Whorl Diameter and Speed Ratio
topic
The whorl is the pulley on the spindle shaft that contacts the tangential belt. Spindle speed = motor whorl diameter / spindle whorl diameter × motor speed. Whorl diameters range from 18–25 mm; changing the whorl is the primary mechanical method for changing spindle speed. Whorl surface must be precision-ground for concentricity (±0.01 mm) to avoid cyclic speed variation. Taper-fit whorls enable quick removal for cleaning and inspection.
Role
Whorl selection for speed change is the first practical skill required when setting up a ring frame for a new yarn count. Understanding the speed ratio calculation prevents the common error of producing yarn at incorrect twist levels due to wrong whorl installation — an error that can affect an entire machine's output before detection.