Abstract: A flow control has a rotary gate residing within an internal flow space in a conduit. The gate is mounted for movement relative to the conduit between first and second positions, the gate in the first and second positions accounting for a different flow rate between first and second fluid masses between which the gate resides. The gate has an actuator with a plurality of spaced shoulders. A flexible force-applying member is connected to the actuator and bears upon the shoulders to thereby urge the gate towards the other of the first and second positions. The shoulders are situated so that the number of shoulders engaged by the force-applying member at any one time is not the same as the gate moves from the one of the first and second positions towards the other of the first and second positions.