Abstract: A rotary rheometer has two measurement parts which delimit a measurement gap and can be moved relative to one another in a predetermined movement direction by an adjustment device. At least one switching unit is provided, which responds to changes in a force flow in a force circuit of the rotary rheometer delimited by the measurement parts and has switching contacts for the activation of an adjustment device, which stops the adjustment device when a predetermined limit force value is exceeded for the force flow in the positive or negative direction, optionally without relative movement of the measurement parts, or with the measurement parts remaining in the same position.