The type of preload is determined by the geometric arrangement of the nut components:
O Preload
With O preload, the two nut halves are pushed apart by a spacer ring or targeted rotation. The load angles form an O-shaped pattern. The spindle is under tensile stress, resulting in high axial rigidity and optimal load-bearing capacity. This preload can be precisely adjusted even after assembly—particularly with flange double nut designs.
X Preload
Here, the nut components are pressed together by external forces, e.g., via an adjustment screw in the housing. The load angles form an X-shaped pattern. The spindle is under compressive stress, while the preload is applied from outside to inside and is often controlled via a limiting ring. This variant is used in cylindrical double nut designs and provides a defined, reproducible preload force.
