The follower arm potentiometer is used to maintain constant tension when using a brake for unwind tension, or when using a clutch for rewind tension. The potentiometer connects to the Huco power supply and replaces the vernier potentiometer (see Huco power supply).
The lightweight follower arm rests on the roll as shown in the diagram. As the roll diameter increases or decreases, the arm moves upward or downward rotating the potentiometer’s shaft. The power supply current and thereby the torque is varied in direct proportion with the changing roll diameter to maintain constant tension.