Lead Screw Linear Actuators - External Nut - LE Series

External-nut lead screw actuators are motorized lead screw assemblies that convert rotary motion into controlled linear travel. The lead screw is integrated with the stepper motor shaft, while the drive nut remains outside the motor body. As the motor rotates the screw, the nut must be restrained from turning by the attached load or an external guide, forcing it to move axially in a straight line. The moving component can mount directly to the nut, making this design a compact and adaptable solution for positioning, adjustment, dispensing, automation, and other controlled-motion applications.

Screw lead determines how far the nut travels with each motor revolution. Finer leads generally provide greater mechanical advantage, thrust, and positioning resolution, while larger leads provide faster linear travel per revolution. The motor, screw diameter, lead, and nut design work together to determine the actuator’s speed, force, accuracy, and available travel. Because the external nut and attached load require support and anti-rotation, these actuators are normally used with a separate linear guide, rail-supported shaft, or other guidance system.

PBC Linear® LE Series external-nut lead screw actuators integrate the screw directly into NEMA 08, 11, 14, 17, or 23 stepper motors. Metric and imperial screw options, multiple leads, several motor body lengths, and different nut configurations allow designers to match the actuator to available space and motion requirements. Standard nuts support general positioning applications, while anti-backlash nuts reduce axial play for improved positioning accuracy and repeatability.

The LE Series is available with external round nuts that provide a convenient connection point for the moving load. Product configurations include compact NEMA 11 and NEMA 14 actuators for space-limited equipment, NEMA 17 options for general automation, and larger NEMA 23 models for applications requiring more motor torque. Available actuator lengths, screw diameters, and leads provide options ranging from short, fine-lead positioning assemblies to longer actuators designed for faster linear travel.

Features and benefits

• Lead screw is integrated directly with the motor shaft
• Motor rotates the screw, forcing the restrained nut to travel axially in a straight line
• External nut provides a direct mounting point for the moving component
• Standard and anti-backlash nut options
• Metric and imperial lead screw options
• Multiple screw diameters and leads for different speed, thrust, and resolution requirements
• Finer leads favor thrust and positioning resolution
• Larger leads provide faster linear travel per revolution
• NEMA 08, 11, 14, 17, and 23 motor frame sizes
• Multiple motor body lengths for different torque and space requirements
• External guidance supports the load and prevents nut rotation
• RoHS compliant
• Class B insulation
• Operating temperature range: 0°C to +50°C
• Step accuracy: ±5%

Frequently Asked Questions