Integrated robot joint actuator
igus ReBeL gearbox (robolink) integrated robot joint actuator
Integrated robot joint combining a brushless external-rotor motor, plastic strain wave gear, output encoder and CAN-bus driver board, in 80 and 105 mm sizes; up to 20 Nm maximum and 15 Nm nominal output torque at 10 rpm.
Key specifications
| Outer diameter (max) | 105 mm |
|---|---|
| Data / bus | CAN bus; igus Robot Control for up to 16 drives |
| Rated torque (max) | 15 Nm |
| Peak torque (max) | 20 Nm |
| Speed (max) | 10 rpm |
| Ratio | 50–70:1 |
| Weight | 900 g |
| Sizes | size 80: 2.5 Nm max / 2 Nm nominal, 50:1, 330 g, size 105: 20 Nm max / 15 Nm nominal, 70:1, 900 g |
Summarised in our own words from igus SE & Co. KG's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1 · Source 2
Notes on this data
Weight figure is for size 105. Used in the ReBeL cobot (2 kg payload, 664 mm reach for 6 DOF).
Specify Motion is not affiliated with igus SE & Co. KG. igus and ReBeL gearbox (robolink) are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with an igus part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These 3 series from our supply network are the closest match on published figures.
Hollow-shaft harmonic servo actuator: strain-wave gearing, motor, encoder and brake in one unit, run from a separate servo drive. Six frame sizes, from 48 VDC to 220 VAC.
| Published maximum | ReBeL gearbox (robolink) | MAH |
|---|---|---|
| Peak torque | 20 Nm | 800 Nm meets or exceeds |
| Rated torque | 15 Nm | 557 Nm meets or exceeds |
| Speed | 10 rpm | 125 rpm meets or exceeds |
Large-bore version of the harmonic actuator with a frameless 16-pole motor, giving a much bigger through-hole for cabling. Two sizes.
| Published maximum | ReBeL gearbox (robolink) | MAT |
|---|---|---|
| Peak torque | 20 Nm | 800 Nm meets or exceeds |
| Rated torque | 15 Nm | 557 Nm meets or exceeds |
| Speed | 10 rpm | 102 rpm meets or exceeds |
Harmonic actuator with an integrated German-made Synapticon Circulo servo drive on EtherCAT, with STO and optional FSoE functional safety.
| Published maximum | ReBeL gearbox (robolink) | MGM |
|---|---|---|
| Peak torque | 20 Nm | 459 Nm meets or exceeds |
| Rated torque | 15 Nm | 267 Nm meets or exceeds |
| Speed | 10 rpm | 108 rpm meets or exceeds |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What an integrated robot joint actuator is
An integrated robot joint actuator packages a brushless motor, a reduction gear, encoders, a servo drive and often a brake or torque sensor into one module that bolts in as a robot joint. Gearing may be planetary, strain-wave or cycloidal. Many are designed for legged robots, humanoids and cobots, with low gear ratios or quasi-direct drive to keep the joint back-drivable and responsive. Communication is typically over CAN or EtherCAT, with position, velocity and torque control modes.
When engineers choose an integrated robot joint actuator
Choose an integrated joint actuator to build robots faster with fewer parts, especially legged, humanoid, exoskeleton and collaborative robots. Back-drivable versions suit force control and impacts. The trade-offs are torque density, precision and industrial qualification: low-ratio designs trade output torque for transparency, and some units are aimed at research rather than production duty. For industrial arms with heavy duty cycles, a dedicated harmonic actuator or motor and gear set may be better.
How to specify the igus ReBeL gearbox (robolink)
Send these with your enquiry and an engineer can confirm the right ReBeL gearbox (robolink) variant or an equivalent:
- Peak and continuous output torque (Nm)
- Output speed (rpm)
- Gear type and ratio
- Back-drivability and torque sensing
- Supply voltage (V DC)
- Communication interface and control modes
- Mass and size (kg, mm)
Common mistakes to avoid
- Using peak torque as continuous torque
- Ignoring thermal limits in legged robots
- Overlooking bus bandwidth with many joints
- Assuming research-grade units meet industrial life requirements
igus ReBeL gearbox (robolink): frequently asked questions
What is the igus ReBeL gearbox (robolink)?
Integrated robot joint combining a brushless external-rotor motor, plastic strain wave gear, output encoder and CAN-bus driver board, in 80 and 105 mm sizes; up to 20 Nm maximum and 15 Nm nominal output torque at 10 rpm. Published series figures include outer diameter 105 mm, rated torque 15 Nm, peak torque 20 Nm, speed 10 rpm. It is made by igus SE & Co. KG; Specify Motion can help source it or propose an equivalent.
Who makes the igus ReBeL gearbox (robolink)?
The igus ReBeL gearbox (robolink) is made by igus (igus SE & Co. KG) and is listed here for engineers comparing options. Specify Motion is not affiliated with igus SE & Co. KG; brand names are used only to identify the product.
What is the outer diameter of the igus ReBeL gearbox (robolink)?
The published series maximum outer diameter is 105 mm. Individual models and sizes in the ReBeL gearbox (robolink) range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the igus ReBeL gearbox (robolink)?
Yes. On published figures, MAH and MAT are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
What is a quasi-direct-drive actuator?
A quasi-direct-drive actuator uses a high-torque motor with a low gear ratio, typically below about 10:1, so the joint is back-drivable and responds quickly to external forces. This suits legged robots and force control. The trade-off is lower output torque than high-ratio joints of similar size.
Why integrate the drive in a robot joint actuator?
Integrating the drive reduces cabling and lets each joint communicate over a shared bus, which simplifies robot design. It also allows the drive to sit close to the motor, improving control. The trade-off is that heat from both motor and drive must be managed inside the joint.
Further reading: How to select a harmonic actuator · Frameless motor sizing robot joints · Gearboxes and harmonic drives
Other integrated robot joint actuator series
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