Roller screws are often considered to be best suited for applications where they replace hydraulic cylinders or other high-load drive mechanisms. Do you know what are the types of roller screw? Here, we’ll look at four roller screw designs.

The planetary roller screw design uses five primary components – a screw, a nut, satellite rollers, synchronizing gears, and guide rings. The guide rings and synchronizing gears are located at each end of the nut, and the ends of each roller have cylindrical pivots and gear teeth.

In the inverted roller screw design, the synchronizing gear is cut directly into the shaft, which allows the nut to have a smaller outer diameter than the nut of a planetary assembly with the same size screw shaft. And the inverted design typically has three starts, whereas a standard planetary roller screw typically has five or six starts. With fewer starts, the inverted design can use a larger thread form and, in turn, provide higher load capacity than a standard planetary design.

Recirculating roller screws are designed specifically for small, precise movements with high rigidity and for applications where the available motor torque is limited. The core components of a recirculating roller screw are the same as those used in the planetary roller screw.  But the rollers in a recirculating roller screw have circular grooves (no helix angle), rather than the threads found on traditional rollers.

Differential roller screws are so named because they operate based on differential movements between the internal components.  This differential makes it possible to have an extremely small lead, or linear travel distance, for each revolution of the screw.  How small?  Differential roller screws can have leads as small as 0.03 mm.  And when used with a linear scale, they can precisely move in increments smaller than 0.001 mm.