Caps passing through the spindle capper (or spindle/snap capper) are threaded down by sets of tightening spindles.  Each set of spindles on the spindle capper will tighten the cap onto the container until the ideal torque is met.

Tightening spindles can be raised or lowered to accomodate different size containers.  Similarly, the spindle capper allows the gap between the sets of spindles to be widened or narrowed, again allowing the capping machine to handle a range of container widths.

The speed of each set of spindles is easily controlled and the final set of spindles will normally contain two spindle clutches to allow for even greater torque control!