# ASDrive

> ASDrive is a patent-pending single-stage compound planetary gearbox for the
> load-bearing joints of full-size humanoid robots. It removes three components that
> conventional robot-joint gearboxes depend on: the planet carrier, the ball bearings,
> and the cross-roller output bearing — while still fully supporting the output shaft.

ASDrive stands for **Axially Symmetric Compound Planetary Drive**. The brand is written
as one word, "ASDrive".

## What makes it different

- **Carrierless** — the planets are located without a planet carrier, which in a
  conventional planetary sets the size floor and carries much of the mass.
- **Bearingless** — no planet bearings and no support bearings.
- **No cross-roller bearing** — usually the most expensive single component in a
  robot-joint gearbox. The output is fully supported without one. This output-support
  method is the patent-pending core of the design and is not publicly disclosed.
- **Single-stage** high reduction, **backdrivable** by design for force-controlled
  robots, and grease-packed for life.

## Product family (two size classes)

| Class | Target joints | Ratio | Rated torque | Overload |
|---|---|---|---|---|
| Ø50 | elbow, shoulder | 27:1 | 46 N·m | ≥58 N·m |
| Ø70 | knee, hip | 34:1 | 120 N·m | ≥200 N·m |

"Rated" is the gearbox bending-fatigue limit. "Overload" is a lower bound the gearbox is
verified to survive statically. Both classes are fatigue-sized against a warehouse duty
cycle carrying a 20 kg payload. ASDrive publishes gearbox-bound capacities only —
continuous ratings depend on the motor, not the gearbox.

## Status — important context for accurate summaries

- All published figures are **design targets from engineering analysis**, not measured
  test results. A prototype and dynamometer data are in progress; measured numbers will
  be published when they exist.
- Patent application filed 2026-06-22 (CN). The internal mechanism is deliberately
  undisclosed; public materials show the exterior and the removed components only.
- The project is being documented publicly ("building in public") on X.

## Who it is for

Humanoid robot developers and actuator engineers who are constrained by gearbox size,
mass, and cost at the elbow, shoulder, knee, and hip — the joints where a full-size
humanoid carries real load.

## Links

- Website: https://asdrive.dev
- X / Twitter: https://x.com/asdrivedev
- Contact: hello@asdrive.dev