Twist Propagation and Twist Stoppers
topic
Twist propagates from the traveller up through the balloon to the spinning triangle. Twist stoppers (thread guides, lappets, or false-twist devices) limit how far twist runs back into the drafting zone — a phenomenon called twist running back that can cause false drafting. In compact spinning, the suction zone also acts as a twist stopper. Twist propagation speed is approximately proportional to yarn torsional rigidity and inversely proportional to yarn tension.
Role
Understanding twist propagation is critical for diagnosing irregular twist distribution along the yarn, which appears as periodic strength variation and fabric barre. It is also the theoretical basis for designing false-twist devices that temporarily increase twist in the balloon to reduce breakages at high spindle speeds.