a respective recess.