US Patent 7108461 Clamp with magnetic spindle positioner

A clamping apparatus includes a clamp arm that is pivotable between a raised position and a lowered position, and a clamp spindle assembly that is adjustably positionable along the length of the arm. A magnet in the clamp spindle assembly magnetically engages the clamp arm with sufficient magnetic force to maintain the spindle assembly in a selected position as the clamp arm is moved between its raised and lowered positions, while allowing the position of the clamp spindle assembly to be manually adjusted.