Double-Nut vs Single-Nut Ball Screws: Key Differences

Ball screw nuts are available in single-nut and double-nut types. The double-nut version offers a higher load capacity, a longer service life and greater convenience for subsequent maintenance.

Single-nut and double-nut variants share the same mounting dimensions but differ in length – the double-nut nut is twice as long as the single-nut one, and its load capacity is more than double that of the single-nut type.

A single-nut ball screw consists of a single nut assembly and may exhibit a slight axial clearance in practical applications. However, such axial clearance can be significantly reduced through stringent manufacturing control, and the nut can also be preloaded. These configurations are suitable for applications requiring precise positioning with light or normal preload.

Preload on a double-nut ball screw is applied by rotating the two nuts in opposite directions respectively, and the nuts are secured by the pins installed between them. This design completely eliminates axial clearance and increases structural rigidity through preloading. The double-nut type is suitable for machinery that requires high rigidity and precise positioning under moderate or heavy loads.

Double-nut ball screws feature a higher load capacity, excellent stability and high precision, and are thus mostly applied to the transmission systems of large-scale equipment. By contrast, single-nut ball screws are designed for light load applications, with the advantages of easy assembly and disassembly, lower cost and a compact overall nut structure. They are suitable for small-sized equipment that requires high transmission speed but has relatively low precision requirements.

A ball screw selection only needs to meet the operational requirements of the equipment.