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Technical Specifications
Last Updated: 2026-10-23
Weight
Dimensions
Torque
Speed
Current
Temp
Wire
| Identity | |
| Brand |  |
| Product Number | HD-B4S |
| Category | Hobby |
| Performance | |
| Torque |
8.4V
444.48 oz-in
32.01 kg-cm
3.1 N-m
7.4V
347.25 oz-in
25.00 kg-cm
2.5 N-m
6.0V
291.69 oz-in
21.00 kg-cm
2.1 N-m
Above Average
|
| Speed |
8.4V
0.07 sec/60°
923.1 deg/s
153.8 RPM
7.4V
0.08 sec/60°
800.0 deg/s
133.3 RPM
6.0V
0.09 sec/60°
705.9 deg/s
117.6 RPM
Above Average
|
| Physical | |
| Weight | 2.36 oz67.0 gAverage |
| Dimensions |
L 1.61 in W 0.81 in H 1.51 in L 40.9 mm W 20.6 mm H 38.4 mm |
| Case Material | Aluminum |
| Drivetrain | |
| Motor Type | Brushless |
| Gears | Titanium / Steel |
| Gear Spline/Teeth | 25 T estimate |
| Rotation Mode | Positional |
| Rotation/Support | Dual Bearings |
| Control & Signal | |
| Modulation | Digital |
| Rotational Range | 120° |
| Pulse Cycle | 3.003 ms |
| Neutral Position | 1520 µs |
| Refresh Rate | 333 Hz |
| Electrical & Environment | |
| Operating Voltage | 6–8.4 V |
| Temperature | -20–60 °C-4–140 °F |
| Connectivity | |
| Connector | JR (Universal) estimate |
| Origin | |
| Country of Origin | Hong Kong |
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
| Torque | Above Average Stronger than 66% of 1055 Digital Standard servos at 6.0V |
| Speed | Above Average Faster than 86% of 1038 Digital Standard servos at 6.0V |
| Weight | Average Lighter than 40% of 1872 Digital Standard servos |
Performance Analysis
| Shaft Power | 6.35–12.64 W |
| Power Density | 6.421 W/in³ More power-dense than 87% of 1762 Digital Standard servos |
| Torque Density | 4.3536 oz-in/g Stronger than 68% of 1048 Digital Standard servos |
| Torque-to-Volume Ratio | 148.13 oz-in/in³ Denser torque than 64% of 1053 Digital Standard servos |
| Speed-to-Weight | 0.17559 (1/sec·g) Faster than 83% of 1031 Digital Standard servos |
| Speed-Torque Trade-off | 24.79 Better balanced than 43% of 1029 Digital Standard servos |
| Torque Gain per Volt | 21.83%/V More voltage-responsive (torque) than 88% of 868 Digital Standard servos |
| Speed Gain per Volt | 12.82%/V More voltage-responsive (speed) than 34% of 868 Digital Standard servos |
| Voltage Range Width | 2.4 V Wider voltage range than 54% of 1552 Digital Standard servos |
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