| 54KG·CM STALL | 0.108S/60° NO-LOAD | 8.4V RATED |
| 81G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The S8050D is the top of this 8.4 V coreless series: 54 kg·cm at 0.108 s/60°, 81 g, PWM input, in a 20 × 40 × 41 mm case. The 41 mm is the number to check before ordering — it is 2.6 mm taller than the S8035D and S8045D, and that comes from the case, not the mounting tabs.
It is a big-surface servo. 54 kg·cm at this speed carries a large flap or a heavy steering linkage without moving into a different voltage class, and the stainless geartrain is what the rating rests on: at 54 kg·cm a sintered or plastic first stage would be the service interval, not the motor.
Performance at each supply voltage
| Supply | No-load speed | Peak stall torque | Idle current | Stall current |
|---|---|---|---|---|
| 6.0 V | 0.158 s/60° (380 °/s) | 41 kg·cm (4.02 N·m / 569 oz·in) | 350 mA | 4.4 A |
| 7.4 V | 0.132 s/60° (455 °/s) | 47 kg·cm (4.61 N·m / 653 oz·in) | 390 mA | 5.4 A |
| 8.4 V | 0.108 s/60° (556 °/s) | 54 kg·cm (5.30 N·m / 750 oz·in) | 450 mA | 6.2 A |
Control specification
| Item | Specification |
|---|---|
| Command signal | PWM (50–333 Hz) |
| Amplifier | Digital controller |
| Pulse width range | 800–2200 µs |
| Neutral position | 1500 µs |
| Dead band | 1 µs |
| Rotating direction | CCW (1000–2000 µs) |
| Travel | 360°, customizable |
Mechanical specification
| Item | Specification | Item | Specification |
|---|---|---|---|
| Dimensions | 20 × 40 × 41 mm | Case material | CNC aluminium |
| Weight | 81 g | Geartrain | Stainless steel |
| Bearings | 2 × ball bearing | Motor | Coreless |
| Output spline | 25T / 5.94 mm | Horn in box | POM plastic |
| Lead | 300 mm | Travel limit | 360°, customizable |
| Operating temperature | −15 °C to 65 °C | Storage temperature | −20 °C to 70 °C |
| Ingress protection | Splash resistant (customizable) |
What’s in the box
- 1 × XQ-S8050D servo
- 1 × POM horn set
- 1 × mounting screw pack
Optional: metal horn, sold separately.
How to size it
Torque budget = load at the horn × horn length from spline centre × 1.5 safety factor.
Worked example: a 7 kg surface with its centre of pressure 40 mm from the spline centre needs 7 × 9.81 × 0.040 × 1.5 ≈ 4.12 N·m. The S8050D delivers 5.30 N·m at 8.4 V, about 29% headroom. At this size the horn dominates the calculation: 40 mm down to 32 mm removes about 0.8 N·m of requirement, which is more than the gap between this model and the one below it.
FAQ
Will it fit where an S8045D fits?
Check clearance first. Mounting holes and the 25T spline are identical, but the case is 2.6 mm taller (41 mm against 38.4 mm). The footprint fits; the space above the servo may not.
The photo says 54KG but the datasheet header says 52kg-cm — which is right?
54 kg·cm at 8.4 V is the measured peak stall in the inspection table, and the product photo carries the same number. The header string predates the top-rail measurement.
Why are there three torque figures?
Torque, speed and current scale with supply voltage: 41 kg·cm at 6.0 V, 47 at 7.4 V, 54 at 8.4 V. All three are published so you can size against the rail your BEC holds under load.
Can I run it directly from a 2S LiPo?
Yes. 8.4 V at full charge is the top rail in the sheet and the rail the 54 kg·cm figure is measured at. Stall current at that rail is 6.2 A — size the BEC and the wiring for it, not for the 450 mA idle figure.
Does it rotate continuously?
Travel is 360° when commanded over 1000–2000 µs, as a factory customization. Standard units work across the 800–2200 µs window.
Is there a serial version?
Yes — the XQ-S8050TTL is the same servo with a TTL serial command layer.
How much is 54 kg·cm in oz·in?
About 750 oz·in, or 5.30 N·m.
Downloads
- XQ-S8050D inspection specification (PDF, 847 KB)
Torque, speed and current at 6.0 / 7.4 / 8.4 V, mechanical data, control specification, mounting dimensions. - 2D dimension drawing (image)
Quick view of mounting hole positions and case depth; the same drawing is inside the datasheet.
