DC servo motor
FAULHABER BXT
Flat outer-rotor brushless motors with a high torque-to-length ratio, offered with or without housing.
Key specifications
| Outer diameter | 22–42 mm |
|---|---|
| Rated torque (max) | 0.134 Nm |
| Speed (max) | 10,000 rpm |
| Power (max) | 100 W |
| Voltage | 6-48 V |
Summarised in our own words from Dr. Fritz Faulhaber GmbH & Co. KG's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1
Notes on this data
Faulhaber lists 'torque up to' per series without saying whether it is continuous or peak; stored as torque_Nm_rated_max (converted from mNm). 4221 BXT R (unhoused) 134 mNm / 100 W. Page length figures inconsistent for 4221 BXT H (21 vs 22 mm).
Specify Motion is not affiliated with Dr. Fritz Faulhaber GmbH & Co. KG. FAULHABER and BXT 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 FAULHABER 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.
A single 110 mm, 1.2 kW, 48 VDC servo motor giving 4 Nm at 3000 rpm for higher-power low-voltage systems, paired with Kinco FD1 and OD drives.
| Published maximum | BXT | SMH Series Low-Voltage DC Servo Motor … |
|---|---|---|
| Rated torque | 0.13 Nm | 4 Nm meets or exceeds |
| Speed | 10,000 rpm | — |
| Power | 100 W | 1,200 W meets or exceeds |
Leadshine low-voltage PMSM servo motors from a 25 mm 33 W unit up to a 130 mm 2 kW unit, wound for 24-60 V DC buses. Fully published data covers torque to 6.4 Nm rated / 16 Nm peak, 17-bit absolute or 2500 ppr incremental encoders and IP65. Designed for ELD2, 2ELD2 and ELD3 drives.
| Published maximum | BXT | ELVM Series Low-Voltage DC Servo Motors |
|---|---|---|
| Rated torque | 0.13 Nm | 6.4 Nm meets or exceeds |
| Peak torque | — | 16 Nm |
| Speed | 10,000 rpm | 6,000 rpm |
| Power | 100 W | 2,000 W meets or exceeds |
Low-voltage brushless DC servo motors for 48 or 96 VDC systems, with a 12-slot/10-pole design, matched to the Kinco FD1X5 drive and aimed at robotics, CNC and automated lines.
| Published maximum | BXT | SMK Series Low-Voltage DC Servo Motors |
|---|---|---|
| Rated torque | 0.13 Nm | — |
| Speed | 10,000 rpm | — |
| Power | 100 W | 5,000 W 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.
Other dc servo motor series
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Tell us how you use the FAULHABER BXT: the load, speed, duty and environment. Our engineers will confirm whether it is still the right part, find it for you, or propose an alternative that fits better.
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