The KST X20-8.4-50 V8.0 Brushless Metal Gear Digital Servo is a high-torque standard servo for large-scale RC planes, 1:8 and 1:10 on-road/off-road RC cars, crawlers, and other demanding control systems. KST lists it as a 45Kgf.cm class servo at 8.4V.
Verified KST data lists a DC 6.0V-8.4V voltage range, up to 45Kgf.cm torque at 8.4V, and 0.15sec/60deg speed at 8.4V. It uses a coreless DC motor, hardened steel gears, potentiometer feedback, an aluminum alloy case, and 2 ball bearings.
With a 40.5 x 21 x 42mm case and about 78g weight, X20-8.4-50 V8.0 is suited for users who need strong torque rather than ultra-fast track-servo speed.
Product Images
Features
- 45Kgf.cm peak torque - Listed torque reaches 45Kgf.cm at 8.4V.
- 0.15sec HV response - Listed speed reaches 0.15sec/60deg at 8.4V.
- Coreless DC motor - Supports smooth high-torque control.
- HV operating range - Supports DC 6.0V-8.4V.
- Hardened steel gears - Adds durability for high-load linkages.
- Aluminum alloy case - Provides a strong metal housing for heat dissipation.
- 25T 6mm output spline - Uses the listed standard servo spline.
- 2BB construction - Uses dual ball bearings for output support.
- Programmable soft start - KST lists soft start and programmability.
- 100deg default travel - Default travel is listed as +/-50deg.
Specifications
| Parameter | Value |
|---|---|
| Model | KST X20-8.4-50 V8.0 |
| Shopify SKU | KST-X20-84-50 |
| Rated Voltage | DC 7.4V |
| Voltage Range | DC 6.0V-8.4V |
| Torque | 38Kgf.cm @ 6.0V; 42Kgf.cm @ 7.4V; 45Kgf.cm @ 8.4V |
| Speed | 0.20sec/60deg @ 6.0V; 0.17sec/60deg @ 7.4V; 0.15sec/60deg @ 8.4V |
| Working Frequency | 1520us / 333Hz |
| Default Travel Angle | +/-50deg = 100deg total |
| Command Interface | PWM command; pulse length 900us-2100us |
| Output Shaft Spline | 25T, 6mm |
| Case Material | Aluminum alloy |
| Motor Type | Coreless DC motor |
| Gear Set Material | Hardened steel |
| Position Sensor | Potentiometer |
| Ball Bearing | 2BB |
| Case Dimensions | 40.5 x 21 x 42mm +/-0.2mm |
| Weight | 78g +/-10% |
| Temperature Range | -10C to +65C |
| Soft Start | Programmable |
| Programmable | Yes |
Reference Documents
Application
- Large RC aircraft - Suitable where a standard-size HV servo and high torque match the airframe requirements.
- RC cars and crawlers - Can be used in compatible steering systems after checking size, spline, and voltage.
- Aerobatic airplanes and jets - Works for demanding control surfaces when torque and speed match the design.
- Scale model control - Useful for high-load PWM servo actuation in compatible scale models.
- Servo upgrade projects - Can replace compatible standard servos after checking case size, output spline, and travel.
- PWM-controlled mechanisms - Supports custom mechanisms using the listed PWM command range.
Packing List
| Description | Quantity |
|---|---|
| KST X20-8.4-50 brushless standard servo | 1 |
| Accessory pack | 1 |
FAQ
X20-8.4-50 lists 45Kgf.cm at 8.4V and 0.15sec/60deg speed. X20-4208 is faster at 0.07sec/60deg and lists 46Kgf.cm at 8.4V, with contactless sensing and 6BB construction.
No. The current Shopify product is a single variant with SKU KST-X20-84-50.
The technical specification lists 45Kgf.cm at 8.4V.
The fastest listed speed is 0.15sec/60deg at 8.4V.
The listed voltage range is DC 6.0V-8.4V.
The package listing confirms one X20-8.4-50 brushless standard servo and one accessory pack.
The technical specification lists a 25T, 6mm output shaft spline.
Confirm the 40.5 x 21 x 42mm case, 25T 6mm spline, HV power setup, and required torque-speed balance.