Frameless torque motor
Allient MegaFlux frameless torque motors
Frameless direct-drive brushless torque motors in 12 diameters from 60 to 330 mm, continuous stall torque up to 181 Nm, 48–300 V DC bus and clear apertures up to 582 mm.
Key specifications
| Voltage (max) | 300 V |
|---|---|
| Outer diameter | 60–330 mm |
| Inner diameter (max) | 230 mm |
| Continuous torque (max) | 181 Nm |
| Rated speed | 330–4,000 |
Summarised in our own words from Allient Inc.'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Peak torque not on the product page. Page also cites clear ID aperture up to 582 mm.
Specify Motion is not affiliated with Allient Inc.. Allient and MegaFlux frameless torque motors 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 Allient 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.
High-voltage (600 VDC) frameless torque motor kits from 110 to 360 mm with large through-bores and integrated Hall sensors; the high-torque end of the Akribis frameless range.
| Published maximum | MegaFlux frameless torque motors | ADR-P |
|---|---|---|
| Continuous torque | 181 Nm | 365 Nm meets or exceeds |
| Peak torque | — | 985.5 Nm |
Housed iron-core direct drive rotary motors with bearings and optical encoder, 110-360 mm frames, up to about 1 kNm peak at 600 VDC.
| Published maximum | MegaFlux frameless torque motors | ADR-A |
|---|---|---|
| Continuous torque | 181 Nm | 407.2 Nm meets or exceeds |
| Peak torque | — | 1,017.9 Nm |
| Speed | — | 2,000 rpm |
Low-profile housed iron-core direct drive motors with large centre holes and incremental encoders, 80-400 mm frames.
| Published maximum | MegaFlux frameless torque motors | AXD |
|---|---|---|
| Continuous torque | 181 Nm | 250.6 Nm meets or exceeds |
| Peak torque | — | 648.9 Nm |
| Speed | — | 3,000 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 a frameless torque motor is
A frameless torque motor is a permanent-magnet brushless motor supplied as two parts, a rotor and a stator, with no housing, bearings or shaft. The machine builder mounts the rotor directly on the driven shaft and the stator in the machine structure, so the motor becomes part of the mechanism. Many have large through-holes and high pole counts, giving high torque at low speed with no gearbox. They need separate feedback, typically an encoder, and a servo drive.
When engineers choose a frameless torque motor
Choose a frameless motor when you want direct drive in a compact, integrated design, such as robot joints, gimbals, rotary tables and medical devices. Removing the gearbox eliminates backlash and improves stiffness and smoothness. The trade-offs are integration work and size: the builder supplies bearings, alignment, cooling and feedback, and torque per volume is lower than a geared solution. For off-the-shelf installation, a housed direct-drive motor may be simpler.
How to specify the Allient MegaFlux frameless torque motors
Send these with your enquiry and an engineer can confirm the right MegaFlux frameless torque motors variant or an equivalent:
- Continuous and peak torque (Nm)
- Speed (rpm)
- Outer diameter, bore and stack length (mm)
- Bus voltage and current (V, A)
- Thermal mounting and cooling
- Feedback type and resolution
- Air gap and concentricity tolerance (mm)
Common mistakes to avoid
- Leaving air gap and concentricity tolerances undefined
- Ignoring heat conduction from the stator into the housing
- Using an encoder with too low resolution for direct drive
- Forgetting rotor magnet attraction during assembly
Allient MegaFlux frameless torque motors: frequently asked questions
What is the Allient MegaFlux frameless torque motors?
Frameless direct-drive brushless torque motors in 12 diameters from 60 to 330 mm, continuous stall torque up to 181 Nm, 48–300 V DC bus and clear apertures up to 582 mm. Published series figures include voltage 300 V, outer diameter 60 mm, outer diameter 330 mm, inner diameter 230 mm. It is made by Allient Inc.; Specify Motion can help source it or propose an equivalent.
Who makes the Allient MegaFlux frameless torque motors?
The Allient MegaFlux frameless torque motors is made by Allient (Allient Inc.) and is listed here for engineers comparing options. Specify Motion is not affiliated with Allient Inc.; brand names are used only to identify the product.
What is the voltage of the Allient MegaFlux frameless torque motors?
The published series maximum voltage is 300 V. Individual models and sizes in the MegaFlux frameless torque motors 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 Allient MegaFlux frameless torque motors?
Yes. On published figures, Akribis Systems ADR-P and Akribis Systems ADR-A are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
What is the difference between a frameless and a housed torque motor?
A frameless motor is only a rotor and stator; the machine provides bearings, shaft, housing and feedback. A housed direct-drive motor adds bearings, housing and encoder in a ready-to-install unit. Frameless suits compact, integrated designs where the machine already has stiff bearings; housed suits faster installation and simpler alignment.
Why use a frameless motor instead of a gearbox?
Direct drive removes backlash, wear and compliance in the gear train, giving smoother motion and stiffer control. It also allows a large hollow shaft for cabling. The trade-off is that torque must come from the motor alone, so it is larger for a given torque.
Further reading: How to select a frameless torque motor · Frameless motor sizing robot joints · Frameless and torque motors
Other frameless torque motor series
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