data sheets for robolink standard arms (RL-D-RBT-xxxxx-BC-(AE)

igus supplies “electromechanical joint arms“. They consist of:

  • robolink joints with worm gears (RL-D) and strain wave gears (RL-S),
  • igus stepper motors NEMA11, -17, -23 and -23XL,
  • Ini-switches for the Zero-Point definition (BC version) or Output encoders (BC-AE version),
  • connection parts between these joints (folded metal sheets RL-DC)
  • a set of igus cables (5m long) and e-chains for the connection to a control unit
  • OPTIONAL: an adapter for the connection of an Actuator (gripper, suction cup, camera,…)

Please find attached data sheets and STEP data for the different configurations:


“small version” with 2x RL-D-30 and 2x RL-D-20 (payload max. 1 kg, reach ~600 mm)

“big version” with 2x RL-D-50 1x RL-D-30 and 1x RL-D-20 (payload max. 3 kg, reach ~750 mm)

Output Encoder for RL-D / RL-S

We supply 2 options of encoders for our joints / joint arms.

Option 1 (our Standard before HMI 2017): Motorencoder plus Ini switch for 0-point reference on the joint output (PRT bearing)

Option 2): Output encoder on the PRT bearing of the joint. This is our own development, we use a magnetic ring plus Encoderchip on the output with an aditional magnet and Hall Sensor as reference point. Please find attached a description of the output encoder attached in GER and ENGL. Advantage: less cables, higher resolution, more accuracy for the arm.

DOWNLOAD section:

output encoder DEU: RL-D Sensorik Doku (#3)

output encoder ENGL: RL-D Sensors Dok (E #3)

strain wave gear (RL-S) vs. cycloid gear (RL-C)

The strain wave gear is available as a product in the size RL-S-17 and RL-S-20. RL-S-30 is a prototype and still in development.

The cyclo gear can be an alternative in future and is not available as a product yet. The sizes 17 and 20 are currently in development.

Both types of gears contain a coaxial in- and output axis (different from RL-D worm gears), they consist of three similar components:

  • An outer (static) toothed ring
  • An inner toothed ring (rigid in the cycloid gear, flexible in the SWG)

  • A drive (an excentric in the case of the cycloid gear, the wave generator in the SWG)



strain wave gear with flexible inner ring                  cycloid gear with excentric ring



more data for download (Catalogue, STEP, drawings)

I want to supply more data for you to be downloaded, especially about our RL-DC “standard arms”. Our standard arms include all joints, motors, connections (=c-shaped metal sheets), cables and chains. Attached our NEW catalogue (now also available in ENG), STEP data for our 8 standard configurations and also the related drawings with part lists. We have “small arms” (up to 1 kg, based on our joints RL-D-30 and RL-D-20) as 4 or 5 DOF and “big arms” (up to 3 kg, based on our joints RL-D-50, -30 and -20).


Version With motorencoder and Ini switch or “output encoders” (-AE). I will explain the difference in a later entry.


NEW Catalogue 2017-04 in engl.:  EN_robolink_2017_2

STEP data small robots (4 versions): STEP Daten BC klein

DRAWINGS small robots (4 versions): Zeichnungen BC klein

STEP data big robots (4 versions): STEP Daten BC groß

DRAWINGS big robots (4 versions): Zeichnungen BC goß

RL-S strain wave gears now available

At the HMI trade show we released our strain wave gear (RL-S) as a product in addition to our worm gears (RL-D). The smallest version of the strain wave gear (RL-S-17-N11-00-28-020K0) is used for the fifth axis in the standard joint arms RL-D-RBT-5532S-XX and RL-D-RBT-3322S-XX. The RL-S-17 gear comes in two variations, both have a transmission rate of 28:1:

1. suitable for small motors (like NEMA11 stepper motors, holding torque = 0.1 Nm), output torque max. 1 Nm

2. suitable for slightly bigger motors (like NEMA17 stepper motors, holding torque = 0.5 Nm), output torque max. 3 Nm

The biggest available joint is the RL-S-20-N23-00-38-12000 with a transmission rate of 38:1. The maximum output torque is about 5 Nm, depending on speed and usage duration. Also here you are able to choose between two versions:

1. high-end: RL-S-20-N23-00-38-12030 (with PRT-01-20)

2. standard: RL-S-20-N23-00-38-12000 (with a standard PRT-02-20-AL)

attached are CAD data and the current data sheets: RL-S-STEP+Data

All gears can be purchased with igus stepper motors, initiator kits, encoder kits or customized to be combined with your motor!