Inverted Roller Screws (IRS)
High Load Capacity. Long Service Life. Precision Motion.
The Inverted Roller Screw (IRS) is the exact inverse of the standard roller screw (SRS): the nut rotates while the screw shaft translates linearly. Because the rollers do not travel axially along the shaft and the stroke occurs within a larger nut, this configuration supports higher load capacity with smaller leads, which in turn reduces driving torque. The result is a compact, efficient design that also allows the shaft to be guided directly, simplifying the surrounding structure.
The IRS is available across a wide diameter range with multiple lead options, and the nut can be customized to fit specific application requirements.
This design is an excellent option when the goal is a very compact actuator built around a rotating nut.
Description of the IRS, the Inverted Roller Screw
The IRS reverses the standard roller screw arrangement so that the nut becomes the rotating member and the screw shaft becomes the translating member. This is particularly useful in actuator designs where the shaft itself needs to remain non-rotating, whether to drive a load directly, interface with a guided carriage, or simplify anti-rotation features elsewhere in the assembly.
Because the design reduces driving torque relative to lead, the IRS is well suited to compact actuators that still require high positioning accuracy and strong load capacity.
Performance
By inverting the standard roller screw architecture, the IRS trades axial roller travel for rotational nut motion, allowing smaller leads to achieve higher load capacity while reducing the torque required to drive the system. This combination makes the IRS particularly effective in space-constrained actuator designs where compactness and direct shaft guidance matter as much as load performance.
Applications
The IRS Inverted Roller Screw is specified for compact actuator designs and applications where a rotating nut and a non-rotating, guided shaft are advantageous, including:
✦ Compact linear actuators
✦ Robotics and automation
✦ Medical and surgical devices
✦ Aerospace and defense actuation
✦ Precision positioning systems
✦ Test and measurement equipment
Engineered for Your System
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