Spindle Bolster and Bearing Design
topic
The spindle bolster is the housing containing the lower spindle bearing, filled with oil for lubrication and damping. Bolster oil viscosity (SAE 5–10) determines damping characteristics; low viscosity reduces friction and power but decreases damping, allowing vibration at high speeds. Ball bearings in the upper spindle support radial loads from the balloon; the lower bolster bearing handles both radial and axial loads from the cop weight. Bearing life is 15,000–30,000 hours with correct lubrication.
Role
Bolster condition is the primary determinant of spindle noise and vibration, which are the key diagnostics for predicting spindle failure and yarn quality degradation. A spindle running on worn bearings generates periodic vibration that causes yarn count variation detectable only on the Uster Tester — a subtle but commercially significant defect. Systematic bolster inspection is the backbone of spindle maintenance.