Abstract: A viscometer has a hollow cylinder mounted in a base frame and rotated about its longitudinal axis. A measuring part being flowed through by a fluid to be tested is rotatably supported in the hollow cylinder. An electromagnetic drive with a stator and a rotor for the hollow cylinder is provided, with which the hollow cylinder is rotatable. The stator is supported on the base frame and the rotor is supported on the hollow cylinder. An electromagnetic coupling of the stator with the rotor is provided by a ring rotor disposed between the stator and the rotor. The ring rotor is mounted about the longitudinal axis of the hollow cylinder so that the base frame and the hollow cylinder are decoupled with respect to the electromagnetic drive and a torque by the electromagnetic drive is applied to the hollow cylinder while the acting forces on the hollow cylinder are minimized.

Abstract: A viscometer has a hollow cylinder mounted in a base frame and rotated about its longitudinal axis. A measuring part being flowed through by a fluid to be tested is rotatably supported in the hollow cylinder. An electromagnetic drive with a stator and a rotor for the hollow cylinder is provided, with which the hollow cylinder is rotatable. The stator is supported on the base frame and the rotor is supported on the hollow cylinder. An electromagnetic coupling of the stator with the rotor is provided by a ring rotor disposed between the stator and the rotor. The ring rotor is mounted about the longitudinal axis of the hollow cylinder so that the base frame and the hollow cylinder are decoupled with respect to the electromagnetic drive and a torque by the electromagnetic drive is applied to the hollow cylinder while the acting forces on the hollow cylinder are minimized.