Integrated robot joint actuator
HighTorque HTDW servo joint modules integrated robot joint actuator
Compact geared joint modules with dual absolute encoders in 44 to 75 mm square housings, from 2 Nm rated (HTDW-4438, 30:1) to 10 Nm rated (HTDW-6036, 36:1) and up to 60 Nm locked-rotor torque (HTDW-7535).
Key specifications
| Rated torque | 2–10 Nm |
|---|---|
| Peak torque (max) | 60 Nm |
| Feedback | dual absolute encoders |
| Ratio | 22–36:1 |
| Weight | 850 g |
Summarised in our own words from High Torque Technology Co., Ltd.'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Peak value is the published locked-rotor torque. Voltage and bus not stated per module; HighTorque's control box uses CAN/FDCAN at 5 Mbps.
Specify Motion is not affiliated with High Torque Technology Co., Ltd.. HighTorque and HTDW servo joint modules 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 a HighTorque 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 | HTDW servo joint modules | MAH |
|---|---|---|
| Peak torque | 60 Nm | 800 Nm meets or exceeds |
| Rated torque | 10 Nm | 557 Nm meets or exceeds |
| Speed | — | 125 rpm |
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 | HTDW servo joint modules | MAT |
|---|---|---|
| Peak torque | 60 Nm | 800 Nm meets or exceeds |
| Rated torque | 10 Nm | 557 Nm meets or exceeds |
| Speed | — | 102 rpm |
Harmonic actuator with an integrated German-made Synapticon Circulo servo drive on EtherCAT, with STO and optional FSoE functional safety.
| Published maximum | HTDW servo joint modules | MGM |
|---|---|---|
| Peak torque | 60 Nm | 459 Nm meets or exceeds |
| Rated torque | 10 Nm | 267 Nm meets or exceeds |
| Speed | — | 108 rpm |
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 HighTorque HTDW servo joint modules
Send these with your enquiry and an engineer can confirm the right HTDW servo joint modules 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
HighTorque HTDW servo joint modules: frequently asked questions
What is the HighTorque HTDW servo joint modules?
Compact geared joint modules with dual absolute encoders in 44 to 75 mm square housings, from 2 Nm rated (HTDW-4438, 30:1) to 10 Nm rated (HTDW-6036, 36:1) and up to 60 Nm locked-rotor torque (HTDW-7535). Published series figures include rated torque 2 Nm, rated torque 10 Nm, peak torque 60 Nm, ratio 22:1. It is made by High Torque Technology Co., Ltd.; Specify Motion can help source it or propose an equivalent.
Who makes the HighTorque HTDW servo joint modules?
The HighTorque HTDW servo joint modules is made by HighTorque (High Torque Technology Co., Ltd.) and is listed here for engineers comparing options. Specify Motion is not affiliated with High Torque Technology Co., Ltd.; brand names are used only to identify the product.
What is the rated torque of the HighTorque HTDW servo joint modules?
The published series minimum rated torque is 2 Nm. Individual models and sizes in the HTDW servo joint modules 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 HighTorque HTDW servo joint modules?
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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