Roller Screw Basics

Exlar’s patented, inverted roller screw is a mechanism for converting rotary torque into linear
motion, in a similar manner to acme screws or ball screws. But, unlike those devices, roller
screws can carry heavy loads for thousands of hours in the most arduous conditions. This
makes roller screws the ideal choice for demanding, continuous-duty linear motion applications.

The difference is in the roller screw’s design for transmitting forces. Multiple threaded helical
rollers are assembled in a planetary arrangement around a threaded shaft as seen below,
which converts a motor’s rotary motion into linear movement of the shaft or nut.


Compare a similar size ballscrew to Exlar’s planetaryroller screw design and see many more contact points on the roller screw. This results in up to 15 times the load-carrying capacity of
ball screws and improved stiffness.