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RBE Series Frameless Motors

The RBE Series is a proven direct-drive platform, with many years of application success in defense, semiconductor, machine tools, industrial automation, medical, robotics and other industries. The frameless configuration is supplied as a rotor and stator component that can be integrated directly into the machine, using the same bearings to support both the load and the motor. This design eliminates shaft, bearings, endbells, and couplings to reduce volume, weight and complexity.

Limited availability outside North America



  • 10 frame sizes from 21.3mm to 239mm OD
  • Continuous torque range from .01 N-m to 38 N-m
  • Peak torque range from .03 N-m to 200 N-m
  • Speeds up to 35,000 rpm
  • Standard and custom windings to match speed/torque performance requirements
  • RBEH housed models come with stainless steel shafts and can include any combination of Hall sensors, encoder or resolver as rotor position feedback devices
  • RBE frameless models use the load’s own shaft and bearings, and can include integral Hall sensors, and additional position feedback devices such as encoders or resolvers can be added as separate components


  • Low cogging for smooth low-speed rotation
  • Brushless design allows significant reductions in rotor inertia and increases in acceleration
  • Improved cooling and efficiency provides increased performance in a wide variety of operating conditions
  • Frameless configuration reduces machine size and maintenance requirements since load and motor use same set of bearings

Get Started

Count on Kollmorgen support to help you design and build a successful machine and keep it reliably productive, anywhere in the world. Our co-engineering experts will work with you to tailor a perfect-fit solution for your motion requirements.

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Technology Brief
Title Language(s) Date Size
Kollmorgen RBE Servostar technical publication English 26 Feb 2018 335.02 KB Copy URL
Title Language(s) Date Size
Motors with Servostar S Catalog EN 2003 English 12 Sep 2013 334.27 KB Copy URL
Title Language(s) Date Size
RBE Series Motors Brochure EN 2003 English 12 Sep 2013 503.84 KB Copy URL
Ingress Protection of Servo Motors [toc] Sealing is an important design tool used to prolong the life of motors against harsh environments containing dust or liquid contaminants. There are arguably an unlimited number of...
Normen und Richtlinien [toc] Allgemeines Struktur des Normenwesens am Beispiel der EN ISO 12100 Europäische Richtlinien New Legislative Framework Blue Guide: Leitfaden für die Umsetzung der...
Frameless Motor Mounting Practices: Clamping and Bolting Embedded Motion Technology - Frameless  Mounting Considerations The benefits of Improved System Performance, Reduced Maintenance, Smaller Mechanical Footprint, Higher System...
Frameless Motor Mounting Practices: Bonding with Structural Adhesives Embedded Motion Technology - Frameless  Mounting Considerations The benefits of Improved System Performance, Reduced Maintenance, Smaller Mechanical Footprint, Higher System Efficiency...
Standards and Directives [toc] General Structures of standards with EN ISO 12100 as an example ISO Standards Safety of Machinery — General Principles for Design ISO 12100:2010 UL Standards...


Title Language(s) Date Size
Blue Guide German 15 Jul 2015 Copy URL
pdfCEL China Efficiency Labelling for Servo and Stepper Motors English 17 Dec 2021 139.72 KB Copy URL
pdfKollmorgen CE Technical Notice - Servo and Stepper Motors Efficiency English 26 Aug 2020 389.92 KB Copy URL