Abstract: Apparatus for controlling the tension of travelling filamentary material such as that being unwound from a drum or spool. It comprises a three phase induction motor for turning the drum or spool modified to have a high resistance rotor providing a torque speed characteristic of falling torque with increasing speed. The motor drive, and torque in either forward or reverse drive, is controlled by a pair of thyristor banks selectively triggered for forward and reverse drive modes by error signals representative of variation in tension from the required value.