| 35KG·CM STALL | 0.100S/60° NO-LOAD | 8.4V RATED |
| 77G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The BLS8135D is the 35 kg·cm brushless servo in the standard 20 × 40 × 38.4 mm case, 77 g. At 8.4 V it swings 0.10 s/60°; drop to a 6.0 V receiver pack and the same servo is 20 kg·cm at 0.14 s.
Stainless steel geartrain on two ball bearings, CNC aluminium case with the fins milled into the sides, 25T-φ5.94 mm output and a POM horn. The mechanical limit is 210°, the dead band 1 µs, and the lead is 300 mm of three-wire cable.
This page covers the TTL build: the same mechanics, commanded over a serial bus so several servos can share one signal line and be addressed individually. Useful when the actuator count outgrows the PWM channels available.
Performance at each supply voltage
| Supply | No-load speed | Peak stall torque | Idle current | Stall current |
|---|---|---|---|---|
| 6.0 V | 0.140 s/60° (429 °/s) | 20 kg·cm (1.96 N·m / 278 oz·in) | 320 mA | 2.8 A |
| 7.4 V | 0.120 s/60° (500 °/s) | 28 kg·cm (2.75 N·m / 389 oz·in) | 370 mA | 3.5 A |
| 8.4 V | 0.100 s/60° (600 °/s) | 35 kg·cm (3.43 N·m / 486 oz·in) | 440 mA | 4.0 A |
Control specification
| Item | Specification |
|---|---|
| Command signal | TTL serial |
| Amplifier | Digital controller |
| Dead band | 1 µs |
| Rotating direction | CCW (1000–2000 µs) |
| Travel | 360°, customizable |
Mechanical specification
| Item | Specification | Item | Specification |
|---|---|---|---|
| Dimensions | 20 × 40 × 38.4 mm | Case material | Aluminium, CNC |
| Weight | 77 g | Geartrain | Stainless steel |
| Bearings | 2 × ball bearing | Motor | Brushless |
| Output spline | 25T-φ5.94 mm | Horn | Plastic, POM |
| Lead / connector | 300 mm, 3-wire | Mechanical limit | 210° |
| Operating temperature | −15 °C to 65 °C | Storage temperature | −20 °C to 70 °C |
| Ingress protection | Splash resistant (customizable) | Travel | 360°, customizable |
What’s in the box
- 1 × XQ-BLS8135TTL servo
- 1 × POM horn set
- 1 × mounting screw pack
Optional: metal horn, sold separately.
How to size it
Torque tracks the rail: 20 kg·cm at 6.0 V, 28 at 7.4 V, 35 at 8.4 V, at 0.14, 0.12 and 0.10 s/60°. On a 2S pack that sits near 7.4 V under load, plan on 28 kg·cm and treat 35 as the fresh-pack number.
Stall current is 4.0 A. Four of these on one BEC is 16 A at stall — size the BEC for the worst case, or run a separate servo rail. Brownouts on 35 kg·cm class models are almost always a supply problem, not a servo fault.
FAQ
BLS8135D or BLS8145D?
Same case, same 25T spline, same 20 × 40 × 38.4 mm footprint. The 8145D is 73 g and reaches 48 kg·cm at 8.4 V but draws 5.2 A at stall; the 8135D is 77 g, 35 kg·cm and 4.0 A. Pick on torque headroom versus current budget.
What supply voltage?
6.0 to 8.4 V. The headline 35 kg·cm is the 8.4 V figure; at 7.4 V it is 28 kg·cm and at 6.0 V it is 20.
Is the pulse width table valid for this unit?
No. The microsecond window printed on the inspection sheet belongs to the PWM build of the same servo. This unit is commanded over the serial bus — ask for the command set and register map before writing firmware.
How many can share one bus?
The limit is the address space and the current budget of the shared supply, not the signal pair. Keep the bus ground common with the power ground at a single point.
Other interfaces
Downloads
- XQ-BLS8135TTL inspection specification (PDF, 723 KB)
Torque, speed and current at each supply voltage, mechanical data, control specification, mounting dimensions. - 2D dimension drawing (image)
Mounting hole positions, case depth and overall height; the same drawing is inside the datasheet.
