Frameless torque motor
WITTENSTEIN alpha cyber torque motor
Direct-drive torque motors for gearless rotary axes, built in a wide span of diameters.
Key specifications
| Outer diameter | 50–540 mm |
|---|---|
| Peak torque (max) | 1,700 Nm |
Summarised in our own words from WITTENSTEIN SE's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1
Notes on this data
Grid gives max torque 0.02-1,700 Nm and size 50-540 mm only. Whether housed or frameless not stated in grid - type 'frameless' assumed from kit-style listing; verify. Related cyber kit motor (0.02-500 Nm, 19-270 mm) and cyber kit line small/medium/large (to 9,000 Nm) also listed.
Specify Motion is not affiliated with WITTENSTEIN SE. WITTENSTEIN alpha and cyber torque motor 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 WITTENSTEIN alpha part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These series from our supply network is the closest match on published figures.
In-runner frameless torque motors from 65 to 410 mm stator OD with 8-64 poles, low profile and large through-holes; windings tailored to target speed.
View series →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 WITTENSTEIN alpha cyber torque motor
Send these with your enquiry and an engineer can confirm the right cyber torque motor 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
WITTENSTEIN alpha cyber torque motor: frequently asked questions
What is the WITTENSTEIN alpha cyber torque motor?
Direct-drive torque motors for gearless rotary axes, built in a wide span of diameters. Published series figures include outer diameter 50 mm, outer diameter 540 mm, peak torque 1,700 Nm. It is made by WITTENSTEIN SE; Specify Motion can help source it or propose an equivalent.
Who makes the WITTENSTEIN alpha cyber torque motor?
The WITTENSTEIN alpha cyber torque motor is made by WITTENSTEIN alpha (WITTENSTEIN SE) and is listed here for engineers comparing options. Specify Motion is not affiliated with WITTENSTEIN SE; brand names are used only to identify the product.
What is the outer diameter of the WITTENSTEIN alpha cyber torque motor?
The published series minimum outer diameter is 50 mm. Individual models and sizes in the cyber torque motor 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 WITTENSTEIN alpha cyber torque motor?
Yes. On published figures, TI Series In-Runner Frameless Direct Drive Torque Motors is 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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