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Technical Specifications
Last Updated: 2026-10-09| Identity | |
| Brand |  |
| Product Number | BMS-631 |
| Category | Hobby |
| Discontinued | Yes |
| Performance | |
| Torque |
6.0V
86.00 oz-in
6.19 kg-cm
0.6 N-m
4.8V
69.00 oz-in
4.97 kg-cm
0.5 N-m
|
| Speed |
6.0V
0.08 sec/60°
750.0 deg/s
125.0 RPM
4.8V
0.10 sec/60°
600.0 deg/s
100.0 RPM
|
| Physical | |
| Weight | 1.52 oz43.0 gAbove Average |
| Dimensions |
L 1.594 in W 0.787 in H 1.516 in L 40.5 mm W 20.0 mm H 38.5 mm |
| Drivetrain | |
| Gears | Plastic |
| Gear Spline/Teeth | 25 T estimate |
| Rotation/Support | Dual Bearings |
| Control & Signal | |
| Modulation | Analog |
| Pulse Cycle | 8 ms |
| Neutral Position | 1520 µs |
| Refresh Rate | 125 Hz |
| Control System | PWM |
| Electrical & Environment | |
| Operating Voltage | 4.5–6.5 V |
| Power Source | Ni-MH / Ni-CD |
| Connectivity | |
| Connector | JR (Universal) |
Disclaimer: Most data is sourced from the manufacturer. Some data is sourced from our loyal community and with the help of AI. We aim for accuracy but are not responsible for inaccurate information.
Class Comparison
| Weight | Above Average Lighter than 73% of 448 Analog Standard servos |
Performance Analysis
| Shaft Power | 1.28–1.99 W |
| Power Density | 1.045 W/in³ More power-dense than 81% of 437 Analog Standard servos |
| Torque Density | 1.6047 oz-in/g |
| Torque-to-Volume Ratio | 36.28 oz-in/in³ |
| Speed-to-Weight | 0.23256 (1/sec·g) |
| Speed-Torque Trade-off | 6.90 |
| Voltage Range Width | 2.0 V Wider voltage range than 90% of 229 Analog Standard servos |
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Reviews (2)
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Hugo Biermann
July 16, 2017Application(s): Tamiya Lunchbox and DT01
Comments: Its a budget servo that performs like a beast.
Replaced an aging servo in my dt01 with one of these and was super impressed.
Its that impressive that I got another one for my lunchbox. Replacing a Savox 0251mg. Its been taking a huge beating and not one glitch. Super fast and accurate.Can highly recommend. Will buy more for future projects.
DustBen
January 20, 2012Application(s): I use the servos in 60 size (5-7 pound, 600-850 sq inch) sport and aerobatic models.
Comments: They mount where the previously held Hitec HS425BB was without modification.
The street price is $12.95 at a popular internet supply site.I feel entirely confident using these after 3-4 hours of bench and flight time.
I give this a 5 star rating not because of pure quality (they're very good), but because the performance for the cost is superb (value).