Pivot Bearings or Taut Band

Pivot bearings and taut bands are specialized suspension systems used in moving coil mechanisms (such as galvanometers, precision meters, and optical scanners) to support the coil assembly while allowing precise rotational movement. Pivot bearings use jeweled or precision ball bearings at pivot points, while taut bands employ thin metal ribbons under tension to provide torsional support without sliding friction. Both systems eliminate stiction and hysteresis, enabling high-resolution angular positioning with minimal restoring torque.

These components operate by providing a low-friction rotational axis for the moving coil. In pivot bearings, the coil rotates on precision pivots within jewel or miniature ball bearings, minimizing friction through rolling contact. Taut bands use thin metal ribbons (typically beryllium copper or phosphor bronze) stretched under tension between fixed points; the coil attaches to the center of the bands, which twist elastically to allow rotation while providing a linear restoring torque proportional to angular displacement. Both systems convert electrical current in the coil into precise mechanical rotation without the backlash or wear associated with conventional bearings.