The invention concerns a rotor arrangement for an electrical drive motor of a compressor, particularly a refrigerant compressor, with a rotor having a rotor lamination of stacked sheet plates, and a shaft, which is inserted in an axial recess of the rotor lamination and is unrotatably connected with the rotor lamination, the recess being formed by openings in adjacent sheet plates. In an embodiment, the order of addition of reactants affects the properties of the resultant product urethane. Further, disclosed is a acidic protein foodbeverage comprising the dispersion stabilizer. The spring groups in the side frames are relatively soft, giving a low vertical bounce natural frequency.