Abstract: An eccentric screw pump or motor which includes; stators (3) having an elastic flexible coatings (32) which forms a helical bore with teeth (37) and tooth gaps (38) and a rotor (4) disposed for rolling movement in the bore and being formed with teeth (35) and tooth gaps (36) which are engageable with the stator bore. To enhance performance over a wider range of operating temperatures, the bore defined by the elastic flexible coating is formed with a plurality of waves (4) and grooves (39) which, like the teeth (37) and tooth gaps (38) of the bore are helical, but which have dimensions in both the circumferential and radial directions that are smaller than the dimensions of the teeth (37) and tooth gaps (38) of the bore.

Abstract: An eccentric screw pump or motor which includes a stator 3 having an elastic flexible coating 32 which forms a helical bore with teeth 37 and tooth gaps 38, and a rotor 4 disposed for rolling movement in the bore and being formed with teeth 35 and tooth gaps 36 which are engageable with the stator bore. To enhance performance over a wider range of operating temperatures, the bore defined by the elastic flexible coating is formed with a plurality of waves 41 and grooves 39 which, like the teeth 37 and tooth gaps 38 of the bore are helical, but which have dimensions in both the circumferential and radial directions that are smaller than the dimensions of the teeth 37 and tooth gaps 38 of the bore.