A preloaded nut is a ball screw nut or trapezoidal nut in which the axial play between the screw and the nut is eliminated by applying a specific preload. This reduction results in greater rigidity, precision and load-bearing capacity without causing deformation of the nut or screw.
The preload on the nut ensures that:
- Minimises backlash
- Positioning accuracy is improved during changes of direction
- Improve power transmission and the rigidity of the screw drive
- The load is distributed more evenly across the balls, which extends their service life
Technical specifications
- Ball sorting
Balls of varying sizes are specifically incorporated to generate a defined preload - Double nut arrangement
Two nuts are rotated against each other and fixed with screws to eliminate backlash. - Adjustable preload
The preload force is adjusted via adjustment screws or axial spacer rings. Preload is usually specified as a percentage of the nut’s dynamic load rating (typically 1–10%)
Practical relevance
- This is particularly important in high-precision CNC machines, robotics or measurement systems, where high repeatability is required
- Reduces vibrations, play and misalignment
- Extends service life by ensuring an even distribution of load across the balls